ANTR W5 Qs

A: Gluteus maximus. The sacrotuberous liga- ment runs from the lower lateral sacrum and the coccyx to the ischial tuberosity. It is important in stabilizing the sacroiliac joint and, together with the sacrospinous ligament, defines the lesser sciatic foramen. Furthermore, it provides the gluteus maximus muscle additional firm surface area for origin of its fibers. It is important to notice that skeletal muscle fibers do not always attach only to bone. They may utilize any available structure to increase the surface area for attachment of fibers. Since muscle force production is directly proportional to the physiological cross-sectional area of a muscle, increasing the space available for packing in muscle fibers is an important mechanical aspect of muscle anatomy. Choice B (Gluteus medius) is incorrect. This muscle attaches only to bone, the superior aspect of the greater trochanter. This muscle is not located close to the sacrotuberous ligament. Choice C (Gluteus minimus) is incorrect. The gluteus minimus, like the gluteus medius, attaches to the superior aspect of the greater trochanter. This muscle is not located in proximity to the sac- rotuberous ligament. Choice D (Gemelli) is incorrect. The small gemellus superior and inferior muscles originate from bony locales (ischial spine and ischial tuberosity, respectively) and attach onto the tendon of the obturator internus muscle in order to exert their actions against the greater trochanter of the femur. They pass deep to the sacrotuberous ligament, but do not attach onto it. Choice E (Obturator externus) is incorrect. Both the obturator externus and internus muscles take most of their origins from the surfaces of the obturator membrane. Thus, both muscles are additional examples of muscles that use ligaments to increase the surface area available for muscle fiber attachment.

A 15-year-old girl is struck by a car while crossing the street. She suffers numerous pelvic injuries, including tearing of the sacrotuberous ligament. The damage to this ligament will most likely cause direct trauma to which of the following muscles? (A) Gluteusmaximus (B) Gluteus medius (C) Gluteusminimus (D) Gemelli (E) Obturator externus

E: Phalanges. Accutane (retinoic acid; vitamin A) is a useful therapeutic drug in relieving skin dis- orders such as acne. However, it also is a recognized terato- genic agent that should not be utilized during pregnancy. Both upper and lower limbs follow the same pattern of develop- ment, except that corresponding events occur slightly later (by ~2 days) in the lower limb. One aspect of this pattern is that development proceeds along the proximo-distal axis of the limb, with the more proximal skeletal elements differentiating first, followed by the more distal structures. Overall, the major formative events take place from late week 4 to week 8. In this case, the Accutane was used during the later stages of limb development. The structures most likely affected are the most distal elements, the phalanges. Choice A (Ilium) is incorrect. Because of the timing of the mother's use of Accutane, the more distal skeletal components, which are the last to differentiate, are most likely affected. The ilium, a bony component of the coxal or hip bone, would not be affected. Choice B (Femur) is incorrect. Because of the timing of the mother's use of Accu- tane, the more distal skeletal components, which are the last to differentiate, are most likely affected. The femur would not be affected. Choice C (Patella) is incorrect. Because of the timing of the mother's use of Accutane, the more distal skel- etal components, which are the last to differentiate, are most likely affected. The patella, a sesamoid bone in the quadriceps tendon, would not be affected. Choice D (Tibia) is incorrect. Because of the timing of the mother's use of Accutane, the more distal skeletal components, which are the last to differentiate, are most likely affected. The tibia, a long bone in the leg, would not be affected.

A 15-year-old girl, unaware that she is pregnant, borrows her friend's Accutane (retinoic acid; vitamin A) to combat an acne problem. She uses the Accutane for about 2 months, which corresponds to weeks 7 to 15 of the embryonic development of her fetus. Which of the following skeletal elements is most likely to be absent in the newborn infant? (A) Ilium (B) Femur (C) Patella (D) Tibia (E) Phalanges

A: Medial plantar nerve. The medial plantar nerve, which is homologous to the median nerve in the hand, innervates four intrinsic foot muscles: first Lumbrical, Abduc- tor hallucis, Flexor digitorum brevis, and Flexor hallucis brevis (mnemonic = "LAFF" muscles). This nerve supplies cutaneous innervation to the medial three and a half toes on the plantar surface of the foot. The given photo shows the sensory distri- bution of the medial plantar nerve, but please remember that the other cutaneous nerves of the plantar aspect of the foot (lateral plantar nerve on the lateral aspect, tibial nerve proxi- mally, and saphenous nerve medially) will have some overlap with this distribution pattern. Due to the depth of the cut, the medial plantar nerve, which travels between the first and second layers of the plantar foot musculature, was most likely severed, resulting in loss of cutaneous sensation to the plantar surface of the medial three toes and loss of motor innerva- tion to the abductor hallucis and flexor hallucis brevis. The tendon of the flexor hallucis longus muscle, which resides in the second layer of plantar foot musculature, would have also been severed by this cut. Despite being innervated by the tibial nerve, the tendon of this muscle would have been severed due to the depth of the cut, resulting in the complete inability to flex the big toe, seen in this patient. Choice B (Lateral plantar nerve) is incorrect. The lateral plantar nerve, which is homol- ogous to the ulnar nerve in the hand, innervates all of the intrinsic foot muscles, with the exception of the four muscles supplied by the medial plantar nerve. This nerve also provides cutaneous (sensory) innervation to the lateral one and a half toes. Due to the location of the laceration near the first (or medial) cuneiform bone and the symptoms of this patient, this nerve was not severed in this injury. Choice C (Sural nerve) is incorrect. The sural nerve is a cutaneous nerve, so the motor deficits seen in this patient (weakness in flexing and abducting the big toe) would not be possible. The course of this nerve parallels the small saphenous vein, and damage to the sural nerve would lead to numbness and paresthesia in the dor- sal aspect of the lateral fifth toe and lateral malleolus of the fibula. Choice D (Deep fibular nerve) is incorrect. The deep fibular (peroneal) nerve supplies motor innervation to the four muscles of the anterior compartment of the leg and two intrin- sic muscles of the foot: extensor digitorum brevis and extensor hallucis brevis. Its cutaneous territory lies between the first and the second toes on the dorsal surface of the foot. So, the deep fibular nerve is not involved in this patient. Choice E (Superficial fibular nerve) is incorrect. The superficial fibular nerve supplies motor innervation to the two muscles (fibu- laris longus and brevis) of the lateral compartment of the leg and cutaneous (sensory) innervation to the distal third of the anterior surface of the leg and dorsum of the foot. Because the patient did not present with weakness during eversion of the foot at the ankle joint or numbness on the dorsum of the foot, this nerve was not damaged in this patient.

A 16-year-old boy was fishing barefoot in a muddy river when the plantar surface of his foot was cut by unseen debris. He suffers a large transverse cut, penetrating the first two layers of his plantar musculature, in the area of the first cuneiform bone. In the emergency room, his physician notes a complete inability to flex and abduct the big toe and numbness on the plantar aspect of the three medial toes. Which of the following nerves is most likely damaged? (A) Medial plantar nerve (B) Lateral plantar nerve (C) Sural nerve (D) Deepfibularnerve (E) Superficial fibular nerve

D. In this patient the pain is produced with moderate contraction of the quadriceps femoris muscle; this muscle extends the knee

A 16-year-old male presents to the office because he is experiencing general pain around his knee following his practices for the high school track team. Physical exam reveals extreme pain when he attempts to extend his knee against resistance. The most likely explanation for this pain is injury to the distal attachment of which of the following muscles? A. Adductor magnus B. Semimembranosus C. Gastrocnemius D. Quadriceps femoris E. Biceps femoris

A. The popliteal lymph nodes are the first to re- ceive lymph from the foot. These nodes will then drain into the deep inguinal nodes and then to the external iliac nodes. The superficial inguinal and internal iliac nodes do not receive lymph from the foot.

A 16-year-old male received a superficial cut on the lateral side of his foot while playing football and is admitted to the emergency department where the wound is sutured. Four days later the patient returns to the hospital with high fever and swollen lymph nodes. Which group of nodes will first receive lymph from the infected wound? A. Popliteal B. Vertical group of superficial inguinal C. Deep inguinal D. Horizontal group of superficial inguinal E. Internal iliac

A. The medial meniscus is firmly attached to the medial (tibial) collateral ligament. Damage to the me- dial collateral ligament often causes concomitant damage to the medial meniscus because of this rela- tionship. The anterior cruciate ligament lies inside the knee joint capsule but outside the synovial cavity. It is taut during extension of the knee and may be torn when the knee is hyperextended. If this were dam- aged along with the medial meniscus and medial cruciate ligament, an "unhappy triad" (of O'Donahue) injury would result. The lateral meniscus is not at- tached to the medial collateral ligament but receives muscular attachment to the popliteus muscle. The posterior cruciate ligament also lies outside of the synovial cavity and limits hyperflexion of the knee. The tendon of the semitendinosus forms one third of the pes anserinus, with the tendons of the sartorius and gracilis making up the other two thirds. The pes anserinus (goose foot) is located at the medial border of the tibial tuberosity, and a portion can be used for surgical repair of the anterior cruciate ligament.

A 19-year-old football player was hit on the lateral side of his knee just as he put that foot on the ground. Unable to walk without assistance, he is taken to the hospital. An MRI examination reveals a torn medial col- lateral ligament. Which structure would most likely also be injured due to its attachment to this ligament? A. Medial meniscus B. Anterior cruciate ligament C. Lateral meniscus D. Posterior cruciate ligament E. Tendon of the semitendinosus

E. Tearing of the plantar calcaneonavicular (spring) ligament The plantar calcaneonavicular (spring) ligament supports the head of the talus in maintaining the medial longitudinal arch of the foot. It is dynamically supported in this task by the tendon of the posterior tibialis muscle.

A 19-year-old patient is admitted to the orthopaedic service with a complaint of severe pain in his very swollen and discolored foot. He states that he hurt the foot when jumping from his girlfriend's bedroom window to the concrete driveway below. Plain radiographs reveal that the head of the talus has become displaced inferiorly, causing the medial longitudinal arch of the foot to fall. What would be the most likely, serious problem in such a case? A. Disruption of the distal tibiofibular ligament B. Rupture of the anterior tibialis tendon C. Interruption of the plantar aponeurosis D. Sprain of the anterior talofibular ligament E. Tearing of the plantar calcaneonavicular (spring) ligament

A. With sufficient downward force, the head of the talus can break through the plantar calcaneona- vicular (spring) ligament, causing the medial longitu- dinal arch of the foot to fall, forcing the anterior part of the foot into abduction. The plantar calcaneona- vicular ligament is attached between the sustentacu- lum tali of the calcaneus and the medial surface of the navicular bone, with the head of the talus lying di- rectly upon the inner surface of the ligament. The cuboid bone is located lateral and anterior to the talus bone and would not be fractured. The plantar apo- neurosis, a dense, wide band of tissue beneath the fascia of the sole, attaches to the calcaneus and ends distally in longitudinal bands to each of the toes. It stretches very little, even under very heavy loads, and would not break in this case. The anterior talofibular ligament is very often injured in "sprained ankle" but would not be directly involved here. The distal tibio- fibular joint is a fibrous (and usually nonsynovial) type of joint between the tibia and fibula, not in- volved in the displacement of the talus bone. GAS 518, 519, 614; GA 311

A 19-year-old patient is admitted to the orthope- dic service with a complaint of severe pain in his very swollen and discolored foot. He states that he hurt the foot when jumping from his girlfriend's bedroom window to the concrete driveway below. Plain film radiographic studies reveal that the head of the talus has become displaced inferiorly, thereby causing the medial longitudinal arch of the foot to fall. What would be the most likely, serious problem in such a case? A. Tearing of the plantar calcaneonavicular (spring) ligament B. Fracture of the cuboid bone C. Interruption of the plantar aponeurosis D. Sprain of the anterior talofibular ligament E. Disruption of the distal tibiofibular ligament

B: Anterior talofibular ligament. The ankle is the most frequently injured major joint in the body. Torn ligaments (ankle sprains) are commonly seen following inver- sion injuries, where the joint is twisted on a weight-bearing plantar flexed foot (as described in this patient). The most commonly sprained ankle ligament is the anterior talofibu- lar ligament on the lateral side of the ankle, and this injury results in instability of the joint. If this ankle injury were more severe, additional ligaments of the lateral side of the ankle would also be involved, specifically the calcaneofibular and posterior talofibular ligaments. Choice A (Calcaneofibular ligament) is incorrect. The calcaneofibular ligament is often injured in severe ankle sprains following forced inversion of the foot but only after the anterior talofibular ligament would have incurred damage. However, in this athlete, the ankle sprain was not severe and she was able to continue playing. Therefore, the calcaneofibular ligament was most likely not involved. Choice C (Posterior talofibular ligament) is incor- rect. The posterior talofibular ligament would only be dam- aged in the most severe cases of forced inversion of the ankle joint following injury to the anterior talofibular and calcaneo- fibular ligaments. Given the nature of this injury, the anterior talofibular ligament was the only ligament involved. Choice D (Plantar calcaneonavicular ligament) is incorrect. The plantar calcaneonavicular (spring) ligament connects the sustentacu- lum tali of the calcaneus with the plantar surface of the navic- ular bone. It supports the head of the talus and helps maintain the medial longitudinal arch of the foot. This ligament would not be involved with a sprained (or twisted) ankle. Choice E (Medial [deltoid] ligament) is incorrect. The medial (deltoid) ligament of the ankle reinforces the medial aspect of the ankle joint and would be injured during forced eversion injuries. This ligament is much stronger than the lateral ligaments of the ankle (calcaneofibular, anterior talofibular, posterior talo- fibular ligaments) and would not be involved in this inversion injury.

A 21-year-old female basketball player lands on her opponent's foot after jumping to rebound the basketball. Her foot is forcefully inverted, and when leaving the court, she tells her trainer that she twisted or sprained her ankle. After getting her ankle taped for support, she reenters the game. What ligament was most likely damaged? (A) Calcaneofibularligament (B) Anterior talofibular ligament (C) Posterior talofibular ligament (D) Plantar calcaneonavicular ligament (E) Medial (deltoid) ligament

B. The calcaneofibular ligament is a round cord that passes posteroinferiorly from the tip of the lateral malleolus to the lateral surface of the calcaneus. A forced inversion of the foot can result in tearing of the calcaneofibular ligament and sometimes the anterior talofibular ligament as well. Both of these ligaments act to stabilize the foot and prevent an inversion in- jury. The long plantar ligament passes from the planter surface of the calcaneus to the groove on the cuboid and is important in maintaining the longitudi- nal arch of the foot. The short plantar ligament is lo- cated deep (superior) to the long plantar ligament and extends from the calcaneus to the cuboid and is also involved in maintaining the longitudinal arch of the foot. The deltoid (medial ligament of the ankle) at- taches proximally to the medial malleolus and fans out to reinforce the joint capsule of the ankle. GAS 606; GA 316-317, 332

A 22-year-old football player is admitted to the hospital with pain and swelling over the lateral aspect of the ankle. The emergency department doctor diagnoses an inversion sprain. Which ligament was most likely injured? A. Calcaneonavicular (spring) B. Calcaneofibular C. Long plantar D. Short plantar E. Deltoid

C. Fractured medial malleolus Because the deltoid ligament is so strong, hypereversion injuries spare the deltoid ligament and avulse the medial malleolus. Fibular fractures also tend to accompany hypereversion injuries.

A 22-year-old male basketball player severely injured his ankle during training and is admitted to the emergency department. Upon physical examination the patient shows hypereversion of his ankle. Which of the following injuries is likely to have occurred in this individual? A. Torn anterior talofibular ligament B. Torn calcaneofibular ligament C. Fractured medial malleolus D. Torn plantar calcaneonavicular (spring) ligament

A. The common fibular (peroneal) nerve passes around the head of the fibula and gives off deep (L4-5) and superficial fibular (peroneal) nerve (L5, S1-2) branches. The two nerves supply the dorsiflexors and evertors of the foot, respectively. In this case, the tibi- alis anterior and extensor digitorum longus are the only muscles listed that are supplied by either of these nerve branches, and both are innervated by the deep fibular (peroneal) nerve. The fibularis (peroneus) bre- vis and longus are innervated by the superficial fibular (peroneal) nerve and are evertors of the foot. The tib- ial nerve supplies each of the other muscles listed.

A 22-year-old male martial arts competitor was examined by the clinician because of pain and serious disability suffered from a kick to the side of his knee. Physical examination revealed a dark bruise just distal to the head of the fibula. Which of the following mus- cles will most likely be paralyzed? A. Tibialis anterior and extensor digitorum longus B. Tibialis posterior C. Soleus and gastrocnemius D. Plantaris and popliteus E. Flexor digitorum longus and flexor hallucis longus

B. The tibial nerve divides into the medial and lateral plantar nerves on the medial side of the ankle. These two nerves provide sensation for the sole of the foot. Sensory supply to the dorsum of the foot is pro- vided mostly by the superficial fibular (peroneal) nerve, with the deep fibular (peroneal) nerve provid- ing sensation for the skin between the first and sec- ond toes. Foot drop would be caused by interruption of the common fibular (peroneal) nerve. Sensory loss to the lateral side of the foot results from loss of the sural nerve. Paralysis of the extensor digitorum brevis would be attributed to injury to the terminal motor branch of the deep fibular (peroneal) nerve.GAS 625-626; GA 341-342

A 22-year-old man is admitted to the emergency department after falling from his bicycle. Radiographic examination reveals a fracture of the tibia above the ankle. MRI and physical examination reveal that the tibial nerve is severed on the posterior aspect of the tibia. Which of the following signs will most likely be present during physical examination? A. Sensory loss of the dorsum of the foot B. Sensory loss on the sole of the foot C. Foot drop D. Paralysis of the extensor digitorum brevis E. Sensory loss of the entire foot

B: Tachycardia. Tachycardia (rapid beatings of the heart) would be seen in this patient. Acute blood loss induces the following hemodynamic changes: tachycardia, hypotension (subnormal arterial blood pressure), generalized arteriolar vasoconstriction, and generalized venoconstriction. Choice A (Increased pulse in right dorsalis pedis artery) is incorrect. Due to the hemodynamic changes associated with acute blood loss, the pulse in the right dorsalis artery would be diminished due to generalized arteriolar vasoconstric- tion, which greatly reduces peripheral blood flow to ensure that vital organs in the thorax are receiving blood. Choice C (Warm right foot) is incorrect. Due to the hemodynamic changes associated with acute blood loss, the right foot would feel cold due to generalized arteriolar vasoconstriction. Choice D (Increased hematocrit) is incorrect. Due to the hemodynamic changes associated with acute blood loss, the hematocrit (the proportion of blood volume that is occupied by red blood cells) would be decreased from the normal 46% value seen in men due to the loss of blood. Lowered hematocrit levels imply significant hemorrhage. Choice E (Hypertension) is incorrect. Due to the hemodynamic changes associated with acute blood loss, hypertension (high arterial blood pressure) would not be seen in this patient due to the severe blood loss. Due to his blood loss, the patient would be hypotensive.

A 22-year-old soldier is injured from shrapnel from an improvised explosive device in the right upper thigh, below the midpoint of the inguinal ligament. Though he received field dressings from a medic, he arrives at the military hospital hav- ing lost copious amounts of blood. What sign and/or symptom would accompany this patient's presentation? (A) Increased pulse in the right dorsalis pedis artery (B) Tachycardia (C) Warm right foot (D) Increased hematocrit (E) Hypertension

D. The gluteus maximus inserts into the gluteal tuberosity and the iliotibial tract. Although the gluteus maximus would continue to contract at the regions of insertion, their orientation would be displaced by the fracture. The gluteus medius, gluteus minimus, obtura- tor internus, and piriformis all insert on some aspect of the greater trochanter of the femur.

A 22-year-old woman is admitted to the emer- gency department after another vehicle collided with the passenger side of the convertible in which she was riding. Radiographic examination reveals an avulsion fracture of the greater trochanter. Which of the follow- ing muscles would continue to function normally if such an injury was incurred? A. Piriformis B. Obturator internus C. Gluteus medius D. Gluteus maximus E. Gluteus minimus

C. iliotibial band syndrome (ITBS). ITBS is one of the leading causes of lateral knee pain in runners, and it is often seen in runners who increase the intensity of their workouts too rapidly. The iliotibial band (tract) is a lateral thickening of the fascia lata that extends inferiorly to the ante- rolateral aspect of the lateral condyle of the tibia and stabilizes the knee during running. When the knee is flexed at approxi- mately 45 degrees, the iliotibial tract passes posterior to the lateral femoral epicondyle. In distance runners and cyclists, repeated flexion and extension of the knee cause friction on the lateral femoral epicondyle due to the iliotibial band rubbing against the bone. ITBS, and its associated pain and inflammation of the lateral knee, is exacerbated by downhill running and chronic repetitive foot strikes during long runs. Choice A (Sprained fibular [lateral] collateral ligament [FCL]) is incorrect. Lateral knee pain can generally be traced to three anatomical sites: ITBS (seen in this patient), a torn lateral meniscus, and a sprained FCL. The latter two scenarios usu- ally follow trauma to the knee joint, which was not reported in this patient and can be ruled out as a diagnosis. FCL sprains are usually due to a blow to the medial side of the knee, which sprains or tears the FCL; however, this type of trauma was not reported in this patient. Choice B (Patellofemoral pain syndrome) is incorrect. Patellofemoral pain syndrome is often seen in runners who increase the intensity of their workouts too rapidly. This syndrome results from imbalances in the forces controlling patellar tracking during knee flexion and extension, and patients present with anterior knee pain that is described as being around, underneath, or behind the patella. While this syndrome is similar in presentation to ITBS, it can be distinguished from ITBS due to the presence of anterior knee pain versus the lateral knee pain seen in this patient. Choice D (Torn lateral meniscus) is incorrect. Though a patient with a torn lateral meniscus would report lateral knee pain, this presentation is usually due to trauma, particularly when the flexed knee is twisted. Patients with torn menisci present with pain, inflammation, tenderness, popping or clicking of the joint, and knee joint instability. Though this patient had lateral knee pain with some of these signs and symptoms, there was no trauma reported, which would make a meniscus tear unlikely. Choice E (Pes anserinus bur- sitis) is incorrect. The pes anserinus (L: foot of a goose) is the combined tendon insertions of the Sartorius, Gracilis, and semiTendinosus muscles (mnemonics: 1. SGT, an abbre- viation for sergeant, and 2. "Say Grace Before Tea," which takes into account the presence of the anserine Bursa) at the medial border of the tuberosity of the tibia. Pes anserinus bursitis is often seen in athletic overuse; however, it would be responsible for medial knee pain, not the lateral knee pain seen in this patient.

A 23-year-old female medical student notices she was gaining weight due to a sedimentary lifestyle and compulsive study- ing. Therefore, she decides to run in a marathon and starts her training by running 6 miles each morning before class. After 2 weeks, she presents with right lateral knee pain and inflammation, specifically in the area of the lateral femoral epicondyle. This pain intensifies throughout her morning jogs, especially when her right foot strikes the ground or when she is running downhill. What is most likely diagnosis in this patient? (A) Sprained fibular (lateral) collateral ligament (FCL) (B) Patellofemoral pain syndrome (C) Iliotibial band syndrome (ITBS) (D) Torn lateral meniscus (E) Pes anserinus bursitis

B. The original axial vessel of the lower limb is retained as the (usually tiny) ischiatic branch of the inferior gluteal artery. In some cases this vessel is re- tained as the primary proximal vessel to the limb, wherein there is hypoplastic development of the femoral artery. Aneurysms of the enlarged ischiatic artery in the gluteal region are relatively common, as is rupture of the vessel (with profuse bleeding) if they are exposed in the gluteal area. The profunda femoris or deep femoral branch of the femoral artery usually provides three perforating branches to the posterior compartment, but not a branch such as that de- scribed. The descending branch of the medial circum- flex femoral anastomoses with the first perforator. The superior gluteal artery anastomoses with the in- ferior gluteal by a descending branch or branches. The descending branch of the lateral circumflex femo- ral is the descending genicular artery, which anasto- moses with the superior lateral genicular branch of the popliteal artery. GAS 473, 474-477, 533, 540, 541, 554; GA 182, 232, 282-283, 292, 294-295

A 23-year-old male is admitted to the emergency department with pain and cyanosis of his right lower limb. Doppler ultrasound studies reveal deficiency in development of his femoral artery, which appears to terminate midthigh. A thrombotic occlusion is seen in an unusual, rather tortuous, large vessel in the posterior compartment of the thigh, arising in the gluteal area and continuous inferiorly with a normal- appearing popliteal artery. It is decided that a vascu- lar graft should be placed from the femoral artery to the popliteal artery. What is the identity of the aber- rant artery? A. A large, fifth perforating branch of the femoral B. An ischiatic branch of the inferior gluteal artery C. Descending branch of the medial circumflex femoral D. Descending branch of the superior gluteal artery E. An enlarged descending lateral circumflex femoral artery

A. The ventral ramus of L4 contains both sensory and motor nerve fibers. Injury from a stab wound could result in loss of sensation from the dermatome supplied by this segment. A dermatome is an area of skin supplied by a single spinal nerve; L4 dermatome supplies the medial aspect of the leg and foot. Loss of the Achilles tendon reflex relates primarily to an S1 deficit. The Achilles tendon reflex is elicited by tap- ping the calcaneus tendon, which results in plantar flexion. The obturator internus and gluteus medius and minimus are responsible for abduction of the thigh and are innervated by nerves L4, L5, and S1 (with L5 usually dominant). Nerves L5, S1, and S2 are responsible for eversion of the foot (S1 dominant).

A 23-year-old man is admitted to the emergency department with a deep, bleeding stab wound of the pelvis. After the bleeding has been arrested, an MRI examination gives evidence that the right ventral pri- mary ramus of L4 has been transected. Which of the following problems will most likely be seen during physical examination? A. Reduction or loss of sensation from the me- dial aspect of the leg B. Loss of the Achilles tendon reflex C. Weakness of abduction of the thigh at the hip joint D. Inability to evert the foot E. Reduction or loss of sensation from the me- dial aspect of the leg and loss of Achilles ten- don reflex

E. The medial and lateral plantar nerves are branches of the tibial nerve. The tibial nerve passes posterior to the medial malleolus, within the tarsal tunnel

A 24-year-old female marathon runner complains of numbness and tingling over the plantar surface of her left foot and toes that radiates up the calf. Her symptoms increase with standing and at night, and they can be reproduced by percussion over the flexor retinaculum at the medial ankle. This condition most likely results from compression of which of the following nerves? A. Deep fibular B. Saphenous C. Superficial fibular D. Sural E. Tibial

C. A severe injury of the tibial nerve in the pop- liteal fossa would result in a dorsiflexed and everted foot because of the intact muscles of the extensor (anterior) and evertor (lateral) compartments of the leg. It would result also in some weakening of knee flexion because of loss of the gastrocnemius muscle, which flexes the knee and plantar flexes the foot. The hamstrings also flex the knee, so this function would not be lost. Plantar flexion at the ankle would be paralyzed with the loss of the gastrocnemius and so- leus, in addition to the flexors of the toes, and inver- sion by the tibialis posterior. Foot drop results from loss of the anterior compartment, innervated by the deep fibular (peroneal) nerve. GAS 584, 585; GA 13, 294-295, 322, 341-342

A 24-year-old female received a small-caliber bullet wound to the popliteal fossa from a drive-by assail- ant. The patient was admitted to the emergency department, where the surgeons recognized that the bullet had severed the tibial nerve. Such an injury would most likely result in which of the following? A. Inability to extend the leg at the knee B. Foot drop C. A dorsiflexed and everted foot D. A plantar flexed and inverted foot E. Total inability to flex the leg at the knee joint

E: Fibular (peroneal) artery. The posterior tib- ial artery supplies the posterior compartments of the leg and the plantar aspect of the foot. A major branch is the fibular (peroneal) artery, which supplies the fibular side of the poste- rior compartment of the leg. Choice A (Anterior tibial artery) is incorrect. The popliteal artery terminates by dividing into the anterior and posterior tibial arteries. In this case, blood will initially continue to flow into the anterior tibial artery and into the anterior compartment of the leg despite disruption of the posterior tibial artery. Choice B (Inferior medial genicu- lar artery) is incorrect. Both the inferior medial and inferior lateral genicular arteries are branches of the popliteal artery within the popliteal fossa, proximal to the terminal branch- ing of the popliteal artery. Thus, blood flow into these ves- sels is spared in this injury. Choice C (Dorsalis pedis artery) is incorrect. The dorsalis pedis artery is the direct continua- tion of the anterior tibial artery into the dorsum of the foot. Choice D (Popliteal artery) is incorrect. The popliteal artery runs through the popliteal fossa and ends by dividing into the anterior and posterior tibial arteries at approximately the lower border of the popliteus muscle.

A 25-year-old man suffers a gunshot wound to the calf that severs the posterior tibial artery at its origin. Which of the following vessels will not receive blood flow immediately fol- lowing the injury? (A) Anterior tibial artery (B) Inferior medial genicular artery (C) Dorsalis pedis artery (D) Poplitealartery (E) Fibular (peroneal) artery

C: Deltoid ligament. The injury in this patient is one of excessive eversion of the foot. Therefore, the liga- ment damaged is on the medial aspect of the ankle, where it is positioned to resist eversion. The deltoid ligament is a four-part structure that in total resembles the triangular Greek letter Delta. It covers the medial side of the ankle, extend- ing from its apex on the medial malleolus of the tibia down to its base on the navicular, calcaneus, and talus. It functions to resist excessive eversion of the foot. Due to its intrinsic strength, the deltoid ligament may not rupture but instead cause an avulsion fracture of the medial malleolus. Choice A (Plantar calcaneonavicular [spring] ligament) is incorrect. The plantar calcaneonavicular ligament is located in the plantar aspect of the foot, where it connects the sustentaculum tali of the calcaneus to the navicular bone. It helps support the head of the talus and the medial longitudinal arch of the foot. It is termed the spring ligament because it contains a high density of elastic fibers that provide spring to the foot during plan- tar flexion. Choice B (Calcaneofibular ligament) is incorrect. The calcaneofibular ligament, one of the three ligaments on the lateral aspect of the ankle, runs from the calcaneus to the lateral malleolus of the fibula, as its name indicates. It resists excessive inversion of the foot at the ankle joint, rather than eversion. Choice D (Anterior talofibular ligament) is incor- rect. This ligament, like the calcaneofibular ligament, resists excessive inversion of the foot at the ankle joint, rather than eversion. It connects the head and neck of the talus with the lateral malleolus of the fibula. The third component of the lateral ligament is the posterior talofibular ligament. Choice E (Plantar calcaneocuboid [long plantar] ligament) is incorrect. The plantar calcaneocuboid ligament is located in the plantar aspect of the foot. It is a relatively long structure that runs from the plantar side of the calcaneus to the cuboid and bases of the lateral metatarsal bones. It forms a deep canal for the tendon of the fibularis (peroneus) longus muscle and helps to support the lateral longitudinal arch of the foot.

A 25-year-old woman is brought to the emergency room in severe pain due to an ankle injury. She tells the attending physician she was wearing high-heel shoes, stepped off the curb into the street, lost her balance and landed awkwardly, causing her foot to turn extremely outward (eversion). Which of the following ligaments is most likely damaged? (A) Plantar calcaneonavicular (spring) ligament (B) Calcaneofibular ligament (C) Deltoidligament (D) Anteriortalofibularligament (E) Plantar calcaneocuboid (long plantar) ligament

C. In an inversion injury the most common liga- ment involvement comes from the anterior talofibular and calcaneofibular ligaments. The medial plantar nerve is medially located within the sole of the foot and might be injured by traction in an eversion injury, not an inversion injury. The posterior talofibular liga- ment is located posteriorly and is not usually injured in an inversion injury. The deltoid ligament is located medially and would be injured with an eversion in- jury; it is so strong, however, that eversion is more likely to fracture the medial malleolus rather than tear the deltoid ligament.

A 27-year-old female tennis pro injured her ankle during the quarterfinal match. A physical examination at the outpatient clinic revealed a severe inversion sprain of the ankle. Which of the following structures is most commonly damaged in such injuries? A. Medial plantar nerve B. Tibial nerve C. Anterior talofibular ligament D. Posterior talofibular ligament E. Deltoid ligament

C the PCL prevents posterior dislocation of the tibia relative to the femur

A 28-year-old female pedestrian is rushed to the Emergency Department by ambulance after being hit by a car that failed to stop at an intersection. During the physical exam it is noted that her right tibia can be pushed posteriorly relative to her right femur, compared to her left lower limb. Injury to which of the following most likely accounts for this clinical finding? A. Lateral collateral ligament B. Medial collateral ligament C. Posterior cruciate ligament D. Anterior cruciate ligament E. Lateral meniscus F. Medial meniscus

E. lateral meniscus The posterior cruciate ligament prevents posterior drawer of the tibia relative to the femur; the anterior cruciate ligament prevents anterior drawer of the tibia relative to the femur.

A 28-year-old female was hit by a car that failed to stop at an intersection. During the physical exam you note that her right tibia can be pushed posteriorly relative to the femur beyond its normal limits. Injury to which of the following can account for this clinical finding? A. fibular collateral ligament B. medial collateral ligament C. posterior cruciate ligament D. anterior cruciate ligament E. lateral meniscus

E. The lateral femoral cutaneous nerve leaves the pelvis laterally, about 2 cm medial to the anterior superior iliac spine, passing beneath, or through, the inguinal ligament. As a consequence of its site of exit, any tension upon or compression of the inguinal liga- ment can affect the nerve. If it is thus affected, the individual may feel burning sensations or pain along the lateral aspect of the thigh, which is the region of distribution of the nerve. Obesity, sudden weight loss, wearing a heavy gun belt, wearing trousers that are too tight (Calvin Klein syndrome), or having someone sitting on another's lap for an extended period of time can lead to meralgia paresthetica, the painful lateral thigh. The femoral nerve emerges from beneath the middle of the inguinal ligament and is not usually af- fected by similar traction or compression. The obtura- tor nerve leaves the pelvis through the obturator ca- nal and enters the thigh deeply in a protected location. It innervates the adductor muscles and supplies sen- sation on the medial aspect of the thigh. The fibular (peroneal) division of the sciatic nerve supplies the muscles of the anterior and lateral compartments of the leg and provides sensory fibers for the dorsum and lateral side of the foot. The superior gluteal nerve provides motor supply to the gluteus medius and minimus muscles. GAS 465; GA 187

A 29-year-old male police officer is examined in a neighborhood clinic, with a complaint of discomfort in the lateral thigh. During the taking of the patient's medical history the physician observes that the police- man is rather overweight and that he is wearing a heavy leather belt, to which numerous objects are attached, including his empty holster. After a thorough physical examination a tentative diagnosis is advanced of meralgia paresthetica. Which of the following nerves is most likely involved? A. Superior gluteal B. Femoral C. Obturator D. Fibular (peroneal) division of sciatic E. Lateral femoral cutaneous

D The lateral cutaneous nerve may be compressed where it passes between the inguinal ligament and sartorius m. (meralgia paresthetica). This injury is somewhat common in individuals with professions that require belts laden with heave objects (police officers, plumbers, contractors etc)

A 29-year-old male police officer presents with a complaint of discomfort in his lateral thigh. Physical examination revealed an absence of muscular deficits and that the area of discomfort was restricted to the lateral thigh. Which of the following nerves is likely injured in this patient? A. Femoral B. llioinguinal C. Inferior gluteal D. Lateral femoral cutaneous E. Saphenous

B. Injury to the superior gluteal nerve results in a characteristic motor loss, with paralysis of gluteus me- dius and minimus. In addition to their role in abduct- ing the thigh, the gluteus medius and minimus func- tion to stabilize the pelvis: When the patient is asked to stand on the limb of the injured side, the pelvis de- scends on the opposite side, indicating a positive Tren- delenburg test. The gluteal, or lurching, gait that results from this injury is characterized by the pelvis drooping to the unaffected side when the opposite leg is raised. In stepping forward, the affected individual leans over the injured side when lifting the good limb off the ground. The uninjured limb is then swung forward. The gluteus maximus, supplied by the inferior gluteal nerve, is the main muscle responsible for allowing a person to rise to a standing position (extending the flexed hip). Spinal nerve roots L1 and L2 and the femoral nerve are responsible for hip flexion. Injury to the left superior gluteal nerve would result in sagging of the right side of the pelvis when the affected indi- vidual stands on the left limb. The hamstring muscles, responsible for flexing the knees to allow a person to sit down from a standing position, are innervated by the tibial branch of the sciatic nerve.

A 30 year old male suffered a superior gluteal nerve injury in a motorcycle crash in which his right lower limb was caught beneath the bike. He is stabilized in the emergency department. Later he is examined and he exhibits a waddling gait and a positive Trendelenburg sign. Which of the following would be the most likely physical finding in this patient? A. Difficulty in standing from a sitting position B. The left side of the pelvis droops or sags when he attempts to stand with his weight supported just by the right lower limb. C. The right side of the pelvis droops or sags when he attempts to stand with his weight supported just by the left lower limb. D. Weakened flexion of the right hip E. Difficulty in sitting from a standing position

B. Pott's fracture is a rather archaic term for a fracture of the fibula at the ankle. The term is often used to indicate a bimalleolar fracture of fibula and tibia, perhaps with a tear in the medial collateral liga- ment, allowing the foot to be deviated laterally. (The medial malleolus will often break before the deltoid ligament tears.) This fracture is also known as Dupuy- tren's fracture. The fracture results from abduction and lateral rotation of the foot in extreme eversion. There can also be breaking of the posterior aspect of the dis- tal tibia. The spring ligament, also known as the plan- tar calcaneonavicular ligament, extends from the calca- neus to the navicular bone and is a part of the medial longitudinal arch. This ligament would not be affected in eversion or inversion of the ankle. The plantar liga- ment, which is composed of the long and short plantar ligaments, supports the lateral longitudinal arch of the foot and would therefore not be affected by inversion or eversion of the foot. The calcaneofibular ligament runs from the calcaneus to the fibula. It would be in- jured during inversion of the foot, not in eversion, as is the case in a Pott fracture.

A 32-year-old male basketball player comes down hard on his ankle. He is admitted to the outpatient clinic, and radiographic examination reveals a Pott's fracture. What ligament is most likely injured? A. Calcaneofibular ligament B. Deltoid ligament C. Spring ligament D. Plantar ligament E. Long plantar ligament

E: Vertical group of superficial inguinal. The vertical group of superficial inguinal lymph nodes receives superficial lymph vessels from the territory drained by the great saphenous vein (including the medial aspect of the thigh) and lies along its termination near the saphenous hiatus. Efferent lymphatic vessels from this group of super- ficial inguinal nodes drain into deep inguinal nodes. Given the location of the injury and the patient's presentation, this group of lymph nodes is most likely to receive the initial drainage from the infected wound. Choice A (Popliteal) is incorrect. The popliteal nodes are located in the popliteal fossa and receive lymphatic drainage from the lateral side of the leg and foot, which corresponds to the area drained by the small saphenous vein, and from deep lymph vessels accom- panying the anterior and posterior tibial arteries. The efferent lymphatic vessels leaving the popliteal nodes drain into deep lymph vessels of the lower limb that parallel the major vessels before reaching the deep inguinal nodes. Choice B (External iliac) is incorrect. The external iliac lymph nodes lie along the external iliac vessels above the superior pelvic aperture and receive lymphatic drainage from the inguinal lymph nodes, abdominal wall below the level of the umbilicus, and the pel- vic viscera. Efferent vessels from the external iliac nodes drain into common iliac nodes. These nodes are not the first nodes affected in this patient due to the site of the injury (medial thigh). Choice C (Deep inguinal) is incorrect. The deep ingui- nal nodes receive lymph from deep lymphatic vessels in the lower limb that travel with the arteries, from the superficial inguinal nodes (horizontal and vertical groups), from the popliteal nodes, and from the glans and body of the clitoris or penis. Efferent vessels from the deep inguinal nodes drain into external iliac nodes. Though the deep inguinal nodes could be involved with this infection, they would not be the first nodes affected in this patient due to the site of the injury (medial thigh). Choice D (Horizontal group of superficial inguinal) is incorrect. The horizontal group of superficial inguinal lymph nodes is located approximately 2 cm below the inguinal liga- ment and receives lymphatic drainage from the lateral but- tocks, lower anterior abdomen wall, and the perineum. An infected cut on the medial thigh would not send lymph to this group of nodes.

A 32-year-old male farmer cuts the medial aspect of his midthigh when climbing over a barbwire fence. Though he bandages the wound, he reports to the ER 5 days later with an infected wound, high fever (102.7°), and lymphadenitis (swollen lymph nodes). Given the location of the injury, which groups of nodes would be the first to receive drainage from the infected wound? (A) Popliteal (B) External iliac (C) Deepinguinal (D) Horizontal group of superficial inguinal (E) Vertical group of superficial inguinal

A. The gluteus maximus is innervated by the inferior gluteal nerve, and this muscle is responsible for extension and lateral rotation of the thigh. It is the primary muscle used to rise from a seated position. The gluteus minimus is innervated by the superior gluteal nerve and is responsible for abduction of the thigh. Hamstring muscles are innervated by the tibial portion of the sciatic nerve, and these are responsible for extension of the thigh and flexion of the leg. The iliopsoas muscle is innervated by L1 and L2 and the femoral nerve, and it flexes the thigh. The obturator internus is innervated by the nerve to the obturator internus and is a lateral rotator of the thigh.

A 32-year-old patient received a badly placed in- tramuscular injection to the posterior part of his gluteal region. The needle injured a motor nerve in the area. Later, he had great difficulty rising to a standing posi- tion from a seated position. Which muscle was most likely affected by the injury? A. Gluteus maximus B. Gluteus minimus C. Hamstrings D. Iliopsoas E. Obturator internus

D the sciatic nerve is at risk of injury in posterior dislocation of the hip. The tibial nerve component of the sciatic nerve innervates the hamstrings, which flex the knee.

A 34-year-old man sustains a posterior dislocation of the hip in an automobile accident. After reduction, the lower extremity is examined for possible weakness or paralysis of muscles. Which of the following movements of the lower extremity is likely to be affected in this patient? A. Hip adduction B. Hip flexion C. Knee extension D. Knee flexion

C. When the popliteus contracts, it rotates the distal portion of the femur in a lateral direction. It also draws the lateral meniscus posteriorly, thereby pro- tecting this cartilage as the distal femoral condyle glides and rolls backward, as the knee is flexed. This allows the knee to flex and therefore serves in unlock- ing the knee. The biceps femoris is a strong flexor of the leg and laterally rotates the knee when it is in a position of flexion. The gastrocnemius is a powerful plantar flexor of the foot. The semimembranous, similar to the biceps femoris, is a component of the hamstring muscles and is involved in extending the thigh and flexing the leg at the knee joint. The rectus femoris is the strongest quadriceps muscle in extend- ing the leg at the knee. GAS 589, 590; GA 9, 285, 321

A 34-year-old power lifter visits the outpatient clinic because he has difficulty walking. During physi- cal examination it is observed that the patient has a problem unlocking the knee joint to permit flexion of the leg. Which of the following muscles is most likely damaged? A. Biceps femoris B. Gastrocnemius C. Popliteus D. Semimembranosus E. Rectus femoris

E: Sciatic nerve. The sciatic nerve is formed by the anterior rami of L4-S3 and is located in the inferior medial quadrant of the buttock. This nerve supplies the muscles in the posterior compartment of the thigh and bifurcates into the tibial nerve and common fibular nerves in the popliteal fossa. The patient exhibits damage to the L4-S1 distribution of this nerve, which would severely limit inversion (L4, L5), eversion (L5, S1), and dorsiflexion (L4, L5) of the foot at the ankle joint. The inability to dorsiflex the foot also has led to foot drop. This prisoner received an improperly placed gluteal IM injection, which either directly damaged his sciatic nerve or the damage to the nerve was caused secondarily due to infec- tion (possibly from an improperly sanitized needle). Properly administered gluteal IM injections are placed posterior to the anterior superior iliac spine and anterior to the tubercle of the iliac crest along the superior border of the gluteus maximus muscle (see diagram on next page). These injections pen- etrate skin, fascia, and muscles, which allows absorption of the injected substance into the IM veins located in the area of the tensor fasciae latae muscle. Choice A (Superior gluteal nerve) is incorrect. The superior gluteal nerve supplies motor innervation to the gluteus medius, gluteus minimus, and ten- sor fasciae latae muscles. Loss of this innervation would lead to weakness in abducting and medially rotating the thigh at the hip joint. These muscles are also responsible for keeping the pelvis level during the swing phase of gait. Though the superior gluteal nerve is formed by the anterior rami of L4-S1, damage to this nerve would not cause the paresis (weakness) seen in this patient at the ankle joint. Choice B (Common fibular nerve) is incorrect. The common fibular (peroneal) nerve is a terminal branch of the sciatic nerve that usually does not arise until the sciatic nerve bifurcates in the apex of the popliteal fossa. This nerve further divides into the deep and superficial fibular nerves, which supply the motor innervation to the anterior and lateral compartments of the leg, respec- tively. Damage to the common fibular nerve would lead to the symptoms seen in this patient (i.e., weakness in inversion, eversion, and dorsiflexion of the foot at the ankle joint as well as foot drop). However, a gluteal IM injection would not affect this nerve directly due to its origin, which is usually in the apex of the popliteal fossa. Choice C (Tibial nerve) is incor- rect. The tibial nerve is a terminal branch of the sciatic nerve that usually does not arise until the sciatic nerve bifurcates in the apex of the popliteal fossa. This nerve supplies the posterior compartment of the leg and is important in plan- tar flexion of the foot at the ankle joint. Weakness in plantar flexion was not noted in this patient, and more importantly, a gluteal IM injection would not affect this nerve directly due to its origin, which is usually in the popliteal fossa. Choice D (Inferior gluteal nerve) is incorrect. The inferior gluteal nerve innervates the gluteus maximus and is formed by the anterior rami of L5-S2. This muscle is involved with lateral rotation and extension of the thigh at the hip joint, especially when the thigh is in a flexed position (rising from a sitting position or climbing stairs). Damage to the inferior gluteal nerve would not produce weakness in movements of the ankle joint.

A 35-year-old male prisoner received a right gluteal intramus- cular (IM) injection during a visit to the infirmary. Following the injection, the man experienced a painful, swollen right leg. Within a month, he complained that his right leg started to shrink. Examination revealed muscle wasting with fasciculations in the L4-S1 distribution and marked weakness in dorsiflexion, inversion, and eversion at the ankle joint. He also exhibited a typical high-steppage gait indicating right foot drop. What nerve was most likely damaged during the gluteal IM injection? (A) Superior gluteal nerve (B) Common fibular nerve (C) Tibialnerve (D) Inferior gluteal nerve (E) Sciatic nerve

E. cremasteric reflex. The cremasteric reflex is a cutaneous reflex that tests the integrity of the L1-2 spinal cord segments. Lightly stroking the superior and medial parts of the thigh stimulates the sensory fibers of the ilioinguinal nerve (the afferent limb of this reflex), which, in turn, stimulates the contraction of the cremaster muscle to pull up the testis on the ipsilateral side. This efferent limb of the reflex is acti- vated by the motor fibers of the genital (cremasteric) branch of the genitofemoral nerve. The genitofemoral nerve is formed by the ventral rami of L1-2. Choice A (Anocutaneous reflex) is incorrect. The anocutaneous reflex (or anal wink test) is a cutaneous reflex that tests the integrity of the S2-4 spinal cord segments due to the innervation of this aspect of the perineum by the pudendal nerve. Choice B (Patellar reflex) is incor- rect. The patellar reflex is a deep tendon reflex that confirms the integrity of the L2-4 spinal segments. Striking the patellar tendon elicits contraction of the quadriceps muscles, which are innervated by the femoral nerve, comprised of the ventral rami of L2-4. Choice C (Plantar reflex) is incorrect. The plan- tar (Babinski) reflex is a cutaneous reflex that confirms the integrity of the corticospinal tract within the central nervous system. Rubbing the lateral side of the sole of the foot from the heel to the toes with a blunt instrument should cause a normal adult response, which is flexion of the toes and ever- sion of the foot. Choice D (Calcaneal reflex) is incorrect. The calcaneal (Achilles or ankle jerk) reflex is a deep tendon reflex that confirms the integrity of the tibial nerve and the S1-2 spinal segments, from which this nerve is primarily derived. The tibial nerve is a terminal branch of the sciatic nerve that supplies the posterior compartment of the leg, including the superficial compartment containing the gastrocnemius and soleus muscles, which contract in a normal response to this reflex.

A 36-year-old man arrives at the ER unconscious and with a suspected spinal cord injury after being involved in a motor vehicle accident. If the physician wants to localize the spinal cord lesion, what reflex would test the integrity of the L1-2 spinal cord segment? (A) Anocutaneousreflex (B) Patellar reflex (C) Plantarreflex (D) Calcanealreflex (E) Cremasteric reflex

A. The talocrural (tibiotalar, ankle) joint is a hinge-type synovial joint between the tibia and talus. It permits dorsiflexion and plantar flexion, and frac- ture of this joint would affect these movements.

A 37-year-old male is admitted to the hospital after an injury to his foot while playing flag football with friends on a Saturday morning. A series of radio- graphs demonstrates a fracture involving the talocrural (tibiotalar, ankle) joint. Which movements are the major ones to be affected by this injury? A. Plantar flexion and dorsiflexion B. Inversion and eversion C. Plantar flexion, dorsiflexion, inversion, and eversion D. Plantar flexion and inversion E. Dorsiflexion and eversion

A. The plantar calcaneonavicular ligament (spring ligament) supports the head of the talus and maintains the longitudinal arch of the foot. A fracture of the cuboid bone would not disrupt the longitudinal arch of the foot. Interruption of the plantar aponeuro- sis is not the best answer because this aponeurosis provides only passive support, unlike the spring liga- ment. A sprain of the anterior talofibular ligament would result from an inversion injury of the ankle and would not disrupt the longitudinal arch of the foot. A sprain of the deltoid ligament results from eversion of the ankle joint and would not disrupt the longitudinal arch of the foot.

A 41-year-old man is admitted to the emergency department with a swollen and painful foot. Radio- graphic examination reveals that the head of the talus has become displaced inferiorly, thereby causing the medial longitudinal arch of the foot to fall. What would be the most likely cause in this case? A. Tearing of the plantar calcaneonavicular (spring) ligament B. Fracture of the cuboid bone C. Interruption of the plantar aponeurosis D. Sprain of the anterior talofibular ligament E. Sprain of the deltoid ligament

D. The second perforating branch of the pro- funda femoris (deep femoral) artery commonly pro- vides the nutrient artery to the femur, a vessel that passes through a rather large foramen to enter the proximal part of the shaft. The deep circumflex branch of the external iliac passes around the medial aspect of the iliac crest, also supplying the lower lateral part of the anterior abdominal wall. The ace- tabular branch of the obturator artery supplies tis- sues in the hip socket, usually including a branch to the ligament of the head of the femur. The lateral circumflex femoral branch of the deep femoral artery supplies the vastus lateralis muscle. The medial cir- cumflex femoral branch of the deep femoral artery supplies proximal adductor musculature and the re- gion of the hip joint, including the neck and head of the femur. GAS 570-571; GA 292

A 42-year-old male sign painter is admitted to the emergency department after falling to the sidewalk from his ladder. Radiographic examination reveals a fracture of the proximal femur. Which of the following arteries supplies the proximal part of the femur? A. Deep circumflex iliac B. Acetabular branch of obturator C. Lateral circumflex femoral D. A branch of profunda femoris E. Medial circumflex femoral

A. The lumbosacral trunk consists of fibers from a portion of the ventral ramus of L4 and all of the ventral ramus of L5 and provides continuity between the lumbar and sacral plexuses. The deep fibular (peroneal) nerve receives supply from segments of L4, L5, and S1. It supplies the extensor hallicus lon- gus, and extensor digitorum longus, the main func- tions of which are extension of the toes and dorsiflex- ion of the ankle. L5 is responsible for cutaneous innervation of the dorsum of the foot. Injury to L4 would affect foot inversion by the tibialis anterior. Injury to L4 in the lumbosacral trunk would not af- fect the patellar tendon reflex, for these fibers are delivered by the femoral nerve. Therefore, an injury to the lumbosacral trunk would result in all of the patient's symptoms. Nerve root injury at L5 and S1 would result in loss of sensation of the plantar aspect of the foot and motor loss of plantar flexion, with weakness of hip extension and abduction. The fibu- laris (peroneus) longus and brevis are supplied by the superficial fibular (peroneal) nerve, which is composed of fibers from segments L5, S1, and S2; these are responsible for eversion of the foot (espe- cially S1). Transection of the fibular (peroneal) divi- sion of the sciatic nerve would result in loss of func- tion of all the muscles of the anterior and lateral compartments of the leg. Injury to the sciatic nerve will affect hamstring muscles and all of the muscles below the knee. Injury to the tibial nerve causes loss of plantar flexion and impaired inversion.

A 42-year-old man is admitted to the emergency department after his automobile hit a tree, and he is treated for a pelvic fracture and several deep lacera- tions. Physical examination reveals that dorsiflexion and inversion of the left foot and extension of the big toe are very weak. Sensation from the dorsum of the foot, skin of the sole, and the lateral aspect of the foot has been lost and the patellar reflex is normal. The foot is everted and plantar flexed. Which of the following structures is most likely injured? A. The lumbosacral trunk at linea terminalis B. L5 and S1 spinal nerves torn at the interverte- bral foramen C. Fibular (peroneal) division of the sciatic nerve at the neck of the fibula D. Sciatic nerve injury at the "doorway to the gluteal region" E. Tibial nerve in popliteal fossa

C. Entrapment compression of all or part of the sciatic nerve by the piriformis can mimic disk hernia- tion, most commonly resembling compression of spi- nal nerve S1. This results in pain down the posterior aspect of the thigh and leg and the lateral side of the foot. In this case, loss of sensation over the dorsum of the foot and weakness of foot extension, in addition to eversion, indicate that more than S1 is involved. Foot drop would be anticipated with fibular (peroneal) nerve involvement. As noted also in a previous ques- tion, compression of the common fibular (peroneal) division of the sciatic nerve by the piriformis gives rise to the clinical condition known as piriformis entrap- ment. This condition is associated with point pain in the gluteal area, pain in the posterior part of the limb, and possible weakness of muscles in the lateral and anterior compartments of the leg. It can be confused with herniated disk (L5) compression of S1 and sciat- ica. Paralysis of plantar flexion occurs with a lesion of the tibial division of the sciatic nerve or the tibial nerve. Paralysis of the quadriceps is associated with pathology of the femoral nerve. Clonic contraction of the adductors could result from obturator nerve prob- lems. Anterior cluneal nerves (sensory to anterior gluteal region) arise from the iliohypogastric nerve. GAS 118; GA 13, 238, 282-283, 294-296

A 43-year-old female is examined by a neurolo- gist, to whom she complains of pain in her lower limb of 6 months' duration. She has pain in the gluteal area, thigh, and leg. The neurologist observes reduced sensa- tion over the dorsum and lateral side of the involved foot and some weakness in foot dorsiflexion and ever- sion. A diagnosis of a piriformis entrapment syndrome is made, with compression of the fibular (peroneal) division of the sciatic nerve. Which of the following conditions did the neurologist also most likely find dur- ing her physical examination of the patient? A. Paralysis of plantar flexion B. Instability of the knee, due to paralysis of the quadriceps femoris C. Foot drop D. Spasm or clonic contractures of the adductor musculature of the thigh E. Loss of sensation in the gluteal area, by paralysis of anterior cluneal nerves

E. The vastus lateralis muscle is located on the lateral aspect of the thigh. The distal portion of this muscle lies superficial to the proximal part of the lat- eral aspect of the joint capsule of the knee. When a needle is inserted superiorly and laterally to the pa- tella, it penetrates the vastus lateralis muscle on its course to the internal capsule. The short head of bi- ceps femoris has its origin on the posterior aspect of the femur, merges with the long head of the biceps femoris, and inserts on the head of the fibula. The rectus femoris passes longitudinally on the medial aspect of the femur and inserts on the tibial tuberos- ity, via the patellar tendon, or quadriceps tendon. A needle inserted laterally to the patella would not pen- etrate this muscle. The sartorius originates on the anterior superior iliac spine and forms part of the pes anserinus, which inserts on the medial aspect of the proximal part of the tibia. A needle inserted laterally to the patella would not penetrate this muscle. GAS 561-563; GA 8, 272, 280-281, 285-288, 296, 307, 320, 323-324

A 43-year-old man visits the outpatient clinic with a painful, swollen knee joint. The patient's history reveals chronic gonococcal arthritis. A knee aspiration is ordered for bacterial culture of the synovial fluid. A standard suprapatellar approach is used, and the nee- dle passes from the lateral aspect of the thigh into the region immediately proximal to and deep to the patella. Through which of the following muscles would the needle pass? A. Adductor magnus B. Short head of biceps femoris C. Rectus femoris D. Sartorius E. Vastus lateralis

E. The tibial nerve is responsible for innervating the posterior compartment of the leg. These muscles are responsible for knee flexion, plantar flexion, and intrinsic muscle functions of the foot. Compression of this nerve can affect plantar flexion of the foot. Dorsi- flexion of the foot would be compromised if the deep fibular (peroneal) nerve were compressed by this Baker cyst. Flexion of the thigh is a function of mus- cles supplied by lumbar nerves and the femoral nerve. The deep fibular (peroneal) nerve is also responsible for extension of the digits, whereas the femoral nerve is responsible for extension of the leg.

A 45-year-old male presents at the local emergency clinic with the complaint of a painful knee and difficulty in walking. A CT scan examination reveals a very large cyst in the popliteal fossa compressing the tibial nerve. Which movement will most likely be affected? A. Dorsiflexion of the foot B. Flexion of the thigh C. Extension of the digits D. Extension of the leg E. Plantar flexion of the foot

C. The Achilles tendon reflex is a function of the triceps surae muscle, composed of insertion of the gastrocnemius and soleus muscles on the calcaneus. The innervation is provided primarily by spinal nerve S1. The S1 root leaves the vertebral column at the S1 foramen of the sacrum, but a herniated disk at the L5-S1 intervertebral space puts the S1 root under ten- sion, resulting in pain and possible weakness or pa- ralysis of S1-supplied muscles, especially the plantar flexors. A disk lesion at L3-4 would affect the L4 spi- nal nerve (affecting foot inversion and extension); a lesion at L4-5 would cause problems with L5 (hip abduction and knee flexion). A disk lesion at S1-2 in the sacrum is improbable, unless there was lumbari- zation of the S1 vertebra. The gluteal crush syndrome usually occurs when a patient has been lying uncon- scious and unmoving on a hard surface for an ex- tended period of time. GAS 523-524; GA 5

A 45-year-old man is admitted to the emergency department after experiencing a sharp pain while lift- ing a box of books. He told the physician that he "felt the pain in my backside, the back of my thigh, my leg, and the side of my foot." During physical examination it is observed that his Achilles tendon jerk is weakened on the affected side. Which is the most likely cause of injury? A. Disk lesion at L3-4 B. Disk lesion at L4-5 C. Disk lesion at L5-S1 D. Disk lesion at S1-2 E. Gluteal crush syndrome of sciatic nerve or piriformis syndrome

C. The lateral plantar nerve innervates the interos- sei and adductor hallucis. These losses would be obvi- ous when the patient attempts to abduct and adduct the toes. Sensation would be absent over the lateral side of the sole, the fifth and fourth toes, and half of the third toe. The medial plantar nerve provides sensation over the plantar surface of the first and second toes and half of the third toe as well as function of the so-called LAFF muscles: first lumbrical abductor hallucis, flexor hallu- cis brevis, and flexor digitorum brevis.

A 46-year-old woman stepped on a broken wine bottle on the sidewalk and the sharp glass entered the posterior part of her foot. The patient was admitted to the hospital, and a physical examination concluded that her lateral plantar nerve had been transected (cut through). Which of the following conditions will most likely be confirmed by physical examination? A. Loss of sensation over the plantar surface of the third toe B. Paralysis of the abductor hallucis C. Paralysis of the interossei and adductor hallucis D. Flexor hallucis brevis paralysis E. Flexor digitorum brevis paralysis

A. The femoral ring is the abdominal opening of the femoral canal. A femoral hernia passes through the femoral ring into the femoral canal deep and infe- rior to the inguinal ligament. It can appear as a bulg- ing at the saphenous hiatus (fossa ovalis) of the deep fascia of the thigh, the hiatus through which the sa- phenous vein passes to the femoral vein. The superfi- cial inguinal ring is the triangular opening in the aponeurosis of the external abdominal oblique and lies lateral to the pubic tubercle. The deep inguinal ring lies in the transversalis fascia lateral to the infe- rior epigastric vessels. Herniation into either of these two openings is associated with an inguinal hernia. The obturator canal, a bony opening between the superior and inferior ramus of the pubic bone, is the site of an obturator hernia.

A 49-year-old construction worker is admitted to the emergency department with a painful lump on the proximal medial aspect of his thigh. Radiographic and physical examinations reveal that the patient has a herniation of abdominal viscera beneath the inguinal ligament into the thigh. Through which of the following openings will a hernia of this type initially pass to extend from the abdomen into the thigh? A. Femoral ring B. Superficial inguinal ring C. Deep inguinal ring D. Fossa ovalis E. Obturator canal

B. Contraction of the gastrocnemius on the broken calcaneus would increase the pain because the gastroc- nemius inserts with the soleus upon that bone, via the calcaneal tendon, or tendo Achilles. The flexor digito- rum profundus passes the ankle medially to enter the sole of the foot, where it inserts upon the distal phalanges. The tibialis posterior, likewise, passes under the medial malleolus, with complex insertions upon the navicular bone, cuneiform bones, metatarsal bones, and the cuboid bone. The tibialis anterior, a muscle of the anterior leg compartment, inserts upon the navicu- lar bone and, with the tibialis posterior, is a strong in- vertor of the foot. The fibularis (peroneus) longus is a muscle of the lateral compartment of the leg. It passes under the lateral malleolus, entering the sole of the foot by crossing the lateral surface of the calcaneus, and inserts primarily into the medial cuneiform and base of the first metatarsal bone.

A 49-year-old male worker fell from a ladder, with his weight impacting on the heels of his feet. Radiographic examination reveals comminuted calcaneal fractures. After the injury the contraction of which one of the following muscles could most likely increase the pain in the injured foot? A. Flexor digitorum profundus B. Gastrocnemius C. Tibialis posterior D. Tibialis anterior E. Fibularis (peroneus) longus

D. The great saphenous vein is commonly used in coronary artery bypass grafts. Because branches of the saphenous nerve cross the vein in the distal part of the leg, the nerve can be torn out of the limb if the vein is stripped from the ankle to the knee. Stripping the vein in the opposite direction can protect the nerve and lessen the postoperative discomfort of pa- tients. The saphenous nerve is responsible for cutane- ous innervations on the medial surface of the leg and the medial side of the foot. Injury to this nerve will result in a loss of sensation and also can create chronic dysesthesias in the area. The common fibular (peroneal) nerve bifurcates at the neck of the fibula into the superficial and deep fibular (peroneal) nerves, which continue on to innervate the lateral and ante- rior compartments of the leg, respectively. These nerves are lateral and therefore not associated with the great saphenous vein. The lateral sural nerve is a cutaneous nerve that arises from the junction of branches from the common fibular (peroneal) nerve and tibial nerve and innervates the skin on the poste- rior aspect of the leg and lateral side of the foot. This nerve is often harvested for nerve grafts elsewhere in the body. The tibial nerve is a terminal branch of the sciatic nerve that continues deep in the posterior compartment of the leg.

A 49-year-old man underwent a coronary bypass graft procedure using the great (long) saphenous vein. Postoperatively the patient complains of pain and general lack of normal sensation on the medial surface of the leg and foot on the limb from which the graft was harvested. Which nerve was most likely injured during surgery? A. Common fibular (peroneal) B. Superficial fibular (peroneal) C. Lateral sural D. Saphenous E. Tibial

B. An injury to L4 would cause weakness in the patellar reflex and loss of cutaneous innervation to the medial side of the leg. Patellar reflex is used to test L2 to L4 nerve integrity. The motor side of the reflex is primarily derived from spinal nerves L2 and L3, whereas the sensory side of the arc is said to be prin- cipally from L4. The L4 spinal nerve supplies the L4 dermatome on the medial side of the leg and foot, by way of the saphenous nerve. It also supplies foot inver- sion, a function of the tibialis anterior and tibialis pos- terior muscles; the first is supplied by the deep fibular (peroneal) nerve, and the second supplied by the tibial nerve. Foot dorsiflexion is weakened because of partial denervation of the extensor digitorum longus, but L5 is still contributing to that function. The foot is everted because the S1-supplied (by the superficial fibular nerve) fibularis (peroneus) longus and brevis are unop- posed. The Achilles reflex is also primarily supplied by S1. Hip movements are produced primarily by L5- and S1-supplied muscles, as is knee flexion. GAS 522-523; GA 34, 346-347

A 55-year old woman is admitted to the emergency department after an automobile crash. Physical examination reveals that the patient's foot is everted and she cannot invert it. A weakness in dorsiflexion and inversion of the foot is noted. Her ipsilateral patellar reflex is reduced in quality, although the Achilles tendon reflex is brisk. Knee extension is almost normal, as are all hip movements and knee flexion. Sensation is greatly reduced on the medial side of the leg. Which of the following nerves is most likely injured? A. Femoral nerve B. L4 spinal nerve C. L4 and L5 spinal nerves D. Common fibular (peroneal) nerve E. Tibial nerve

C. The L4 ventral primary ramus contributes fibers to all nerves of the leg. It contributes relatively more to the femoral nerve, than it does to the tibial nerve.

A 55-year-old woman is admitted to the emergency department after an automobile crash. Physical examination reveals that the patient's foot is everted and she cannot invert it. A weakness in dorsiflexion and inversion of the foot is noted. Her ipsilateral patellar reflex is reduced in quality, although the Achilles tendon reflex is brisk. Knee extension is almost normal, as are all hip movements and knee flexion. Sensation is greatly reduced on the medial side of the leg. Which of the following nerves is most likely? A. Common fibular nerve B. Femoral nerve C. L4 spinal nerve D. Tibial nerve

E: Gracilis. All the nerves supplying the lower limb originate within the abdominal and/or pelvic cavities, from the lumbar and/or sacral plexuses. Therefore, all these nerves must have positional relationships to and must pen- etrate through the abdominal or pelvic walls in order to reach the lower limb. The obturator nerve crosses the lateral wall of the pelvis on its way to the obturator canal and into the lower limb, and may be damaged in surgery or trauma to the lateral pelvic wall. Ultimately, it supplies the muscles in the medial compartment of the thigh, including the gracilis. Trauma to the efferent fibers within the obturator nerve may produce spasms or dysfunction in any of these muscles. Choice A (Sartorius) is incorrect. The sartorius is a member of the anterior com- partment of the thigh, controlled by the femoral nerve. The femoral nerve does not cross the lateral pelvic wall in its path to the lower limb. Instead, it runs lateral and parallel to the psoas major muscle, outside the true pelvic cavity. Choice B (Biceps femoris) is incorrect. The biceps femoris is located in the posterior compartment of the thigh. It is supplied by both the tibial and common fibular (peroneal) nerves. These nerves exit the pelvis through the greater sciatic foramen as components of the sciatic nerve. Neither nerve is related to the lateral pelvic wall. Choice C (Tensor muscle of fascia lata) is incorrect. The tensor muscle of fascia lata (tensor fasciae latae) is innervated by the superior gluteal nerve. This nerve also exits the pelvis through the greater sciatic foramen and is well removed from the lateral pelvic wall. Choice D (Vastus media- lis) is incorrect. The vastus medialis is part of the quadriceps femoris muscles in the anterior compartment of the thigh. It is supplied by the femoral nerve, which does not cross the lateral pelvic wall in its path to the lower limb. Instead, it runs lateral and parallel to the psoas major muscle, outside the true pelvic cavity.

A 55-year-old woman recently had pelvic surgery during which cancerous lymph nodes were removed from the lateral wall of her pelvis. During a postoperative examination, she says she has been having painful muscle spasms in her thigh. Which of the following muscles is most likely involved? (A) Sartorius (B) Biceps femoris (C) Tensor muscle of fascia lata (D) Vastusmedialis (E) Gracilis

B. The obturator nerve arises from the lumbar plexus and enters the thigh through the obturator canal. This nerve is responsible for innervation of the medial compartment of the thigh (adductor compart- ment). Injury to this nerve can result in weakened adduction and difficulty walking. The femoral nerve innervates muscles of the anterior compartment of the thigh that are responsible for hip flexion and leg extension. The sciatic nerve branches into the common fibular (peroneal) and tibial nerves. The com- mon fibular (peroneal) nerve branches into the deep and superficial branches of the fibular (peroneal) nerve responsible for innervation of the anterior and lateral compartments of the leg, respectively. The tibial nerve innervates the muscles of the posterior compartment of the thigh and leg, which are respon- sible for extension of the hip, flexion of the leg, and plantar flexion of the foot.

A 56-year-old male with advanced bladder carcinoma suffers from difficulty while walking. Muscle testing reveals weakened adductors of the right thigh. Which nerve is most likely being compressed by the tumor to result in walking difficulty? A. Femoral B. Obturator C. Common fibular (peroneal) D. Tibial E. Sciatic

D. sural the sural nerve innervates the posterolateral aspect of the calf and the lateral ankle posterior to the lateral malleolous

A 58-year-old male farmer accidentally struck by a scythe (long cutting blade) by another worker while cutting wheat was admitted to the county hospital with severe bleeding. During physical examination the doctor noted that the patient has reduced sensation over the skin of the posterior calf and lateral ankle. Which of the following nerves was injured? A. Common fibular B. Deep fibular C. Saphenous D. Sural E. Superficial fibular

D. The farm instrument has injured the deep fibular (peroneal) branch of the common fibular (pero- neal) nerve. It is vulnerable to injury as it arises from the common fibular (peroneal) at the neck of the fib- ula. The muscles denervated are largely dorsiflexors of the foot; hence, foot drop and steppage gait can occur. Sensation on the dorsum of the foot is still present; therefore, the superficial branch is mostly or entirely intact, although sensation between the first and second toes would be absent. Femoral nerve injury would re- sult in loss of knee extension. Loss of the sciatic nerve would result in loss of both the tibial and common fibular (peroneal) nerves. Because plantar flexion is still functional, the tibial nerve has not been cut.GAS 596, 597, 599, 624-627; GA 326-327, 334-335

A 58-year-old male farmer was accidentally struck with a scythe (a long, curved cutting blade) by another worker while they were cutting wheat. He was admit- ted to the county hospital with severe bleeding. During physical examination the doctor noted that the patient has foot drop, although sensation was present over the dorsum of the foot and the skin of the posterior calf. Which of the following nerves was injured? A. Femoral nerve B. Sciatic nerve C. Superficial fibular (peroneal) nerve D. Deep fibular (peroneal) nerve E. Common fibular (peroneal) nerve

D: Abductor hallucis muscle. The muscles and associated structures in the plantar aspect of the foot are organized into four layers from superficial (layer 1) to deep (layer 4). The first layer includes the abductor hallucis mus- cle as well as the abductor digiti minimi and the flexor digi- torum brevis. Choice A (Plantar arterial arch) is incorrect. The plantar arterial arch (deep plantar arch) is an anasto- motic vessel formed by the lateral plantar artery and the deep plantar branch of the dorsalis pedis artery. The lateral plantar artery portion (providing the main flow into the plantar arch) is initially located in the plane between the first and second layers of plantar muscles and then courses deeper, between the third and fourth layers. The contribution of the dorsalis pedis artery pierces between the first and second metatar- sals into the deepest plantar layer. Choice B (Tendons of the flexor digitorum longus muscle) is incorrect. These tendons are located in the second layer of plantar muscles, with the quadratus plantae and the tendon of the flexor hallucis lon- gus. The four lumbrical muscles are also found here, attached to the tendons of the flexor digitorum longus. Choice C (Tendon of the fibularis [peroneus] longus muscle) is incor- rect. This long tendon crosses the foot deep to the fourth layer of plantar muscles. Some authors include this tendon as a member of the fourth layer. Choice E (Superficial fibular [peroneal] nerve) is incorrect. The superficial fibular nerve emerges from the lateral compartment of the leg and distrib- utes its terminal cutaneous branches across the dorsum of the foot.

A 6-year-old boy playing barefooted in his backyard steps on a piece of broken glass and suffers a large transverse cut on his sole, at the level of the midfoot. In the emergency room, the examining physician determines the cut is to the depth of the first layer of the plantar muscles. Which of the following structures is most likely damaged in this injury? (A) Plantar arterial arch (B) Tendons of the flexor digitorum longus muscle (C) Tendon of the fibularis (peroneus) longus muscle (D) Abductor hallucis muscle (E) Superficial fibular (peroneal) nerve

D. Spinal tuberculosis can spread within the sheath of the psoas major to its insertion with the ilia- cus upon the lesser trochanter, presenting there also with painful symptoms. The iliopsoas muscle is the principal flexor of the hip joint. Abduction of the hips is performed by the gluteus medius and minimus with assistance from short lateral rotator muscles. Extension of the hip is a function of the gluteus maximus, to- gether with the hamstring muscles. Internal rotation is performed by the adductor muscle group. GAS 348-349, 353, 561, 562; GA 29, 42, 127, 137, 141, 173, 175-176, 254, 291

A 61-year-old female immigrant had been diag- nosed with spinal tuberculosis. The woman had devel- oped a fluctuant, red, tender bulge on one flank, with a similar bulge in the groin on the same side. This pre- sentation is likely due to spread of disease process within the fascia of a muscle with which of the follow- ing actions at the hip? A. Abduction B. Adduction C. Extension D. Flexion E. Internal rotation

C: Between the tendons of the extensor hallucis longus and extensor digitorum longus muscles. The dorsalis pedis pulse is an important indicator of peripheral vascular integrity. The dorsalis pedis artery is the direct continuation of the anterior tibial artery into the dorsum of the foot. Its pulse is normally easy to palpate, as the vessel is subcutaneous and lies against the navicular and cuneiform bones, just lateral to the tendon of the extensor hallucis longus. Because of the promi- nence of the extensor hallucis longus and extensor digitorum longus tendons, the vessel can be located between them by asking the patient to slightly dorsiflex the digits. Choice A (Immediately anterior to the medial malleolus) is incorrect. The dorsalis pedis artery begins midway between the malleoli on the dorsum of the ankle. It is not immediately related to either malleolus. Choice B (Immediately anterior to the lateral malleolus) is incorrect. The dorsalis pedis artery begins mid- way between the malleoli on the dorsum of the ankle. It is not immediately related to either malleolus. Choice D (Between the tendons of the extensor digitorum longus and fibularis [peroneus] tertius muscles) is incorrect. This location is too far lateral from the normal position of the dorsalis pedis artery. Choice E (Immediately lateral to the tendon of the fibularis [peroneus] tertius muscle) is incorrect. This location is too far lateral from the normal position of the dorsalis pedis artery

A 65-year-old man with a history of heavy smoking visits his physician complaining of intermittent pain in his feet, accompanied by pallor and coldness of his feet. The physician suspects vascular insufficiency and takes a pulse of the dorsalis pedis artery. That pulse is best palpated at which of the following locations? A) Immediately anterior to the medial malleolus (B) Immediately anterior to the lateral malleolus (C) Between the tendons of the extensor hallucis longus and extensor digitorum longus muscles (D) Between the tendons of the extensor digitorum longus and fibularis (peroneus) tertius muscles (E) Immediately lateral to the tendon of the fibularis (per- oneus) tertius muscle

E: Inferior gluteal nerve. The inferior gluteal nerve innervates the gluteus maximus. This muscle produces lateral rotation and extension of the thigh at the hip joint, especially when the thigh is in a flexed position (rising from a sitting position or climbing stairs). The gluteus maximus can be tested by placing the patient in a prone position and ask- ing them to perform a straight leg lift. During this functional test, the examiner should observe and palpate the contraction of this muscle. Choice A (Femoral nerve) is incorrect. The femoral nerve supplies the motor innervation to the anterior compartment of the thigh. In general, loss of the femoral nerve would lead to weakness in extending the knee and flex- ing the thigh. The patient was having difficulty extending the thigh at the hip joint, so the femoral nerve can be eliminated. Choice B (Obturator nerve) is incorrect. The obturator nerve supplies motor innervation to the muscles of the medial com- partment of the thigh. These muscles collectively adduct the thigh. However, the individual components also participate in additional actions: lateral (external) rotation of the thigh (obturator externus), flexion of the hip (adductor brevis; adductor magnus), and flexion and medial rotation of the leg (gracilis). However, this patient was having trouble with extension of the thigh at the hip joint, which is not a function of the obturator nerve. Choice C (Sciatic nerve) is incorrect. The sciatic nerve supplies the Biceps femoris, posterior half of the Adductor magnus, Semitendinosus, and Semimembra- nosus. The mnemonic for the muscles innervated by the sci- atic nerve is "BASS." Three of these muscles, the long head of the biceps femoris, semitendinosus, and semimembranosus, comprise the hamstrings, which (along with the short head of the biceps femoris) form the posterior compartment of the thigh. Collectively, these muscles extend the thigh at the hip joint and flex the leg at the knee joint. Though this patient is having trouble extending the thigh at the hip joint, loss of the sciatic nerve would not explain the observed weakness in external rotation of the thigh. Also, the gluteus maximus, and not the hamstrings, is the strongest muscle in extension of the thigh, and it acts primarily when force is needed, as in climbing stairs. Choice D (Superior gluteal nerve) is incor- rect. The superior gluteal nerve supplies motor innervation to the gluteus medius, gluteus minimus, and tensor fasciae latae muscles. Loss of this innervation would lead to weakness in abducting and medially rotating the thigh at the hip joint. These muscles are also responsible for keeping the pelvis level during the swing phase of gait.

A 70-year-old man reports an inability to climb stairs and stand up from a sitting position. Further examination also shows weakness when laterally rotating the thigh against resistance. What nerve is most likely compromised in this patient? (A) Femoral nerve (B) Obturator nerve (C) Sciatic nerve (D) Superior gluteal nerve (E) Inferior gluteal nerve

C. The iliofemoral ligament is the most impor- tant ligament reinforcing the joint anteriorly that would resist both hyperextension and lateral rotation at the hip joint. The pubofemoral ligament reinforces the joint inferiorly and limits extension and abduc- tion. The ischiofemoral ligament reinforces the joint posteriorly and limits extension and medial rotation. Negative pressure in the acetabular fossa has nothing to do with resisting hyperextension of the hip joint but does help resist dislocation of the head of the fe- mur. The gluteus maximus muscle extends and later- ally rotates the thigh and does not particularly resist hyperextension. GAS 534-536; GA 212, 279

A 72-year old female suffered a hip dislocation when she fell down the steps to her garage. Which of the following structures is most significant in resisting hyperextension of the hip joint? A. Pubofemoral ligament B. Ischiofemoral ligament C. Iliofemoral ligament D. Negative pressure in the acetabular fossa E. Gluteus maximus muscle

A. the femoral nerve is the nerve of the anterior compartment of the thigh; it innervates the quadriceps femoris muscle. The quadriceps femoris muscle extends the knee.

A 72-year-old male with diabetes presents to a neurologist with complaints of discomfort in his leg and difficulty walking. Neurological examination reveals weakness of extension of the leg, fixation of the knee and some wasting of the quadriceps femoris muscle. An injury of which of the following nerves most likely contributes to this patient's symptoms? A. Femoral nerve B. Obturator nerve C. Sciatic nerve D. Tibial nerve

B. The lateral circumflex femoral artery arises from the deep femoral (profunda femoris) artery of the thigh and sends a descending branch down the length of the femur to anastomose with the superior medial genicular artery and the superior lateral ge- nicular artery. The medial circumflex femoral artery is responsible for supplying blood to the head and neck of the femur, and it does not anastomose with distal vessels at the knee. The first perforating artery sends an ascending branch that anastomoses with the me- dial circumflex femoral and the inferior gluteal artery in the buttock. The inferior gluteal artery is a branch of the internal iliac; it has important anastomotic sup- ply to the hip joint. The typically small descending genicular branch of the femoral artery is given off just proximal to the continuation of the femoral artery as the popliteal.

A 72-year-old woman is admitted to the hospital with a painful right foot. A CT scan examination re- veals a thrombotic occlusion of the femoral artery in the proximal part of the adductor canal. Which artery will most likely provide blood supply to the leg through the genicular anastomosis? A. Medial circumflex femoral B. Descending branch of the lateral circumflex femoral C. First perforating branch of the deep femoral D. Inferior gluteal E. Descending genicular branch of femoral

C: Gluteus maximus. Several muscles cross the femoral neck and would react to the fracture by contracting, thus pulling the distal segment of the limb upward over the fracture and shortening the limb. The gluteus maximus inserts partly into the gluteal tuberosity of the femur, but mostly into the iliotibial tract, which attaches into the lateral condyle of the tibia. Thus, the gluteus maximus is a powerful extensor and lateral rotator of the thigh, with a notable influence on the leg. In this case, the strong gluteus maximus is responsible for the distinctive lateral rotation of the limb. Choice A (Semiten- dinosus) is incorrect. The semitendinosus muscle primarily flexes the knee and extends the hip as well as contributing to medial rotation of the leg rather than lateral rotation. Choice B (Adductor longus) is incorrect. The adductor longus muscle primarily adducts the thigh. It does not contribute to either medial or lateral rotation of the leg. Choice D (Rectus femoris) is incorrect. The rectus femoris muscle extends the leg at the knee joint and contributes to flexion at the hip joint, but it does not contribute to either medial or lateral rotation of the leg. Choice E (Gracilis) is incorrect. The gracilis muscle contributes to medial rotation of the leg rather than lateral rotation.

A 72-year-old woman slips and falls on a wet floor, fracturing the neck of her right femur. Subsequent physical examination in the ER shows her right foot is laterally rotated, and the right lower extremity appears slightly shorter than the left. Which of the following muscles is mainly responsible for the rotated posture of the right limb? (A) Semitendinosus (B) Adductor longus (C) Gluteusmaximus (D) Rectusfemoris (E) Gracilis

C. An intracapsular femoral neck fracture causes avascular necrosis of the femoral head because the fracture damages the radicular branches of the medial and lateral circumflex arteries that pass beneath the ischiofemoral ligament and pierce the femoral neck. Until an individual reaches about 6 to 10 years of age, blood supply to the head of the femur is provided by a branch of the obturator artery that runs with the liga- ment of the head of the femur. Thereafter, the artery of the ligament of the head of the femur is insignificant. Intertrochanteric fracture of the femur would not dam- age the blood supply to the head of the femur but would cause complications because the greater tro- chanter is an attachment site for several gluteal mus- cles. During childhood the obturator artery provides the artery of the ligament of the head of the femur. Thrombosis of the obturator artery could result in mus- cular symptoms, although there are several collateral sources of blood supply in the thigh. Comminuted fracture of the extracapsular femoral neck would not ordinarily imperil the vascular supply. GAS 533, 642; GA 275-276, 278

A 75-year-old man is transported to the eme gency department with severe pain of his right hip and thigh. A radiographic examination reveals avascular necrosis of the femoral head (Fig. 5-2). Which of the following conditions most likely occurred to produce avascular necrosis in this patient? A. Dislocation of the hip with tearing of the ligament of the head of the femur B. Intertrochanteric fracture of the femur C. Intracapsular femoral neck fracture D. Thrombosis of the obturator artery E. Comminuted fracture of the extracapsular femoral neck

C. The medial circumflex femoral artery is re- sponsible for supplying blood to the head and neck of the femur by a number of branches that pass under the edge of the ischiofemoral ligament. This artery is most likely at risk for injury in an extracapsular frac- ture of the femoral neck. The inferior gluteal artery arises from the internal iliac and enters the gluteal region through the greater sciatic foramen, below the piriformis. The first perforating artery sends an as- cending branch that anastomoses with the inferior gluteal artery in the buttock. The obturator artery arises from the internal iliac artery and passes through the obturator foramen. It commonly supplies the ar- tery within the ligament of the head of the femur. The superior gluteal artery arises from the internal iliac artery and enters through the greater sciatic foramen above the piriformis.

A 75-year-old woman is admitted to the hospital after falling in her bathroom. Radiographic examina- tion reveals an extracapsular fracture of the femoral neck. Which artery is most likely at risk for injury? A. Inferior gluteal B. First perforating branch of deep femoral C. Medial circumflex femoral D. Obturator E. Superior gluteal

C: Tendon of the fibularis (peroneus) longus. Several structures that enter or exit the foot do so via close positional relationships to the medial and lateral malleoli. As a result, these bony prominences serve as important landmarks for locating structures at the ankle. Also, because a horizon- tal axis through the malleoli forms the axis of rotation about which flexion and extension of the foot occur, the positions of muscle tendons relative to the malleoli determine plantar flex- ion versus dorsiflexion. The tendons of the fibularis (peroneus) longus and brevis muscles pass tightly against the posterior side of the lateral malleolus as they leave the lateral compart- ment of the leg and cross the ankle. Therefore, both muscles act to produce plantar flexion of the foot and may be injured in trauma posterior to the lateral malleolus. Choice A (Saphen- ous nerve) is incorrect. The saphenous nerve enters the medial aspect of the foot by crossing the ankle anterior to the medial malleolus, in close company with the great saphenous vein. Choice B (Tendon of the fibularis [peroneus] tertius) is incor- rect. The fibularis tertius is a member of the anterior compart- ment of the leg. Its tendon crosses the anterior aspect of the ankle, bound by the extensor retinaculum. It is the most lateral tendon from the anterior compartment but does not have a particularly close relation to the lateral malleolus. Because it does pass anterior to the malleoli, the tendon of the fibularis tertius muscle participates in dorsiflexion of the foot at the ankle joint and eversion of the foot at the subtalar and trans- verse tarsal joints. Choice D (Posterior tibial artery) is incor- rect. This vessel descends through the tibial side of the poste- rior compartment of the leg and crosses the ankle posterior to the medial malleolus before it terminates by dividing into the medial and lateral plantar arteries. Choice E (Great saphenous vein) is incorrect. The great saphenous vein originates from the medial end of the dorsal venous arch in the foot. It ascends into the leg by crossing the ankle anterior to the medial malleolus, in close company with the saphenous nerve.

A man working in a junkyard trips and falls into a pile of scrap metal, suffering a deep cut immediately posterior to the lateral malleolus. Which of the following is most likely to be injured? (A) Saphenous nerve (B) Tendon of the fibularis (peroneus) tertius (C) Tendon of the fibularis (peroneus) longus (D) Posterior tibial artery (E) Great saphenous vein

B The deep fibular nerve is a branch of the common fibular nerve; it innervates the muscles of the anterior compartment of the leg and provides cutaneous innervation to the first dorsal web space.

A patient presents with a complaint of weakness of dorsiflexion of the foot and numbness on the top of the foot. On physical exam you note diminished sensation only over the first dorsal web space. Which of the following nerves has most likely been injured? A. Tibial B. Deep fibular C. Sural D. Common fibular E. Superficial fibular

B: Profunda femoris artery. The profunda femoris artery (deep femoral artery; deep artery of the thigh) gives off the perforating arteries that supply blood to the pos- terior femoral compartment. Arising from the femoral artery, the profunda femoris artery gives off the medial and lateral circumflex femoral arteries before it descends to give off a series of (usually four in number) perforating arteries. These arteries are so named because they pierce (perforate) through the adductor magnus muscle to reach the posterior compart- ment of the thigh. The perforating arteries supply the adduc- tor magnus and hamstring muscles of the posterior compart- ment of the thigh. Choice A (Femoral artery) is incorrect. The femoral artery gives rise to the profunda femoris artery, which in turn gives off the perforating branches. Choice C (Obtura- tor artery) is incorrect. The obturator artery is a branch of the internal iliac artery within the pelvic cavity. It enters the thigh through the obturator canal and divides into anterior and posterior branches, which envelope the adductor brevis muscle. The obturator artery supplies the adductor muscles in the medial compartment of the thigh. Choice D (Popliteal artery) is incorrect. The popliteal artery is the direct continu- ation of the femoral artery in the popliteal fossa. It gives rise to five genicular arteries that form an extensive anastomotic network around the knee. Choice E (Medial femoral circum- flex artery) is incorrect. This vessel arises from the femoral or profunda femoris artery high within the femoral triangle. It supplies the muscles in the upper medial thigh and the hip joint. This important vessel is one component of the cruciate anastomosis around the hip and also provides the main supply to the head and neck of the femur.

A patient presents with extreme pain due to arterial insuffi- ciency in the posterior femoral compartment. This compart- ment of the thigh receives its blood supply mainly from the perforating arteries. An arteriogram confirms partial occlusion of the artery that gives rise to these perforating arteries. What artery is occluded in the arteriogram? (A) Femoralartery (B) Profunda femoris artery (C) Obturatorartery (D) Poplitealartery (E) Medial femoral circumflex artery

D: Lateral femoral cutaneous nerve. This case is the classic presentation of meralgia paresthetica, an entrap- ment of the lateral femoral cutaneous nerve as it passes under the inguinal ligament in proximity to the anterior superior iliac spine. Impingement of the lateral femoral cutaneous nerve causes abnormal sensations of burning, pain, and numbness in the distribution of this nerve, which is the lateral por- tion of the upper thigh. Meralgia paresthetica may be called "bikini brief syndrome" because it is seen in individuals who have gained considerable weight in a short period (e.g., in pregnancy), and the entrapment of the nerve can be caused by tight undergarments. In this case, the student's backpack rested near the anterior superior iliac spine, which led to his presentation. Choice A (Femoral branch of genitofemoral nerve) is incorrect. The femoral branch of the genitofemo- ral nerve is formed by the ventral rami of L1-2. This nerve supplies the upper medial aspects of the thigh. Due to the lateral location of the symptoms in this patient, this nerve is not involved. Choice B (Saphenous nerve) is incorrect. The saphenous nerve is a terminal sensory branch of the femoral nerve, which traverses medially through the adductor canal in the thigh to supply the medial side of the leg and foot, including the medial malleolus of the tibia. Due to the loca- tion of the sensory deficits in the upper lateral thigh, this nerve is not involved in this patient's presentation. Choice C (Anterior cutaneous branches of femoral nerve) is incorrect. The anterior cutaneous branches of the femoral nerve supply the upper medial aspect of the thigh. These nerves are derived from L2-4 and are too far medial to elicit the symptoms in this medical student. Choice E (Iliohypogastric nerve) is incor- rect. The iliohypogastric nerve arises primarily from the ven- tral ramus of L1, with possible contributions from T12. This nerve runs above the anterior superior iliac spine within the anterolateral muscular wall of the abdomen. The iliohypo- gastric nerve supplies the suprapubic region of the abdomen rather than the lateral thigh.

A rising second-year medical student spends his summer hiking the Appalachian Trial with a 100-lb backpack in tow. After a month of hiking 30-mi/day (48-km/day), he notices numb- ness, tingling, and burning sensations in the lateral aspect of his right upper thigh. His symptoms are exacerbated by his backpack pressing on the area surrounding his right anterior superior iliac spine. What nerve is most likely affected? (A) Femoral branch of genitofemoral nerve (B) Saphenous nerve (C) Anterior cutaneous branches of femoral nerve (D) Lateral femoral cutaneous nerve (E) Iliohypogastric nerve

B: Tendon of the flexor hallucis longus (FHL) muscle. The sustentaculum tali is a bony ledge project- ing off the medial side of the calcaneus, as seen in the given drawing. It supports the head of the talus and serves as a pulley-like device for the tendon of the FHL. This tendon emerges from the posterior deep compartment of the leg and turns through a groove on the inferior side of the sustentacu- lum tali to align itself with the hallux. Thus, the FHL uses the sustentaculum tali to change its direction and improve its mechanical efficiency. Likewise, the obturator internus ten- don uses the lesser sciatic notch as a pulley to change its line of action. Because of their intimate relationship, a fracture of the sustentaculum tali immediately endangers the FHL ten- don. Choice A (Tendon of the tibialis posterior muscle) is incorrect. This tendon accompanies the tendon of the FHL out of the posterior deep compartment of the leg. However, the tibialis posterior tendon crosses the medial side of the ankle by hugging the posterior side of the medial malleo- lus to reach the medial aspect of the foot. Thus, the tibialis posterior also utilizes a bony prominence as a pulley to alter its line of action. Choice C (Tendons of the flexor digitorum brevis muscle) is incorrect. The flexor digitorum brevis muscle is located in the first muscle layer in the plantar side of the foot and is not related to the sustentaculum tali. However, the flexor digitorum longus is the third member of the posterior deep compartment of the leg. Its tendon does cross the medial side of the ankle in close company with the FHL and tibi- alis posterior. Choice D (Small saphenous vein) is incorrect. This important cutaneous vein arises from the lateral end of the dorsal venous arch of the foot. It ascends into the leg by crossing the ankle posterior to the lateral malleolus. It is at this location that the small saphenous vein is often harvested for vein grafting procedures. Choice E (Plantar arterial arch) is incorrect. The plantar arterial arch is located deep in the plantar aspect of the foot, crossing the metatarsals. It is formed from the lateral plantar artery and the deep plantar artery (a branch of the dorsalis pedis artery).

A roofing installer falls off a high ladder and lands with the sole of his right foot hitting the ground first. He suffers a fracture and inferior displacement of the sustentaculum tali of the calcaneus. Which of the following structures is most likely torn? (A) Tendon of the tibialis posterior muscle (B) Tendon of the flexor hallucis longus (FHL) muscle (C) Tendons of the flexor digitorum brevis muscle (D) Small saphenous vein (E) Plantar arterial arch

E: Plantar calcaneonavicular (spring) ligament. The condition of "flat-foot" (pes planus; talipes planus; "fallen arch") is that in which the medial longitudinal arch of the foot significantly lowers or collapses altogether. This collapse may cause pain due to stretching of the plantar muscles and ligaments, and eversion and abduction of the forefoot lead- ing to excessive wear on the medial side of the soles of shoes. The medial longitudinal arch of the foot is higher and more mechanically significant than the lateral longitudinal arch. It runs through the talus, calcaneus, navicular, cuneiforms, and the three medial metatarsal bones. It is supported largely by the plantar calcaneonavicular (spring) ligament and the ten- don of the flexor hallucis longus muscle. Thus, collapse of this arch is likely to put significant strain on the spring ligament. Choice A (Calcaneal [Achilles] tendon) is incorrect. The calca- neal tendon (tendo calcaneus; Achilles tendon) is the tendon of insertion for the gastrocnemius and soleus muscles onto the tuberosity of the calcaneus (posterior aspect of the heel). It does not enter the sole of the foot and does not provide support to the arches of the foot. Choice B (Plantar calcaneo- cuboid [long plantar] ligament) is incorrect. The plantar calca- neocuboid ligament is located in the sole of the foot, running from the plantar side of the calcaneus forward to the cuboid and lateral metatarsals. That is, it underlies and supports the lateral longitudinal arch of the foot. The plantar calcaneo- cuboid (long plantar) ligament may be strained somewhat in fully pronounced flat foot. However, that would normally be secondary to strain of the plantar calcaneonavicular (spring) ligament. Choice C (Extensor retinaculum) is incorrect. The extensor retinaculum is a two-part (superior and inferior) band of deep fascia across the anteroinferior leg and dor- sum of the foot. It is important in binding and stabilizing the extensor tendons that emerge from the anterior compartment of the leg to pass into the dorsum of the foot. Choice D (Ten- don of the fibularis [peroneus] longus muscle) is incorrect. This very long tendon enters the deep lateral plantar aspect of the foot and runs across the foot to attach onto the base of the first metatarsal and medial cuneiform. Due to its course, the tendon supports the lateral longitudinal arch of the foot and enables the muscle to participate in eversion and plantar flexion of the foot at the ankle joint.

A veteran infantry soldier develops painful flat feet after several years of service including hundreds of miles of marches. The pain is particularly acute on the medial aspect of his sole. Which of the following structures is most likely strained in this condition? (A) Calcaneal (Achilles) tendon (B) Plantar calcaneocuboid (long plantar) ligament (C) Extensorretinaculum (D) Tendon of the fibularis (peroneus) longus muscle (E) Plantar calcaneonavicular (spring) ligament

B: anterior talofibular The anterior talofibular ligament is a component of the lateral ligament complex on the lateral aspect of the ankle.

A. posterior talofibular B. anterior talofibular C. deltoid D. calcaneofibular E. anterior talofibular

A. Posteriorly

A. posteriorly B. anteriorly C. laterally D. Medially

B: L4

A: L2 B: L4 C: S1 D: S2

D. The piriformis muscle arises from the pelvic surface of the sacrum, passes through the greater sci- atic notch, and inserts at the greater trochanter. It is considered the "key" to gluteal anatomy; the greater sciatic foramen is the "door." The gluteus medius lies posterior to the piriformis. The sciatic nerve emerges from the greater sciatic foramen, through the infra- piriformic space. The spine of the ischium separates the greater and lesser sciatic foramina.

After dividing the overlying superficial tissues and gluteal musculature in a 68-year-old female patient, the orthopedic surgeon carefully identified the underlying structures. The key landmark in the gluteal region, relied upon in explorations of this area, is provided by which of the following structures? A. Gluteus medius B. Obturator internus tendon C. Sciatic nerve D. Piriformis muscle E. Spine of the ischium

C: Femoral hernia. The femoral ring is a weak- ened aspect in the anterior abdominal wall through which a femoral hernia enters the femoral canal. This type of hernia often contains abdominal viscera and is more common in females due to their wider pelves. Femoral herniae are also more susceptible to strangulation, in which case the blood supply can be interrupted due to the sharp boundaries of the femoral ring, particularly the lacunar ligament. Strangulation can lead to ischemia, sharp pain, and necrosis of the impinged tissue. Because this patient is female and the sudden onset of her symptoms following strenuous lifting, strangulation of a femoral hernia is the most likely diagnosis. Her nausea and vomiting may be due to a small bowel obstruction or may be a result of the severe pain due to the ischemia associated with the hernia. The location of the globular mass may be dif- ficult to distinguish from indirect or direct inguinal herniae. However, several studies suggest CT imaging can differenti- ate between these hernia types. Direct inguinal herniae rarely occur in females. Males are three to four times more likely to have an indirect inguinal hernia, due to the embryologi- cal descent of the testes. Choice A (Indirect inguinal hernia) is incorrect. An indirect inguinal hernia is usually a congeni- tal hernia that results when abdominal cavity contents her- niate through a patent processus vaginalis, or in an adult, the inguinal canal. The hernia passes through the deep and superficial inguinal rings and descends into the scrotum in males. Indirect inguinal herniae are three to four times more common in men and do not usually evoke the high incidence of strangulation seen in femoral herniae. Choice B (Direct inguinal hernia) is incorrect. A direct inguinal hernia is an acquired hernia that results when abdominal cavity contents herniate through a weakness in the anterior abdominal wall in the inguinal (Hesselbach) triangle. The hernia exits through the superficial inguinal ring but does not usually descend into the scrotum. Direct inguinal herniae are rare in women. In fact, some references cite groin herniae as 25 times more likely to occur in men. Choice D (Lymphadenitis of superficial inguinal nodes) is incorrect. Lymphadenitis (swollen lymph nodes) of the superficial inguinal nodes could be responsible for the globular mass detected in this patient. However, the history of this patient does not include a recent bacterial or viral infection, which would cause these lymph nodes to be tender and swollen. Lymph nodes affected by cancer could also appear as a globular mass. However, when affected by cancer, these nodes are enlarged but usually not painful. Most importantly, the pain in this patient is acute, which would rule out lymph node involvement, especially due to the patient's history of onset after heavy lifting. Choice E (Fractured hip) is incorrect. No trauma was reported by the patient, so a frac- tured hip can be easily eliminated as a choice, especially due to the location of the globular mass inferolateral to the pubic tubercle.

After spending 2 days moving heavy furniture out of her house, a 56-year-old woman goes to an emergency room in acute pain. The patient reports nausea, vomiting, and severe abdominal pain. On examination, the doctor discovers a painful, globular mass located inferior and lateral to the pubic tubercle. Given her presentation and history, what is the most likely diagnosis? (A) Indirect inguinal hernia (B) Direct inguinal hernia (C) Femoralhernia (D) Lymphadenitis of superficial inguinal nodes (E) Fractured hip

C. The obturator artery provides the artery within the ligament of the head of the femur (in about 60%), the artery that supplies the head of the femur, primarily during childhood, later becoming atretic. In the adult this artery supplies only the area of the fovea of the head of the femur. The ligament of the head of the fe- mur arises from the acetabular notch, thereafter receiv- ing the little artery. In some individuals the medial circumflex femoral gives origin to the artery of the head. In the adult the arterial supply of the neck and head is provided by intracapsular branches of the me- dial circumflex femoral and lateral circumflex femoral arteries that pierce the neck of the femur, with some supply also from the gluteal arteries. The lateral cir- cumflex femoral artery arises from the deep femoral and supplies the vastus lateralis. The pudendal artery arises from the internal iliac and provides blood supply for the structures of the perineum. Quite often, when an older patient with osteoporosis has a hip fracture, the femoral neck may have broken, precipitating a fall, rather than the fall resulting in the hip fracture. GAS 473, 474-477, 540, 541, 573; GA 220, 232, 234, 237, 250, 277, 279, 292

An 82-year-old grandmother slipped on the polished floor in her front hall and was transported to the emergency department and admitted for examination with a complaint of great pain in her right lower limb. During physical examination it is observed by the resident that the right lower limb is laterally rotated and noticeably shorter than her left limb. Radiographic examination reveals an intracapsular fracture of the fem- oral neck. Which of the following arteries supplies the head of the femur in early childhood but no longer in a patient of this age? A. Superior gluteal B. Lateral circumflex femoral C. A branch of the obturator artery D. Inferior gluteal E. Internal pudendal

C: Vastus medialis. The vastus medialis muscle, a component of the quadriceps femoris, inserts into the patella and the tibial tuberosity through the common quadriceps ten- don and patellar ligament. This muscle helps extend the leg at the knee joint, but it also maintains a medial pull on the patella, reducing the lateral, dislocating force. The patella is stabilized by the vastus medialis muscle and the prominent femoral con- dyles, which usually prevent lateral dislocation during flexing of the leg at the knee joint. Moreover, the vastus medialis muscle helps stabilize the patella within the patellar groove to control the tracking of the patella when the knee is bent and straightened. Females are at a greater risk of dislocating the patella due to the width of their hips, which tends to cause genu valgum ("knocked-knee" appearance). In this patient, her conditioning was suspect, so strengthening the quadriceps femoris muscle, especially the vastus medialis, should stabilize the patella, hold it within the patellar groove, and decrease the incidence of future patellar dislocations. Choice A (Vastus intermedius) is incorrect. The vastus intermedius muscle, the central deep component of the quadriceps femoris, inserts into the patella and the tibial tuberosity through the common quadriceps tendon and patellar ligament. This muscle helps extend the leg at the knee joint. Due to its insertion into the superior aspect of the patella, this muscle does not provide a medial pull on the patella, so targeting this muscle specifically in rehabilitation would not prevent lateral dislocation of the patella. However, strengthening the entire quadriceps femo- ris muscle would help keep the patella in the patellar groove. Choice B (Vastus lateralis) is incorrect. The vastus lateralis muscle (lateral head of the quadriceps femoris) inserts into the patella and the tibial tuberosity through the common quadri- ceps tendon and patellar ligament. This muscle helps extend the leg at the knee joint. Due to its insertion into the lateral aspect of the patella, the orientation of its muscle fibers will not prevent lateral dislocation of the patella. Choice D (Rec- tus femoris) is incorrect. The rectus femoris muscle (anterior [superficial] head of the quadriceps femoris) inserts into the patella and the tibial tuberosity through the common quadri- ceps tendon and patellar ligament. This muscle helps extend the leg at the knee joint and also flexes the thigh at the hip joint because it is the only component of the quadriceps femoris to cross the hip joint. Due to its insertion into the superior aspect of the patella, this muscle does not provide a medial pull on the patella, so targeting this muscle specifi- cally in rehabilitation would not prevent lateral dislocation of the patella. However, strengthening the entire quadriceps femoris muscle would help keep the patella in the patellar groove. Choice E (Tibialis anterior) is incorrect. The tibialis anterior muscle does not insert into the patella, so targeting this muscle during physical therapy and rehabilitation would not prevent future dislocations of the patella.

An overweight woman participates in her first rugby match with- out proper training and conditioning. Upon catching the open- ing kickoff, she awkwardly twists her right knee, screams in pain, and falls to the ground. The team manager notes her patella is dislocated, residing on the lateral side of her knee. After straightening the woman's knee, the patellar dislocation is reduced (goes back into place). To prevent future dislocation of the patella, what specific muscle should be targeted during rehabilitation? (A) Vastusintermedius (B) Vastus lateralis (C) Vastusmedialis (D) Rectusfemoris (E) Tibialis anterior

E. The popliteal artery is the continuation of the femoral artery after it passes through the hiatus of the adductor magnus. The popliteal artery divides into the anterior and posterior tibial arteries. The anterior tibial artery passes between the tibia and fibula prox- imally in the posterior compartment of the leg, whereas the posterior tibial artery continues in the posterior compartment of the leg, to its division into medial and lateral plantar arteries. The posterior tibial artery provides origin for the fibular (peroneal) artery, which supplies the lateral compartment of the leg. The deep femoral artery provides origin for the three or four perforating branches that supply the posterior compartment of the thigh.

Arteriography of an 82-year-old female reveals a possible cause for her limb pain during her workout routines in the health spa. The artery that was oc- cluded is one that should have been demonstrable passing between the proximal part of the space be- tween the tibia and fibula. Which of the following ar- teries is most likely affected? A. Deep femoral B. Popliteal C. Posterior tibial D. Fibular (peroneal) E. Anterior tibial

E: Lateral plantar nerve. The lateral plantar nerve, which is homologous to the ulnar nerve in the hand, innervates all of the intrinsic foot muscles, with the exception of the four muscles supplied by the medial plantar nerve. The lateral plantar nerve innervates the dorsal interossei of the foot and the abductor digiti minimi muscles, which are responsible for abduction of the lateral four toes. Choice A (Sural nerve) is incorrect. The sural nerve is a cutaneous nerve, so it would not be responsible for abduction of the lateral four toes. The course of this nerve parallels the small saphenous vein, and damage to the sural nerve would lead to numbness and paresthesia in the dorsal aspect of the lateral fifth toe and lateral malleolus of the fibula. No motor deficits would be seen. Choice B (Deep fibular nerve) is incorrect. The deep fibular (peroneal) nerve supplies motor innervation to the four muscles of the anterior compartment of the leg and two intrinsic muscles of the foot: extensor digitorum brevis and extensor hallucis brevis. Nei- ther of these two foot muscles is involved with abduction of the toes. Choice C (Superficial fibular nerve) is incorrect. The superficial fibular nerve supplies motor innervation to the two muscles (fibularis longus and brevis) of the lateral compart- ment of the leg and cutaneous (sensory) innervation to the distal third of the anterior surface of the leg and dorsum of the foot. These muscles are primarily responsible for eversion of the foot at the ankle joint and are not responsible for any toe movements. Choice D (Medial plantar nerve) is incorrect. The medial plantar nerve, which is homologous to the median nerve in the hand, innervates four intrinsic foot muscles: first Lumbrical, Abductor hallucis, Flexor digitorum brevis, and Flexor hallucis brevis. The mnemonic for muscles supplied by the medial plantar nerve is the "LAFF" muscles. Though it would be responsible for abduction of the first toe, the medial plantar nerve is not responsible for abduction of the lateral four toes, which are being tested in this patient.

As part of a physical examination to evaluate lower limb function, a physician asks a patient to abduct her second through fifth toes. What specific nerve is the doctor testing? (A) Suralnerve (B) Deep fibular nerve (C) Superficialfibularnerve (D) Medial plantar nerve (E) Lateral plantar nerve

A: Adductor magnus. Hybrid muscles have two distinct parts, each supplied by a different peripheral nerve, reflecting the complex development of the muscle. The two hybrid muscles in the lower limb are the adductor magnus and the biceps femoris, both located in the thigh. The adductor magnus is composed of an adductor portion (supplied by the obturator nerve that controls the adductor muscles in the medial femoral compartment) and a hamstring portion (innervated by the tibial nerve that supplies most of the hamstring muscles in the posterior femoral compartment). The biceps femoris is composed of a larger hamstring (long head) portion (supplied by the tibial nerve) and a smaller glu- teal (short head) portion (supplied by the common fibular [peroneal] nerve). The pectineus may or may not be consid- ered a hybrid muscle. It is normally entirely supplied by the femoral nerve. However, it may be innervated by the obtura- tor nerve, and sometimes may be supplied by both the femoral and obturator nerves. Choice B (Gastrocnemius) is incorrect. Despite having two heads arising from the femur, the muscle is part of the posterior superficial compartment of the leg and is supplied entirely by the tibial nerve. Choice C (Rectus femoris) is incorrect. This muscle is a member of the anterior femoral compartment and is supplied entirely by the femoral nerve. Choice D (Semimembranosus) is incorrect. This ham- string muscle is a component of the posterior femoral com- partment, along with the biceps femoris and semitendinosus. It is controlled by the tibial nerve. Remember that the sciatic nerve is actually a bundling of the tibial and common fibular (peroneal) nerves. Do not be confused by more generalized references that ascribe the innervation of the hamstrings to the sciatic nerve versus more specific references (such as here) that differentiate the tibial and common fibular components of the sciatic nerve. Choice E (Tibialis anterior) is incorrect. This muscle is located in the anterior compartment of the leg. It is supplied entirely by the deep fibular (deep peroneal) nerve.

Due to torsionning of the lower limb and merging of separate premuscle masses during development, certain adult lower limb muscles are supplied by two separate nerves. These interneural fusions are termed "hybrid muscles". Which of the following is a hybrid muscle? (A) Adductormagnus (B) Gastrocnemius (C) Rectusfemoris (D) Semimembranosus (E) Tibialis anterior

B. This type of injury can result in the "unhappy triad" (of O'Donahue) injury, with damage to the me- dial collateral ligament (MCL), anterior cruciate liga- ment (ACL), and medial meniscus. A blow to the lateral side of the knee stretches and tears the MCL, which is attached to the medial meniscus. The ACL is tensed during knee extension and can tear subse- quent to the rupture of the MCL. The remaining an- swer choices describe structures on the lateral surface of the knee, which are not usually injured by this type of trauma.

During a football game a 21-year-old wide re- ceiver was illegally blocked by a linebacker, who threw himself against the posterolateral aspect of the runner's left knee. As he lay on the ground, the wide receiver grasped his knee in obvious pain. Which of the follow- ing structures is frequently subject to injury from this type of force against the knee? A. Fibular collateral ligament B. Anterior cruciate ligament C. Lateral meniscus and posterior cruciate ligament D. Fibular collateral and posterior cruciate ligament E. All the ligaments of the knee will be affected.

B. The medial branch of the deep fibular (pero- neal) nerve accompanies the dorsalis pedis artery and innervates the skin between the contiguous sides of the first and second toes. The saphenous nerve is re- sponsible for cutaneous innervation of the anterome- dial aspect of the leg and foot. The superficial fibular (peroneal) nerve innervates most of the dorsum of the foot, with the exception of the area where sensation was lost (medial branch of deep fibular nerve). The common fibular (peroneal) nerve gives off a cutane- ous branch, the sural nerve, which innervates the lateral aspect of the leg and lateral side of the foot.

During the preparation of an evening meal a fe- male medical student dropped a sharp, slender kitchen knife. The blade pierced the first web space of her foot, resulting in numbness along adjacent sides of the first and second toes. Which nerve was most likely injured? A. Saphenous B. Deep fibular (peroneal) C. Superficial fibular (peroneal) D. Sural E. Common fibular (peroneal)

E. The posterior cruciate ligament is responsible for preventing the forward sliding of the femur on the tibia. The anterior cruciate ligament prevents poste- rior displacement of the femur on the tibia. The lat- eral collateral ligament limits extension and adduc- tion of the leg. The medial meniscus acts as a shock absorber and cushions the articular surfaces of the knee joint.

Following an injury suffered in a soccer match, a 32-year-old female is examined in a seated position in the orthopedic clinic. Holding the right tibia with both hands, the clinician can press the tibia backward under the distal part of her femur. The left tibia cannot be displaced in this way. Which structure was most likely damaged in the right knee? A. Anterior cruciate ligament B. Lateral collateral ligament C. Medial collateral ligament D. Medial meniscus E. Posterior cruciate ligament

B: Deep fibular nerve. The deep fibular nerve supplies motor innervation to the anterior compartment of the leg and sensory innervation to the space between the first and second toes. The muscles within this compartment are responsible for dorsiflexion of the ankle. This patient is suf- fering from anterior leg compartment syndrome. The signs and symptoms of anterior leg compartment syndrome can be remembered by the following mnemonic: the five "P's," which are Pain, Pallor (white appearance due to lack of blood sup- ply), Paresthesia (abnormal sensations), Paralysis, and Pulse- lessness. Anterior compartment syndrome of the leg is caused by increased intracompartmental pressure due to bleeding from the trauma or the improper casting of the lower leg. If this intracompartmental pressure is not relieved, the venous outflow will be obstructed, which will exacerbate the symp- toms. The resulting ischemia leads to previously mentioned symptoms and necrosis of the muscles and the deep fibular nerve, which supplies the anterior compartment of the leg. Severe anterior compartment syndrome is corrected surgically by incising the strong, nonyielding crural fascia to relieve the pressure. Choice A (Tibial nerve) is incorrect. The tibial nerve supplies the posterior muscles of the knee joint and leg, so it would be responsible for plantar flexion of the foot at the ankle joint, not dorsiflexion, which is affected in this patient. Choice C (Superficial fibular nerve) is incorrect. The super- ficial fibular nerve is a terminal branch of the common fibu- lar nerve that supplies motor innervation to the two muscles (fibularis longus and brevis) of the lateral compartment of the leg and cutaneous (sensory) innervation to the distal third of the anterior surface of the leg and dorsum of foot. These muscles are primarily responsible for eversion of the foot at the ankle joint; however, dorsiflexion of the foot is affected in this patient. Choice D (Medial plantar nerve) is incorrect. The tibial nerve divides into the medial and lateral plantar nerves to innervate muscles of the sole of the foot. The medial plantar nerve, which is homologous to the median nerve in the hand, innervates only intrinsic foot muscles. Because this nerve does not supply muscles that cross the ankle joint, it cannot be responsible for weakness in dorsiflexion at the ankle joint. Choice E (Lateral plantar nerve) is incorrect. The tibial nerve divides into the medial and lateral plantar nerves to innervate muscles of the sole of the foot. The lateral plantar nerve, which is homologous to the ulnar nerve in the hand, inner- vates most of the intrinsic foot muscles. Because this nerve does not supply muscles that cross the ankle joint, it cannot be responsible for weakness in dorsiflexion at the ankle joint.

Following surgery to repair a broken right tibia, a 22-year-old patient is placed in a short leg cast. Several hours later, she complains of extreme pain, numbness with a "pins and needles sensation," inflammation, and abnormal pressure on the anterior and lateral aspects of the affected lower leg. The cast is removed, and the physician notes weakness in dorsiflexion of the foot and toes, a weak dorsalis pedis arterial pulse, and sensory loss between the first and second toes. What nerve is most likely damaged? (A) Tibialnerve (B) Deep fibular nerve (C) Superficialfibularnerve (D) Medial plantar nerve (E) Lateral plantar nerve

D: Fibularis tertius. The fibularis (peroneus) tertius muscle arises off the distal portion of the extensor digitorum longus muscle and attaches to the dorsal sur- face of the base of the fifth metatarsal. This muscle is rarely found in other primates and is functionally linked to efficient terrestrial bipedalism. Though this muscle may be highly vari- able in human specimens, it is important in eversion of the foot during ambulation and may have a proprioceptive role to guard against excessive inversion of the foot at the ankle joint. Choice A (Extensor digitorum longus) is incorrect. The extensor digitorum longus arises off the superiolateral aspect of the tibia and interosseous membrane and inserts into the middle and distal phalanges of the lateral four dig- its. This muscle extends the lateral four digits and dorsiflexes the ankle. It does not insert into the base of the fifth meta- tarsal or assist in eversion. It does give rise to the fibularis tertius muscle distally. Choice B (Extensor digitorum brevis) is incorrect. The extensor digitorum brevis is an intrinsic foot muscle that inserts into the middle phalanges of the lateral four digits to extend these toes. It does not insert into the base of the fifth metatarsal or assist in eversion. Choice C (Fibularis longus) is incorrect. The fibularis longus muscle arises off the proximal aspect of the fibula and inserts into the base of the first metatarsal and medial cuneiform bone. This muscle is important in eversion of the foot; however, it can be eliminated due to its medial insertion in the foot. Choice E (Flexor digiti minimi brevis) is incorrect. The flexor digiti minimi brevis arises from the base of the fifth metatarsal and inserts into the base of the proximal phalanx of the fifth digit. It does not participate in eversion of the foot, so this answer can be easily eliminated.

Human feet are everted so that their soles lie fully on the ground during ambulation. What muscle is developmentally unique to humans, inserts into the base of the fifth metatarsal, and assists in eversion (or pronation)? (A) Extensor digitorum longus (B) Extensor digitorum brevis (C) Fibularis longus (D) Fibularis tertius (E) Flexor digiti minimi brevis

A. The Achilles tendon inserts upon the calca- neus bone. This tendon represents a combination of the tendons of gastrocnemius and soleus muscles. The tendon of the plantaris can insert with this tendon. GAS 589, 590, 602; GA 5

In an accident during cleanup of an old residen- tial area of the city, the Achilles tendon of a 32-year-old worker was cut through by the blade of a brush cutter. The patient is admitted to the hospital and a laceration of the Achilles tendon is diagnosed. Which of the fol- lowing bones serves as an insertion for the Achilles tendon? A. Calcaneus B. Fibula C. Cuboid D. Talus E. Navicular

A. femur The patella articulates with only the femur.

In the knee the patella articulates with the: A. femur B. tibia C. fibula D. Both femur and tibia E. Femur, tibia and fibular

D. lateral movement of the tibia in relation to the femur The ACL prevents anterior movement of the tibia in relation to the femur. This can be tested trying to pull the tibia forwards as if opening a drawer. The ACL should prevent the tibia from moving forward but a torn ACL will result in a "positive drawer test" meaning that the tibia will move forwards when you pull on it.

The anterior cruciate ligament prevents: A. anterior movement of the tibia in relation to the femur (hyperextension) B. posterior movement of the tibia in relation to the femur (hyperflexion) C. medial movement of the tibia in relation to the femur D. lateral movement of the tibia in relation to the femur

B. The apex of the femoral triangle occurs at the junction of the adductor longus and sartorius muscles. The subsartorial (Hunter) canal begins at this location. Immediately deep to this anatomic point lie the femoral artery, femoral vein, deep femoral artery, and deep femoral vein, often overlying one another in that se- quence. This has historically been a site of injuries with a meat cleaver. For this reason, injuries at this location are referred to as the "butcher's block" injury. Fatal loss of blood can occur in just a few minutes if pressure, or a tourniquet, is not applied immediately. The common iliac artery becomes the femoral artery at the inguinal ligament. The saphenous vein joins the femoral vein at the saphenous hiatus, or fossa ovalis. The medial circumflex femoral usually arises from the deep femoral artery about 3 to 5 inches inferior to the inguinal ligament, near the origin of the deep femoral artery from the common femoral. Serious blood loss can occur with injury to any of these vessels, although injury to them is not so often fatal.

The news reported that the 58-year-old ambassador received a slashing wound to the upper medial thigh and died from exsanguination in less than 2 minutes. What was the most likely nature of his injury? A. The femoral artery was cut at the inguinal ligament. B. A vessel or vessels were injured at the apex of the femoral triangle. C. The femoral vein was transected at its junction with the saphenous vein. D. The medial circumflex femoral was severed at its origin. E. The deep femoral artery was divided at its origin.

C the dorsalis pedis artery is a the continuation of the anterior tibial artery in the dorsum of the foot; its pulse is palpated distal to the inferior extensor retinaculum, lateral to the extensor hallucis longus tendon

The pulse of the dorsalis pedis artery is best felt in which of the following locations? A. Between the tibialis anterior and extensor hallucis longus muscles B. Distal to the inferior extensor retinaculum, medial to the tibialis anterior tendon C. Distal to the inferior extensor retinaculum, lateral to the extensor hallucis longus tendon D. Proximal to the medial malleolus and medial to the tibialis anterior tendon E. Immediately proximal to the flexor retinaculum

B: lateral...deep. The upper and lower limbs rotate in opposite directions during the 7th week of develop- ment. The upper limb rotates 90 degrees laterally, resulting in digit no. 1 (the thumb; pollux) lying on the lateral side of the hand. The lower limb rotates 90 degrees medially, result- ing in digit no. 1 (the big toe; hallux) lying on the medial side of the foot. At the base of the femoral triangle, where the large vessels enter the lower limb proper from the pelvis, the femoral artery resides lateral to the femoral vein. As the ves- sels descend through the thigh, they rotate positions relative to each other in the same way the entire limb rotated dur- ing development (i.e., 90 degrees medially). Thus, when they reach the popliteal fossa the vessels are essentially stacked on top of one another, with the popliteal artery lying ante- rior (deep) to the popliteal vein. In mentally reconstructing anatomical directions here, it is important to remember that the vessels are located on the anterior aspect of the thigh in the femoral triangle, but on the posterior aspect of the limb in the popliteal fossa. Choice A (medial...posterior) is incor- rect. The femoral artery resides lateral to the femoral vein and the popliteal artery lies anterior (=deep) to the popliteal vein. In this question, remember that recognizing either position as incorrect immediately renders the entire choice incorrect. Choice C (lateral...posterior) is incorrect. While the femo- ral artery does reside lateral to the femoral vein, the popliteal artery lies anterior (deep) to the popliteal vein. Remember the direction of rotation of the lower limb. Choice D (medial... superficial) is incorrect. Both positions are incorrect here. The femoral artery is lateral to the femoral vein and the popliteal artery is deep to the popliteal vein. Choice E (anterior...lat- eral) is incorrect. In this choice, the correct positions of the femoral and popliteal arteries are reversed. The femoral artery is lateral to the femoral vein, whereas the popliteal artery is anterior (deep) to the popliteal vein.

The relative positions of blood vessels can sometimes be explained in terms of rotation of the limbs during development. For example, upon entering the femoral triangle the femoral artery resides ____ to the femoral vein, whereas in the popliteal fossa the popliteal artery lies ____ to the popliteal vein. (A) medial...posterior (B) lateral...deep (C) lateral...posterior (D) medial...superficial (E) anterior...lateral

D. The tibialis posterior tendon is the most an- terior of the structures that pass under the laciniate ligament (flexor retinaculum) on the medial side of the ankle to enter the sole of the foot. Increases of pressure within the tissues of the plantar aspect of the foot, usually due to increased fluid from hemorrhage, inflammatory processes, or infections, cause tarsal tunnel syndrome, comparable to carpal tunnel syn- drome of the hand. The plantar aponeurosis and other fibrous and osseous tissues of the plantar sur- face cause this area to be relatively nondistensible; therefore, it takes little increase of fluid content to result in pressures adequate to restrict venous drain- age and, thereafter, arterial inflow to the region. Fas- ciotomy of the medial skin and fascia of the foot and the posterior compartment of the leg can be required to reduce the pressure and allow healing to take place. The structures that pass beneath the flexor retinaculum are, from anterior to posterior: Tendon of tibialis posterior; tendon of flexor Digitorum longus; posterior tibial Vessels and Nerve; tendon of flexor Hallucis longus. (This is the basis of the mnemonic device: "Tom, Dick, and a Very Nervous Harry.") Nei- ther the plantaris tendon nor the tibialis anterior ten- don pass through this canal. GAS 589-593, 612; GA 331-332

The swollen and painful left foot of a 23-year-old female long-distance runner is examined in the university orthopedic clinic. She states that she stepped on an unseen sharp object while running through the park several days earlier. Emergent surgery is ordered to deal with her tarsal tunnel syndrome. The tarsal tunnel is occupied normally by tendons, vessels, and nerves that pass be- neath a very strong band of tissue (the laciniate ligament) on the medial side of the ankle. What is the most anterior of the structures that pass through this tunnel? A. Flexor hallucis longus tendon B. Plantaris tendon C. Tibialis anterior tendon D. Tibialis posterior tendon E. Tibial nerve

A. The superior gluteal nerve innervates the glu- teus medius, gluteus minimus, and tensor fasciae latae muscles. The tensor fasciae latae arises from the iliac crest, inserts into the iliotibial tract of the lateral aspect of the thigh, and assists in flexion of the hip. The rectus femoris is innervated by the femoral nerve; it flexes the hip and extends the knee, thus acting upon two major joints. It arises in part from the anterior inferior iliac spine and the rim of the acetabulum and inserts into the quadriceps tendon. The gluteus maximus is sup- plied by the inferior gluteal nerve. The piriformis and quadratus femoris are both short lateral rotators of the hip and are supplied by branches of the sacral plexus. GAS 463, 466, 523, 524, 538, 539, 551-552; GA 238- 240, 251, 282-283, 295

Three years following a 62-year-old's hip replace- ment, the man's CAT scans indicated that two of his larger hip muscles had been replaced by adipose tissue. The opinion is offered that his superior gluteal nerve could have been injured during the replacement procedure, and the muscles supplied by that nerve had atrophied and been replaced by fat. Which of the following muscles receives its innervation from the superior gluteal nerve? A. Tensor fasciae latae B. Rectus femoris C. Gluteus maximus D. Piriformis E. Quadratus femoris

A. iliofemoral ligament. In this situation, the hip is pushed into hyperextension with forces directed to pro- duce anterior dislocation of the head of the femur. Thus, the ligament best positioned to resist this force crosses the ante- rior aspect of the hip joint. The iliofemoral ligament is a large, Y-shaped structure that crosses the front of the hip from the anterior inferior iliac spine and acetabular rim down to the intertrochanteric line of the femur. It is the largest ligament that reinforces the front of the hip joint, and resists hyperex- tension by tightening the head of the femur into the acetabu- lum. Choice B (Pubofemoral ligament) is incorrect. This liga- ment reinforces the hip joint capsule inferiorly and anteriorly as it runs from the pubic part of the acetabular rim to the neck of the femur. Its primary function is to resist hyperabduction of the hip. Choice C (Ischiofemoral ligament) is incorrect. The ischiofemoral ligament is a relatively weak structure that reinforces the posterior aspect of the hip joint. It attaches from the ischial portion of the acetabular rim to the neck of the femur medial to the base of the greater trochanter. Thus, its primary role is to resist medial rotation of the thigh plus aiding in resisting extension. Choice D (Lacunar ligament) is incorrect. The lacunar ligament is a reflection of fibers from the inguinal ligament down to the pubic tubercle. It forms part of the floor of the inguinal canal and the medial wall of the femoral ring (canal). While it is a notable structure in differentiating femoral from inguinal herniae, it is not part of the hip joint. Choice E (Ligament of the head of the femur) is incorrect. This ligament (also called the round ligament of the head of the femur or ligamentum teres capitis femoris) is a relatively weak structure that runs from the floor of the acetabular fossa to the small fovea in the head of the femur. It has little importance in strengthening the hip joint. However, this ligament is notable because in early life it usually carries the small nutrient artery supplying the epiphysis of the head of the femur.

Two 11 year old boys sneak up on their friend from behind. In surprising their friend, they shove him suddenly, which forcefully pushes his hips forward while he is standing relaxed talking to other friends. Which of the following ligaments best resists anterior dislocation of the head of the femur? (A) Iliofemoral ligament (B) Pubofemoral ligament (C) Ischiofemoralligament (D) Lacunarligament (E) Ligament of the head of the femuron

B. The common fibular (peroneal) nerve winds around the neck of the fibula before dividing into superficial and deep branches that go on to innervate the lateral and anterior compartments of the leg, re- spectively. These compartments are responsible for dorsiflexion and eversion of the foot, and injury to these nerves would result in deficits in these move- ments. The tibial nerve lies superficially in the popli- teal fossa. This nerve innervates the posterior com- partment of the leg, so compression in this area would result in a loss of plantar flexion and weakness of inversion. The lateral compartment of the leg is in- nervated by the superficial fibular (peroneal) nerve and is mainly involved in eversion of the foot. The cutaneous branches of the superficial fibular (pero- neal) nerve emerge through the deep fascia in the anterolateral aspect of the leg and supply the dorsum of the foot. The anterior compartment of the leg is innervated by the deep fibular (peroneal) nerve and is mainly involved in dorsiflexion of the foot. The me- dial malleolus is an inferiorly directed projection from the medial side of the distal end of the tibia. The tibial nerve runs near the groove behind the medial malleo- lus, and compression at this location would result in loss of toe flexion, adduction, abduction, and abduc- tion of the great toe.

Upon removal of a leg cast, a 15-year-old boy complains of numbness of the dorsum of his right foot and inability to dorsiflex and evert his foot. Which is the most probable site of the nerve compression that resulted in these symptoms? A. Popliteal fossa B. Neck of the fibula C. Lateral compartment of the leg D. Anterior compartment of the leg E. Medial malleolus

Femoral neck

What is the most common site of hip fracture?

talocrural joint

What joint is highlighted?

C. Herniation of the intervertebral disk at L4-5 results typically in compression of the L5 spinal nerve. The L4 spinal nerve exits at the L4-5 interver- tebral foramen, but the L5 spinal nerve is put under tension as it passes the herniation to reach the L5-S1 foramen. Piriformis entrapment of the fibular (pero- neal) division of the sciatic nerve is relatively com- mon, but the dermatome affected here appears to be confined to the L5 distribution to the skin of the foot and also includes the superior gluteal nerve, which supplies the large hip abductors. S1 would involve loss of sensation on the lateral side of the foot and potential weakness in hip extension and plantar flex- ion. A posterior dislocation of the hip would be un- likely in this injury but, even so, would not result in these deficits. GAS 80, 82; GA 33-34

When he attempted to lift one side of his new electric automobile from the ground to demonstrate his strength, the 51-year-old male felt a sharp pain in his back and quickly dropped the vehicle. Upon examina- tion it is observed that the patient has deficits in sensa- tion on the dorsum and sole of his foot and marked weakness in abduction and lateral rotation of the lower limb. What was the nature of his injury? A. Piriformis syndrome, with entrapment of the sciatic nerve B. Disk lesion at L3-4 C. Disk lesion at L4-5 D. Disk lesion at L5-S1 E. Posterior hip dislocation

C: Popliteus. As described in the question, holding the upright posture during standing includes locking the knee in a stable position. Locking is a complex event in which the femur slightly hyperextends, glides posterior, and rotates medially on the tibial condyles. Therefore, unlocking the knee (necessary in shifting from standing to locomoting) must call for the reverse movements. The popliteus lies deep and obliquely across the posterior aspect of the knee, from the lateral condyle of the femur to the posterior aspect of the prox- imal tibia. It unlocks the knee by initiating flexion and later- ally rotating the femur on the tibia. Choice A (Biceps femoris) is incorrect. The biceps femoris descends from the ischium and femur, crosses the lateral posterior aspect of the knee, and attaches onto the head of the fibula. It extends the hip, flexes the knee after unlocking, and laterally rotates the leg when the knee is flexed. Choice B (Gastrocnemius) is incor- rect. The gastrocnemius attaches to the femoral condyles, crosses the posterior side of the knee, and inserts onto the posterior calcaneus via the calcaneal tendon (tendo calcaneus; Achilles tendon). It flexes the knee after unlocking and plantar flexes the foot. Choice D (Sartorius) is incorrect. This long strap-like muscle crosses the anterior thigh from lateral (ante- rior superior iliac spine) to medial (proximal medial tibia). Because of its oblique course, it contributes to flexion, lateral rotation, and abduction of the hip and flexion of the knee. While it does participate in flexion of the knee, it does not unlock the knee, but acts after the popliteus has unlocked the knee joint. Choice E (Plantaris) is incorrect. This very small muscle originates just above the popliteus, from the lower lateral supracondylar line of the femur. However, rather than following the line of the popliteus, it descends through the leg to attach onto the posterior calcaneus. While the planta- ris is generously described as participating in flexion of the knee and plantar flexion of the foot, in reality it contributes virtually no forces to those movements and may be primarily proprioceptive in function.

When standing upright, the femur moves into the locked position by slightly hyperextending, gliding posteriorly, and medially rotating on the tibial plateaus. Which of the following muscles acts to initiate the unlocking of the knee? (A) Bicepsfemoris (B) Gastrocnemius (C) Popliteus (D) Sartorius (E) Plantaris