Leg and Foot Practice Quiz
A long distance runner complained of swelling and pain of his shin. At physical examination, skin testing showed normal cutaneous sensation of the leg. However, muscular strength tests showed marked weakness of dorsiflexion and impaired inversion of the foot. Which nerve serves the muscles involved?
Deep fibular nerve ---------------- The deep fibular nerve provides motor innervaton to the anterior compartment of the leg. This compartment contains tibialis anterior, a muscle that allows for dorsiflexion and inversion of the foot. If a patient is unable to dorsiflex the ankle, he or she will have foot drop. When the deep fibular nerve is damaged, cutaneous sensation to the leg and foot is normal, except for the loss of sensation on the web of skin between the first and second toe. This is the only place were the deep fibular nerve supplies cutaneous innervation. This patient probably has anterior compartment syndrome, which occurs when the muscles in the anterior compartment of the leg swell and press on the bone or fascial lining. Eventually, this swelling can compress the deep fibular nerve, leading to foot drop, or the anterior tibial artery, stopping blood flow to the dorsum of the foot. Injuries to the common fibular nerve often occur after fibular fracture because the common fibular nerve wraps around the neck of the fibula. If this nerve was injured, you would see the same symptom of foot drop, but it would be accompanied by a loss of cutaneous sensation to the anterolateral aspect of the leg and dorsum of the foot. The sciatic nerve branches to form the common fibular and tibial nerve. An injury to this nerve would damage all of the compartments in the leg. The superficial fibular nerve innervates the lateral compartment of the leg, which everts the foot. It also provides cutaneous sensation to the distal third of the anterior leg and the dorsum of the foot, so an injury here would lead to a significant loss of cutaneous sensation. Finally, the tibial nerve innervates the posterior compartment of the leg. An injury to this nerve would impair plantarflexion of the foot.
A patient has stepped on a board with a long nail sticking up from it, and the nail penetrated the patient's foot between the bases of the first and second metatarsals. What artery is most likely injured at this location?
Deep plantar artery -------------- The deep plantar artery is a branch of dorsalis pedis, the major artery supplying blood to the dorsum of the foot. The deep plantar artery dives from the dorsum of the foot to the sole of the foot between the two heads of the dorsal interosseous muscle between the first and second toes. It then unites with the lateral plantar artery to form the plantar arterial arch. The arcuate artery is on the dorsum of the foot. It would be unlikely to injure this artery from the plantar surface. The medial plantar artery is also on the medial side of the foot and it does distribute to the area where the injury occured. However, the medial plantar artery supplies blood to the superficial plantar surface of the foot, and the scenario in the question points to an injury that would disturb deep structures in the foot. So, deep plantar artery is the best answer.
A construction worker lacerates the dorsum of his foot just below his ankle. Profuse bleeding that occurs would result from cutting which vessel?
Dorsalis pedis artery --------------------- The dorsalis pedis is an extension of the anterior tibial artery that supplies the dorsal aspect of the foot. (The name change occurs at the level of the ankle, so that's why this isn't the anterior tibial artery.) Dorsalis pedis travels on the dorsum of the foot, slightly toward the medial side, and it would be the artery most likely damaged by this injury. The lesser saphenous vein forms from the dorsal venous arch of the foot. It travels on the lateral side of the foot, and, at the ankle, passes posterior to the lateral malleolus. So, the lesser saphenous vein would not be traveling on the dorsum of the foot by the time it reached the ankle. The medial plantar artery is not found on the dorsum of the foot; it would not be damaged by this injury. Finally, the fibular artery is a branch of the posterior tibial artery. It supplies the lateral compartment of the leg and does not send blood to the foot.
A medical student goes for a swim while on vacation in Florida after final exams. A barracuda bites his foot, severing an artery on the dorsum of his foot just below his ankle. Which artery has been severed?
Dorsalis pedis artery -------------The dorsalis pedis is a continuation of the anterior tibial artery--the name change here occurs at the level of the ankle. Since the artery on the dorsum of the foot was cut just below the ankle, dorsalis pedis must have been the vessel that was injured. The deep plantar artery is a branch of dorsalis pedis--it supplies the deep foot, and reaches this area by passing through a space between the first and second metatarsals on the dorsum of the foot. The dorsal metatarsal arteries are small arteries that come off of the arcuate artery and travel to the individual digits. They supply the dorsum of digits, excluding the distal phalangeal segment. There is no such thing as a deep fibular artery, but it sounds good.
A pedestrian is struck by a car, and his fibular neck is fractured. There is no indication of foot drop, but he cannot evert his foot and the top of his foot is numb. This apparent nerve lesion would affect which of the following muscles?
Fibularis longus -------------- A fracture of the fibular neck commonly causes an injury to the common fibular nerve, which has two branches: the deep fibular nerve and the superficial fibular nerve. However, this case isn't as simple. If the common fibular nerve was damaged, the deep fibular nerve would also be impaired. This would mean that the anterior compartment of the leg would be denervated, and the patient would suffer from foot drop. But that's not happening here, so you know that the common fibular nerve must be intact. The superficial fibular nerve, however, innervates the lateral compartment of the leg which allows for eversion. It also provides cutaneous sensation to the dorsum of the foot. An injury to this nerve fits with the patient's symptoms. The superficial fibular nerve innervates fibularis longus and brevis, so D is your answer. Tibialis anterior and fibularis tertius are both muscles in the anterior compartment of the leg--they are innervated by the deep fibular nerve. You should know that this compartment of the leg is intact because there is no foot drop. Tibialis posterior is innervated by the tibial nerve--this nerve was not involved in the accident. Finally, adductor hallucis is a foot muscle innervated by the deep branch of the lateral plantar nerve, which is a branch of the tibial nerve.
Pain may result from friction of the tendon of which muscle that passes deep to the anterior fibers of the long plantar ligament.
Fibularis longus muscle ---------------- Remember: fibularis longus runs from the lateral side of the foot across the entire sole of the foot, traveling deep to the long plantar ligament. The friction between these two closely related structures may lead to discomfort. The tendon of tibialis posterior crosses behind the medial malleolus and enters the plantar surface of the foot on the medial side, inserting on navicular, the medial cuneiform, and metatarsals 2-4. The tendon of flexor digitorum longus travels posterior to the medial malleolus, and inserts on the bases of the distal phalanges of digits. The tendon of flexor hallucius longus also crosses behind the medial malleolus, travels under sustentaculum tali, and inserts on the base of the distal phalanx of the first toe. Finally, tibialis anterior does not really cross onto the plantar surface. It travels across the dorsum of the foot, and its tendon inserts on the medial surface of the medial cuneiform and the first metatarsal.
A worker falls from a height and lands on his feet. Radiographs reveal a fracture of the sustentaculum tali. The muscle passing immediately beneath it that would be adversely affected is the:
Flexor hallucis longus muscle ------------- The tendon of flexor hallucius longus passes under sustentaculum tali, creating a groove in the bone. The sustentaculum tali is a shelf-like, medial projection of the calcaneus, which supports the talus. So, if the sustenaculum tali was fractured, the tendon of flexor hallucis longus would be displaced from its usual position and the muscle would be affected. The fibularis longus tendon enters the foot on the lateral side. It grooves the cuboid bone and travels deep to the long plantar ligament to insert on the medial cuneiform bone. The tendon of flexor digitorum longus crosses onto the plantar surface anterior to sustentaculum tali and eventually divides into 4 tendons that insert into the bases of the distal phalanges of digits 2-5. The tendon from tibialis anterior crosses the dorsal side of the foot and inserts on the medial surface of the first cuneiform and the first metatarsal. Finally, the tibialis posterior tendon crosses under the foot on the medial side, anterior to both flexor hallucis longus and flexor digitorum longus. It inserts on navicular, the medial cuneiform, and metatarsals 2-4. So, you should not see any of these other tendons associated with sustenaculum tali.
A player is kicked on the front of his leg during a soccer game, and a large bruise develops. A hematoma deep to the crural fascia can create extreme pressure within the anterior compartment of the leg, compressing structures within it. The most likely finding resulting from this anterior compartment syndrome is:
Foot drop ------------ Anterior compartment syndrome leads to foot drop due to the compression of the deep fibular nerve. Since the deep fibular nerve innervates tibialis anterior, an important dorsiflexer, injuring this nerve will impair dorsiflexion and cause the foot to drop. Numbness on the dorsum of the foot would suggest an injury to the superficial fibular nerve. An inability to evert the foot might also be due to an injury to the superficial fibular nerve, since that nerve supplies the lateral, everter compartment. Damage to the deep fibular nerve might also impair inversion since that is an action of tibialis anterior, but this would be a more subtle finding. Also, remember that tibialis posterior is also an inverter, so that muscle might be able to compensate for the injury to the anterior compartment. Finally, an inability to plantarflex the foot would stem from damage to the tibial nerve and the posterior compartment.
The most usual site for feeling the pulsations of the dorsalis pedis artery in the foot is:
Just lateral to the tendon of extensor hallucis longus ------------------- The dorsalis pedis artery is the continuation of the anterior tibial artery which continues on to the dorsum of the foot. The name change from anterior tibial to dorsalis pedis occurs at the level of the ankle. As the artery crosses into the foot, it lies just lateral to the tendon of extensor hallucis longus, so that's where you would feel a pulse. See Netter Plate 513 for a picture. The pulse of the posterior tibial artery, which comes from the posterior compartment of the leg, might be felt behind the medial malleolus. The pulse of the fibular artery might be felt behind the lateral malleolus, but that pulse would be very weak. There are no special pulses associated with the tendon of fibularis tertius or the second dorsal metatarsal space.
While walking barefoot on the beach in Florida following final exams, a medical student steps on a sharp shell which punctures the sole of her foot. She notices that she can no longer spread her toes apart (without using her hands, that is). Which nerve must have been injured?
Lateral plantar nerve -------------- This medical student is unable to abduct her toes--this must mean that her dorsal interosseus muscles are denervated. These dorsal interosseus muscles are innervated by the deep branch of the lateral plantar nerve, so this must be the nerve that was damaged. The medial plantar nerve innervates muscles on the plantar surface of the foot, including abductor hallucis, flexor hallucis brevis, and flexor digitorum brevis. None of these muscles are responsible for abducting the toes. As far as the other nerves go... you should know that the lateral and medial plantar nerves are the branches of the tibial nerve that continue to the plantar surface of the foot. However, the tibial nerve proper innervates the posterior compartment of the leg, allowing for plantarflexion of the foot. The deep fibular nerve is the nerve that innervates the anterior compartment of the leg--it also continues to the dorsum of the foot and innervates extensor hallucis brevis and extensor digitorum brevis. Finally, note that the sural nerve provides cutaneous innervation to the skin of the posterior surface of the lower leg and the skin of the lateral side of the foot--it is not a motor nerve.
A soldier complains of foot pain following a 50 mile hike. Upon examination, the physician diagnoses tendonitis of the fibularis longus tendon. Because the tenderness is located deeply on the sole of the foot, it appears that the irritation occurred where the tendon lies against bone, covered by a structure called the:
Long plantar ligament ---------------- Remember: the fibularis longus tendon enters the foot on the lateral side, then arches across the foot to insert on the medial cuneiform and the base of the first metatarsal. The long plantar ligament lies directly over this tendon. The long plantar ligament is a deep structure that connects calcaneus with cuboid and the bases of the lateral three metatarsals. If the fibularis longus tendon was inflamed, the long plantar ligament might also be affected. The plantar aponeurosis is a very superficial structure that covers and protects the sole of the entire foot--it is not closely associated with deep structures like the long plantar ligament. The short plantar ligament (also called the calcaneocuboid ligament) connects calcaneus and cuboid. The spring ligament connects sustantaculum tali with the inferior surface of navicular. Finally, the tendon of tibialis posterior enters the foot after traveling posterior to the medial malleolus and inserts on navicular, the medial cuneiform, and metatarsals 2-4.
In an accident involving farm machinery, a farmer recieves a cut on the dorsum of his ankle. As you inspect the wound and test for functional and sensory deficits, you find that no tendons have been cut, but the dorsalis pedis artery and the accompanying nerve have been cut. You would expect to find:
Numbness between the first and second toes ---------------- The nerve running with the dorsalis pedis artery is the deep fibular nerve. This nerve innervates the anterior compartment of the leg and the extensors on the dorsum of the foot. At the point where it was cut, the nerve had already given off all its branches to the anterior compartment of the leg. So, the farmer should still be able to dorsiflex his foot (preventing foot drop), and all of the muscles that invert his foot should be intact. Although extensor hallucis brevis (on the dorsum of the foot) has been denervated, extensor hallucis longus is in the anterior compartment of the leg, and that muscle should still be able to extend the great toe. However, the deep fibular nerve would have been cut before it could supply fibers to the area of cutaneous innervation between the first and second toe. So, there would be numbness in that area of skin. Club foot is a congenital anomaly which refers to a foot that has been twisted out of position. In cases of club foot, the foot is inverted, the ankle is plantarflexed, and the forefoot is adducted.
A construction worker steps on a board with a nail in it. The nail pierces the sole of his boot and enters his foot 2 cm anterior to his calcaneal tuberosity, at the middle of the width of his foot. Before reaching bone, the nail would pass through, in order:
Skin, plantar aponeurosis, flexor digitorum brevis, quadratus plantae, long plantar ligament ------------------------- 2 cm anterior to the calcaneal tuberosity, the nail would pass through skin, the plantar aponeurosis, flexor digitorum brevis (a superficial muscle), quadratus plantae (a deeper muscle), and the long plantar ligament. See the pictures in Netter plates 496-500 to get a better idea of this. The calcaneometatarsal ligament is the lateral band of the plantar aponeurosis--it is on the lateral part of the foot, and would not be found at the "middle of the width of his foot." Tendons of flexor digitorum longus are found far anterior in the foot--not just 2 cm anterior to the calcaneal tuberosity. The transverse metatarsal ligaments are also found far anterior in the foot, at the distal ends of the metatarsals.
A deep laceration, 2 cm in length, immediately posterior to the medial malleolus, may injure which structures?
Tendon of tibialis anterior Tendon of digitorum longus Posterior tibial artery Tibial nerve Tendon of flexor hallucis longus "Tom, Dick, ANd Harry" -------------------------- The flexor retinaculum is immediately posterior to the medial malleolus. So, any of the tendons or structures coming from the posterior compartment and crossing under flexor retinaculum to the plantar surface of the foot might be injured. The fibular artery is a branch of the posterior tibial artery that delivers blood to the lateral compartment of the leg. It does not cross into the foot, and it is nowhere near the medial malleolus. So that's your answer. All of the other listed structures are coming from the posterior, flexor compartment--these structures are all organized behind the flexor retinaculum in a very characteristic way. From anterior to posterior the structures are: tendon of Tibialis posterior, tendon of flexor Digitorum longus, posterior tibial Artery (and vein), tibial Nerve, and tendon of flexor Hallucis longus. So, T, D, A, N, H equals Tom, Dick, ANd Harry. This is an important relationship to remember!
While at the beach in Florida after final exams, a medical student steps on a stingray, which responds by stinging her in the ankle. The stinger pierces the skin, subcutaneous tissue, and flexor retinaculum of the ankle. Which other structure passing under the retinaculum may be injured?
Tibial nerve ---------- The flexor retinaculum is immediately posterior to the medial malleolus. The structures which pass under the flexor retinaculum are coming from the posterior compartment of the leg to enter the foot. These tendons, vessels, and nerve are all organized behind the flexor retinaculum in a very characteristic way. From anterior to posterior the structures are: tendon of Tibialis posterior, tendon of flexor Digitorum longus, posterior tibial Artery (and vein), tibial Nerve, and tendon of flexor Hallucis longus. Tom, Dick, ANd Harry! Out of all the answer choices, the tibial nerve is the only one which lies behind the flexor retinaculum, so that's your answer. Tibialis anterior is in the anterior compartment of the leg--its tendon just crosses under the extensor retinaculum to enter the dorsum of the foot. The anterior tibial artery is also in the anterior compartment of the leg. It crosses the ankle under the extensor retinaculum and enters the dorsum of the foot as dorsalis pedis. Quadratus plantae is a deep muscle of the plantar surface of the foot--it insures that the tendons from flexor digitorum longus flex the toes properly. The plantar arterial arch is a structure that supplies blood to the deep foot. None of these other structures are associated with the flexor retinaculum.
The lateral plantar nerve is a branch of which nerve?
Tibial nerve ------------- The lateral and medial plantar nerves are both branches of the tibial nerve. These branches continue to the plantar surface of the foot, innervating the muscles on the plantar surface of the foot and providing cutaneous innervation to the skin of the sole. The deep fibular nerve innervates the anterior compartment of the leg, the muscles on the dorsum of the foot, and provides sensory innervation to the web of skin between the first and second toe. The femoral nerve innervates the anterior (quadriceps) compartment of the thigh, which allows for extension at the knee. The saphenous nerve is a branch of the femoral nerve that travels with the great saphenous vein; it provides cutaneous innervation to the skin of the medial side of the leg and medial side of the foot. The sural nerve is a cutaneous nerve that provides sensory innervation to the skin of the posterior surface of the lower leg and the skin of the lateral side of the foot.
Your patient was struck by a car's bumper as she crossed the street, and her fibular neck is broken. After the bone has healed, she has "foot drop", i. e. she cannot dorsiflex her foot, and so it flops onto the ground during walking. Denervation (paralysis) of which of the following muscles would be associated with foot drop?
Tibialis anterior --------------- Tibialis anterior is the major dorsiflexer of the foot--if it is damaged, you will observe foot drop. It is found in the anterior compartment and is innervated by the deep fibular nerve. This patient probably damaged her common fibular nerve in the accident. This nerve wraps around the neck of the fibula before giving off its two branches: the deep fibular nerve and the superficial fibular nerve. You might hypothesize that this patient would also have a loss of cutaneous sensation on the distal third of the anterior leg and the dorsum of the foot, since those are the areas that receive cutaneous innervation from the superficial fibular nerve. None of the other muscles listed are dorsiflexers. Fibularis longus and brevis evert and plantarflex the foot; tibialis posterior plantarflexes and inverts the foot; popliteus flexes and rotates the leg medially so that the knee can unlock.
Compression of the lateral plantar nerve as it passes between the flexor digitorum brevis and quadratus plantae could result in weakness of which actions?
Adduction of all toes Abduction of toes 2 through 5 -------------------- The medial plantar nerve innervates abductor hallucis, so this muscle would be saved if the lateral plantar nerve was disrupted. The muscles responsible for all the rest of the actions listed are innervated by the lateral plantar nerve, or its branch, the deep lateral plantar nerve: Adduction of the middle toe: plantar interosseus muscles (deep branch); Abduction of the little toe: abductor digiti minimi (lateral plantar); Adduction of the great toe: adductor hallucis (deep branch); Abduction of the middle toe: third dorsal interosseus muscle (deep branch).
A patient has been diagnosed with bone cancer in the fibula that necessitates its removal. Which muscles would be affected following removal of the fibula?
Biceps femoris Extensor digitorum longus Flexor hallucis longus Peroneus tertius ---------------- Flexor digitorum longus is the most medial muscle in the deep posterior compartment of the leg. This means that it takes origin from the middle half of the posterior surface of the tibia and is not attached to the fibula in any way. Biceps femoris inserts on the head of the fibula and the lateral condyle of the tibia. Extensor digitorum longus is a muscle on the lateral side of the anterior compartment of the leg. This means that it takes origin from the fibula, and would be affected by its removal. Flexor hallucis longus is the most lateral muscle in the posterior compartment, so it originates from the fibula, too. Finally, fibularis (peroneus) longus and brevis, the two muscles of the lateral compartment, both take origin from the fibula.
A patient with a fracture to the left upper tibia was treated with a plaster cast. A few days later he started to develop progressive numbness over the dorsum of the foot and weakness in dorsiflexion. The cast was quickly changed and the signs were attributed to nerve compression. The compressed nerve was most likely the:
Common fibular nerve ------------------- The common fibular nerve must have been compressed in the cast. You can figure this out by thinking about the two branches of the common fibular nerve. The first branch is the deep fibular nerve which innervates the anterior compartment of the leg and is responsible for dorsiflexion of the foot. The second branch, the superficial fibular nerve, innervates the lateral (everter) compartment and provides cutaneous innervation to the dorsum of the foot. The combination of symptoms (impaired dorsiflexion and a loss of cutaneous sensation on the dorsum of the foot) suggests that both nerves are injured. So the common fibular nerve, which both nerves branch from, must be the structure that was damaged. The tibial nerve innervates the posterior compartment of the leg--an injury to this nerve would result in an inability to plantarflex the foot. The obturator nerve innervates the medial compartment of the thigh--damage to this nerve would impair adduction of the hip. The sciatic nerve branches to the tibial and common fibular nerve--an injury to this nerve would result in a great motor and sensory deficit in the leg and thigh. Finally, the femoral nerve innervates the anterior compartment of the thigh--damage to this nerve would denervate the quadriceps and impair extension at the knee.
A car strikes a pedestrian on the lateral side of her leg. Following the accident, she has "foot drop". Her foot hangs loosely in plantar flexion when she raises it off the ground. She can still invert her foot, but cannot evert it. She can flex but not extend her toes. Which nerve is most likely to have been crushed in her accident?
Common fibular nerve -------------------- All of these symptoms are consistent with damage to the common fibular nerve, whose branches, the deep and superficial fibular nerves, innervate the anterior and lateral compartments. The anterior compartment is important for dorsiflexion. When the tibialis anterior of this compartment is denervated, you will see foot drop. This compartment also contains extensor hallucis longus and extensor digitorum longus. These muscles and their brevis counterparts on the dorsum of the foot (which are also innervated by the deep fibular nerve) are responsible for extending the toes. Since this function is also lost, it is clear that the injury has affected the deep fibular nerve. Finally, the loss of eversion suggests that the lateral, everter compartment has been damaged--it is innervated by the superficial fibular nerve. If the injury was only to the superficial fibular nerve, you would not expect foot drop or difficulty extending the toes. Instead, the main symptom would be a loss of cutaneous sensation over the distal third of the leg and the dorsum of the foot. An injury to the tibial nerve would lead to problems with plantarflexion due to denervation of the posterior compartment. The medial plantar nerve innervates structures in the foot and would not produce these symptoms. Finally, the sciatic nerve gives rise to the tibial and common fibular nerves. An injury to the sciatic nerve would lead to deficits in all the compartments of the leg.