Lab Study Questions: Leg and Ankle
Draw a cross section of the ankle at the level of the malleoli, and identify where each tendon which crosses the joint, lies in relation to the 4 quadrants (anterolateral, anteromedial, posterolateral, posteromedial).
draw this
A car strikes a pedestrian on the lateral side of her leg. Following the accident, she has "foot drop"/ her foot hands 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? 1. Common fibular 2. Tibial 3. Superficial fibular 4. Medial plantar 5. Sciatic
A. common fibular All of these symptoms are consistent with damage to the common fibular nerve, whose branches, the deep and the 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 are 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 the superficial fibular nerve, you would not expect foot drop or difficulty extending the toes. Instead, the main symptoms 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 plantar flexion 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.
A tennis player feels a "pop" in her calf as she is playing. Her calf becomes tender and there is some slight amount of swelling. Upon examination, her physician informs her that she has ruptured the slender tendon of small muscles that attaches to the calcaneus. She has apparently ruptured the: a. Gastrocnemius b. Plantaris c. Popliteus d. Soleus e. Tibialis posterior
B. Plantaris Plantaris is a very small muscle in the posterior compartment of the leg. It has a very long and thin tendon that attaches directly to the calcaneus -- it does not insert on the calcaneal tendon along with the gastrocnemius and soleus. Plantaris acts to flex the leg and plantarflex the foot, but it is not the major muscle responsible for either of these motions. Like the other muscles of the posterior compartment, it is innervated by the tibial nerve. Gastrocnemius and soleus are large muscles of the posterior compartment that attach to calcaneus via the thick calcaneal tendon. If that tendon was ruptured, the patient would have imparied plantarflexion and significant pain. Poplietus is a muscle on the posterior knee which allows the knee to rotate medially and unlock to initiate flexion of the knee. Tibialis posterior is also a muscle in the posterior compartment -- it plantarflexes and inverts the foot.
A patient has been diagnosed with bone cancer in the fibula that necessitates its removal. Which of the following muscles would be least affected following removal of the fibular? a. Biceps femoris b. Extensor digitorum longus c. Flexor digitorum longer d. Flexor hallucis longus e. Peroneus tertius
C. Flexor digitorum longus 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 fibular, and would be affected by its removal. Flexor hallucis longus is the most lateral muscle in the posterior compartment, so it originates from the fibular, too. Finally, fibularis (peroneus) tertius, a muscle from the anterior compartment but takes origin from the fibula.
Palpate navicular tubercle and calcaneus bones of the foot
Calcaneus = heel Navicular tubercle = palpate inferior and anterior to the medial malleolus
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", (she cannot dorsiflex her foot, and so it flops onto the group during walking). Denervation (paralysis) of which of the following muscles would be associated with foot drop? a. Fibularis longus b. Tibialis posterior c. Fibularis brevis d. Tibialis anterior e. Popliteus
D. tibialis anterior Tibialis anterior is the major dorsiflexor of the foot -- if it is damaged, you will observe the 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 fibular before giving off 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 for the superficial fibular nerve. None of the other muscles listed are dorsiflexors. Fibularis longus and brevis evert and plantarflex and rotates the leg medially so that the knee can unlock.
Palpate the tibialis anterior muscle.
PA: lateral condyle and superior half of lateral surface of tibia and interosseous membrane DA: medial and inferior surfaces of medial cuneiform and base of 1st metatarsal Innervation: deep fibular nerve Action: DF and inv of foot
Demonstrate inversion and eversion of the foot. At what joint does this motion occur?
Subtalar joint Sole of foot inward, outward
What kinds of activities or tasks would a person have trouble with if they had an injury to the tibial nerve at the level of the popliteal fossa?
Tibial nerve innervates the posterior compartment- foot plantar flexors Walking, standing on tip toes
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? a. Common fibular b. Deep fibular c. Sciatic d. Superficial fibular e. Tibial
b. Deep fibular nerve The deep fibular nerve provides motor innervation 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 where the deep fibular nerve supplied 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 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? a. Tibialis posterior b. Tibialis anterior c. Fibularis tertius d. Fibularis longus e. Adductor hallucis
d. Fibularis longus because superficial fibular nerve disrupted and we know the person didn't have foot drop so it isn't Tib ant 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 00 this nerve was not involved in the accident. Adductor hallucis is a foot muscle innervated by the deep branch of the lateral plantar nerve, which is a branch of the tibial nerve.
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: a. Numbness on the dorsum of the foot b. Inability to evert the foot c. Inability to invert the foot d. Foot drop e. Inability to plantarflex the foot
d. 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 dorsiflexor, 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 muscles 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.
Palpate medial and lateral malleolus
on sides of ankle
