A 27-year-old man was admitted
for neurologic evaluation of a gunshot wound received five days previously. A
9-mm bullet had passed through both the medial and lateral heads of the
gastrocnemius muscle. The exit wound on the lateral head of the muscle was
somewhat deeper than the entrance wound in the medial head. The bullet had not
struck bone or significant arteries although significant tissue damage,
suppuration, and swelling were found around the exit wound. Neurologic
examination revealed losses of dorsiflexion and eversion of the left foot. The
patient could not feel pinprick or touch on the dorsum of the left foot or
anterolateral surface of the left leg. Which of the following nerves was most
likely involved in the injury?
A. Sciatic nerve B. Femoral nerve C. Sural nerve D. Common peroneal nerve E. Tibial nerve
Common peroneal nerve -the common peroneal (fibular) nerve is the lateral terminal branch of the sciatic nerve. after arising near the apex of the popliteal fossa, it descends on the popliteus muscle and winds superficially around the fibular neck. it is extremely vulnerable in this position and is the most often injured nerve in the lower extremity. the common peroneal nerve innervates all muscles in the anterior and lateral compartments of the leg. in addition, it provides sensory innervation to the dorsum of the foot and the anterolateral surface of the legs via the superficial and sural/lateral sural cutaneous nerves, respectively. the tibial nerve innervates plantar flexors of the posterior compartment. the sciatic nerve generally divides into the tibial and common peroneal nerves superior to the popliteal fossa. damage to it might result in deficits in both plantar flexion and dorsiflexion. the femoral nerve innervates the quadriceps muscles of the anterior thigh. damage to it would impair flexion of the thigh at the hip.