A 34-year-old man is evaluated in the emergency department due to difficulty walking. He was installing new shingles on his roof when he fell to the ground and sustained a puncture injury to his right leg. On physical examination, the right foot is dorsiflexed and everted. The patient is unable to stand on his tiptoes. Muscular strength at the knee and hip appear intact. Pedal and tibial pulses are +2 and symmetric. X-rays of his right leg are negative for fracture. This patient is most likely to have sensory loss over which of the following areas?

Question

A 34-year-old man is evaluated in the emergency department due to difficulty walking.  He was installing new shingles on his roof when he fell to the ground and sustained a puncture injury to his right leg.  On physical examination, the right foot is dorsiflexed and everted.  The patient is unable to stand on his tiptoes.  Muscular strength at the knee and hip appear intact.  Pedal and tibial pulses are +2 and symmetric.  X-rays of his right leg are negative for fracture.  This patient is most likely to have sensory loss over which of the following areas?

Quizplus · Accepted Answer

11ec160b_35f4_f5d6_9249_c3510257e7f0_MD0001_00 The tibial nerve is the large medial branch of the sciatic nerve and descends through the popliteal fossa together with the popliteal vein and artery. It then traverses the posterior compartment of the leg deep to the soleus muscle. After providing motor innervation to the posterior compartment muscles, the nerve enters the plantar aspect of the foot through the tarsal tunnel (between the flexor retinaculum and medial surfaces of the talus and calcaneus). Here, it divides into the medial and lateral plantar nerves, providing sensory innervation over the sole of the foot and motor innervation to the intrinsic foot muscles. Injury to the nerve at the popliteal fossa (eg, deep penetrating trauma, knee surgery) can cause weakness on foot plantarflexion because the nerve innervates the gastrocnemius, soleus, and plantaris muscles. Weakness may also be evident on foot inversion (eg, tibialis posterior muscle) and toe flexion (eg, flexor digitorum longus and flexor hallucis longus muscles). Consequently, patients often present with the foot held in a calcaneovalgus position (eg, dorsiflexed and everted). In contrast, injury to the tibial nerve at the tarsal tunnel may cause sensory loss over the sole with intrinsic foot muscle weakness. However, plantarflexion and inversion remain intact as fibers innervating these muscles branch off more proximally. (Choice A) The cutaneous branches of the femoral nerve innervate most of the skin over the anterior thigh. (Choice B) The superficial peroneal nerve innervates the lateral leg and dorsum of the foot, except for the skin between the great toe and second toe, which is innervated by the deep peroneal nerve. (Choice C) The medial aspect of the foot is innervated by the superficial peroneal nerve, a branch of the common peroneal nerve, and by the saphenous nerve. (Choice D) Cutaneous branches of the saphenous nerve innervate the skin of the medial leg. The saphenous nerve is a branch of the femoral nerve and courses to the medial leg together with the great saphenous vein. Educational objective: The tibial nerve may be injured at the level of the popliteal fossa due to deep penetrating trauma or knee surgery. Patients typically have weakness on foot plantarflexion, foot inversion, and toe flexion, with sensory loss over the sole. __________ References: Entrapment neuropathies of the lower extremity. (http://www.ncbi.nlm.nih.gov/pubmed/23542774) Lower extremity nerve trauma. (http://www.ncbi.nlm.nih.gov/pubmed/25150326)

A 34-Year-Old Man Is Evaluated in the Emergency Department Due