Anatomy clinical correlates: Leg and ankle

When it comes to the clinical correlates of the leg and ankle, there is so much more than just rolling our ankle or banging our shin bone. There are a variety of clinical conditions that affect these structures, and it's not until these conditions occur that we remember the importance of our lower limbs. So we hope you get a kick out of this video learning the clinical conditions affecting the leg and ankle!

First up, let’s discuss tibial nerve injury. The tibial nerve is the medial and larger branch of the sciatic nerve, and it often splits from the common fibular nerve at the apex of the popliteal fossa, eventually dividing into the medial plantar nerve and lateral plantar nerve which provide motor and sensory information to the foot.

Tibial nerve injuries can occur either proximally, at the popliteal fossa, or distally at the tarsal tunnel which is more common. Injury at the popliteal fossa is rare as the nerve is protected deep within soft tissue at this level. Mechanisms that may cause injury at the popliteal fossa are deep penetrating trauma, knee surgery, compression from a tumor or a Baker's cyst, and posterior knee dislocation.

An injury at the popliteal fossa affects the innervation of both the lower leg and the foot. Individuals can present with weakness in plantarflexion, inversion, and toe flexion of the foot, due to decreased innervation to the muscles in the deep compartments of the lower leg. Additionally, those affected can present with their foot in a calcaneovalgus position, or more simply in dorsiflexion and eversion. Injury at this level also impairs innervation to the intrinsic muscles of the foot and can also cause paresthesia to the sole of the foot.

On the other hand, there are distal tibial nerve injuries, most commonly at the tarsal tunnel. Distally the tibial nerve passes through the tarsal tunnel, between the medial malleolus and calcaneus deep to the flexor retinaculum. Injury at the tarsal tunnel can be caused by fractures or dislocations involving the talus, calcaneus, or medial malleolus.