Tibial Nerve

Origin

Typically, the tibial nerve arises from the sciatic nerve in the distal thigh, just proximal to the popliteal fossa, and is derived from the anterior divisions of the anterior rami of the fourth lumbar to the third sacral spinal nerves. It is the larger of the two branches of the sciatic nerve (the other branch being the common fibular nerve).

Course

The tibial nerve descends in the popliteal fossa, initially lateral to the popliteal artery. At the level of the knee, it becomes more superficial to the popliteal vessels and passes to the medial side of the popliteal artery. It passes over the popliteus muscle and passes anterior to the arch of the soleus muscle to enter the leg.

In the leg, the tibial nerve descends in the posterior compartment, accompanied by the posterior tibial arteries laterally. Initially it is deep to the soleus and gastrocnemius muscle, but distally, it is covered only by skin and underlying fascia. The tibial nerve also crosses the posterior tibial artery to lay lateral to it until it reaches the region of the medial malleolus where it bifurcates.

Branches

The tibial nerve gives rise to articular and muscular branches, as well as the crural interosseous nerve, medial sural cutaneous nerve, and the medial calcaneal branches. It terminates by dividing into the medial and lateral plantar nerves.

Supplied Structures

The tibial nerve, through its muscular branches, supplies the muscles of the posterior compartment of the leg. These include the gastrocnemius, soleus, plantaris, popliteus, flexor digitorum longus, flexor hallucis longus, and tibialis posterior muscles.

The medial plantar nerve provides motor innervation of the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, and the first lumbrical muscles.

The lateral plantar nerve provides motor innervation to the abductor digiti minimi, quadratus plantae, second to fourth lumbricals, adductor hallucis, plantar and dorsal interossei, and flexor digiti minimi brevis muscles.

The tibial nerve also supplies cutaneous innervation to the skin on the posterolateral aspect of the leg via its medial sural cutaneous nerve. It also supplies the skin of the medial plantar surface of the foot, including the first four digits via the medial plantar nerve; the lateral plantar surface of the foot, including the fifth digit, via the lateral plantar nerve; the heel of the foot via its medial calcaneal branches.