The tibial nerve is one of the terminal branches of the sciatic nerve. It is a mixed nerve containing both motor and sensory fibers, which innervates the skin of the posterolateral side of the leg and lateral side of the foot.

The tibial nerve emerges above the popliteal fossa, passes along the middle of the popliteal fossa, then runs between the superficial and deep flexor muscles, reaching the medial malleolus. Further, it turns around the medial malleolus and runs below the flexor retinaculum into the third osteofibrous channel and splits into two terminal branches - the medial plantar nerve and the lateral plantar nerve.

The lateral plantar nerve (also called the external plantar nerve) passes obliquely forward between the flexor digitorum brevis and quadratus plantae muscles to the lateral side of the foot. Near the abductor digiti minimi the lateral plantar nerve splits into a superficial and a deep branch.
- The superficial branch of the lateral plantar nerve gives off the common plantar digital nerves that split into three proper digital plantar nerves to innervate the plantar skin of the fourth and fifth toes.
- The deep branch innervates most of the deep muscles of the foot, including the adductor hallucis, opponens digiti minimi, quadratus plantae, plantar interossei and dorsal interossei muscles, as well as the third and fourth lumbrical muscles.
The medial plantar nerve runs below the adductor hallucis muscle, then between it and the flexor digitorum brevis. In the end, the medial plantar nerve splits into three common digital plantar nerves and seven proper digital plantar nerves. The medial plantar nerve innervates the medial muscle group of the foot - the abductor hallucis and flexor hallucis muscles - and muscles of the middle group of the foot - the flexor digitorum brevis and the first and second lumbricals. The terminal branches of the medial plantar nerve innervate the skin of the plantar side of the foot and the skin of first to third toe, and the medial surface of the fourth toe.

On its course, the tibial nerve also gives rise to several side branches, including the:

Medial sural cutaneous nerve
Articular branches
Muscular branches
Medial calcaneal branches

The medial sural cutaneous nerve arises at the upper region of the popliteal fossa, descends between the two heads of the gastrocnemius muscle and runs below the crural fascia. Further, this nerve at the middle of the lower leg pierces the crural fascia and unites with the lateral sural cutaneous nerve (a branch of the common peroneal nerve) to form the sural nerve.

The articular branches of the tibial nerve innervate the knee joint and the ankle joint. The muscular branches innervate the superficial and deep posterior muscles of the lower leg. And the medial calcaneal branches of the tibial nerve innervate the skin in the medial part of the calcaneal region.

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Tibial nerve and its branches