Overview
The tibial nerve is one of the two terminal branches of the sciatic nerve, providing motor and sensory innervation to most of the posterior leg and foot.
Origin
Arises as the terminal branch of the sciatic nerve (roots L4, L5, S1, S2, and S3)
It lies superficial (or posterior) to the popliteal vessels, extending from the superior angle to the inferior angle of the popliteal fossa, crossing the popliteal vessels from lateral to medial side.
Course & Branches
- Arises as one of the terminal branches of the sciatic nerve at the apex of the popliteal fossa
- The other terminal branch, the common peroneal nerve, travels laterally after bifurcation
- Contents of the popliteal fossa (superficial to deep): tibial nerve, popliteal vein, popliteal artery, small saphenous vein, common peroneal nerve, and the popliteal lymph nodes
- As it descends through the midline of the popliteal fossa, it gives off:
- Branches to muscles in the superficial posterior compartment of the leg.
- Branches that contribute towards the medial sural nerve, which innervates the posterolateral aspect of the leg.
- The tibial nerve continues its course down the leg, deep to the plantaris muscle and two heads of the gastrocnemius to enter the tendinous arch of the soleus muscle.
- In the deep posterior compartment of the leg, the nerve continues its course on the posterior surface of the tibialis posterior muscle.
- At the foot, the nerve passes posteriorly and inferiorly to the medial malleolus, through the tarsal tunnel, between between the tibial vein and flexor hallucis longus.
- Proximal to the tarsal tunnel, the tibial nerve gives off its second sensory branch, the medial calcaneal nerve.
- The lateral calcaneal nerve arises from the sural nerve (which descends on the surface of the calcaneal tendon).
- Distal to the tarsal tunnel, the tibial nerve gives off its terminal branches, the medial and lateral plantar nerves, which continue to supply motor and sensory innervation to the plantar foot and travel in the 2nd layer of the foot.
- Medial plantar nerve – travels just deep to the abductor hallucis to branch into common plantar and eventually proper plantar digital nerves to the first through fourth digits.
- Lateral plantar nerve – travels obliquely to the lateral side of the foot deep to the flexor digitorum brevis and superficial to the quadratus plantae muscle. This nerve then gives off a deep branch, which supplies deep muscles of the foot, as well as a superficial branch which continues coursing laterally. This superficial branch of the lateral plantar nerve terminates as common and proper plantar digital nerves supplying the fourth and fifth digits.
- Immediately distal to the tarsal tunnel, the tibial nerve terminates by dividing into sensory branches, which innervate the sole of the foot.