Tibia nerve is the larger terminal branch of the sciatic nerve with root values of 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. It gives off branches as shown below:
- Cuteneous branches - Tibial nerve also gives off a cutaneous nerve called the sural nerve from the middle of the popliteal fossa and exits at the inferior angle. It supplies the skin of the lower half of the back of the leg and lateral border of the foot until the tip of the little toe.
- Articular branches - There are three articular branches arises from the upper part of the fossa: superior medial genicular nerve (located on the surface of medial condyle of femur, middle genicular nerve (pierces the posterior capsule of the knee joint to supply the structures located in the intercondylar notch of the femur, and inferior genicular nerve (runs along the upper border of the popliteus to reach the medial condyle of tibia).
Back of the leg
At the inferior angle of the popliteal fossa, tibial nerve passes deep to the tendinous arch of soleus to enter the back of the leg. In the leg, it runs downwards and medially to reach the posteromedial side of the ankle, midway between the medial malleolus and medial tubercle of the calcaneum. It terminates deep to the at the origin of the abductor hallucis by dividing into medial and lateral plantar nerves to supply the foot. The tibial nerve gives off several branches to supply the back of the leg:
- Muscular branches - Supplies tibialis posterior, flexor digitorum longus, flexor hallucis longus, and deep part of soleus.
- Cutaneus branches - The medial calcaneal nerve pierces the flexor retinaculum to supply the skin of the back and lower surface of the heel.
- Articular branches - Supplies the ankle joint
In the foot, the nerve terminates by dividing into medial and lateral plantar branches.
- Lateral plantar nerve - It is the smaller terminal branch of the tibial nerve. It courses laterally and forward until the base of fifth metatarsal bone, where it divideds into superficial and deep branches. Its distribution resembles to the distribution of ulnar nerve in the hand. The main trunk of the nerve supplies two muscles: flexor digitorum accessorius and . This nerve also supplies the skin of the sole. The superficial branch is divided into medial and lateral branches. The lateral branch supplies three muscles: , 3rd and 4th interossei, and the skin over the lateral side of the toe. The medial branch communicates with the medial plantar nerve and supplies the skin over the fourth interdigital cleft. The deep branch supplies the 2nd, 3rd, and 4th , first and second plantar interossei and adductor hallucis.