10/04/2026
Posterior View of Sciatic Nerve and Its Branches
The sciatic nerve, the largest nerve in the body, arises from the sacral plexus (L4–S3) and exits the pelvis via the greater sciatic foramen inferior to piriformis. It descends deep to the gluteus maximus and travels along the posterior compartment of the thigh as a single trunk enclosed in a common sheath.
Within the thigh, the nerve contains two functionally distinct components: the tibial part (medial) and the common fibular part (lateral). The tibial component supplies the hamstring muscles semitendinosus muscle, semimembranosus muscle, and the long head of biceps femoris muscle as well as the hamstring part of adductor magnus muscle. The common fibular component innervates the short head of the biceps femoris.
At the superior angle of the popliteal fossa, the sciatic nerve divides into its terminal branches: the tibial nerve and common fibular nerve. The tibial nerve continues vertically through the posterior leg, supplying superficial and deep posterior compartment muscles including gastrocnemius muscle and soleus muscle, and terminates as the medial and lateral plantar nerves in the foot.
The common fibular nerve courses laterally along the popliteal fossa, winds around the neck of the fibula, and divides into superficial and deep branches. Cutaneous innervation of the posterolateral leg is provided by the sural nerve, formed by the union of the medial sural cutaneous nerve (from tibial) and the sural communicating branch (from common fibular). It continues to supply the lateral aspect of the foot.
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