Branch of sciatic (larger of two branches) – begins in popliteal fossa passes superficial to popliteal artery and vein passes beneath semimembranosus, deep to popliteal vessels enters deep posterior compartment beneath soleus with posterior artery and vein (branch goes to posterior tibial muscle) continues distally between flexor digitorum longus and flexor hallucis longus muscles (supplies branches to both) above ankle becomes more superfical and lies medial to achilles tendon turns around back of medial malleolus between the tendons passes into foot under flexor retinaculum (tarsal tunnel) distal to tunnel, divides into calcaneal sensory, medial and lateral plantar branches/nerves.
In popliteal fossa, motor branches soleus, plantaris, popliteal and both heads of gastrocnemius muscles. Sural cutaneous nerve (also originates in popliteal fossa) between two heads of gastrocnemius combines with peroneal communicating branch forms sural nerve
Three branches go to knee (genicular branches)
From popliteal muscle branch crural interosseous branch innervates tibial periosteum