Sciatic nerve - Anatomy

Innervation
Tibial division motor semitendinous semimembranous long head biceps femoris gastrocnemius popliteus plantaris soleus tibialis posterior flexor digitorum longus flexor hallucis longus sensory innervation none Peroneal division motor abductor hallucis flexor digitorum brevis flexor hallucis brevis foot lumbricals quadratus plantae flexor digiti minimi adductor hallucis foot interossei abductor digiti minimi sensory articular branch to knee joint sural nerve branch runs distal with the small saphenous vein anastomoses with a branch from the peroneal nerve continues distal on lateral aspect of the Achilles tendon terminates as the lateral dorsal cutaneous nerve of the foot common peroneal nerve motor short head of biceps femoris deep peroneal nerve motor leg tibialis anterior extensor digitorum longus peroneus tertius extensor hallucis longus foot extensor digitorum brevis (lateral terminal branch) extensor hallucis brevis (lateral terminal branch) sensory articular branch to the ankle joint medial terminal branch: 1st dorsal webspace superficial peroneal nerve motor lateral compartment of leg peroneus longus peroneus brevis sensory majority of skin on the dorsum of foot, excluding webspace between hallux and second digit (deep peroneal nerve) anterolateral distal 1/3 of leg
Origin
The sciatic nerve originates from lumbosacral plexus L4-S3 tibial division orginates from anterior preaxial branches of L4,L5,S1,S2,S3 peroneal division originates from from postaxial branches of L4,L5,S1,S2
Course
Exits sciatic notch runs anterior or deep to piriformis runs posterior or superficial to short external rotators (superior gemellus, inferior gemellus, obturator internus) Posterior leg It then runs down the posterior leg where it breaks into its three main divisions at the level of the mid thigh Terminal branches common peroneal nerve tibial nerve
Injury & Clinical Conditions
Iatrogenic Injury methods to prevent injury routine visual identification not advised in primary THA palpation recommended visual identification is recommended in revision THA hip extension, knee flexion decreases tension on nerve