Overview
It covers most of the lateral surface of the thigh. It has a wider cranial part and a caudal part; the caudal part contributes a tarsal tendon to the common calcanean tendon.
Origin
Sacrotuberous ligament and ischiatic tuberosity (tuber ischiadicum).
Insertion
Through the fascia lata and crural fascia: patella, patellar ligament, tibial crest and, by its tarsal tendon, the calcaneal tuber.
Action
Extends the hip. The cranial part extends the stifle and the caudal part flexes it; the tarsal tendon extends the tarsus.
Innervation
Branches of the sciatic nerve (n. ischiadicus).
Clinical relevance
The sciatic nerve runs deep to this muscle, between it and the caudal thigh muscles. Intramuscular injections into the caudal thigh can injure it, so the quadriceps or the lumbar epaxial muscles are preferred.