Overview
It covers most of the lateral surface of the thigh. In ruminants it is fused with the gluteus superficialis: the two form a single muscle, the gluteobiceps (m. gluteobiceps), which spreads from the sacrum and the ischiatic tuberosity to the stifle and the leg. Distally it divides into a cranial part and a caudal part, shown separately in the model.
In the carcass it is one of the hindquarter muscles that make up the outside round (silverside).
Origin
- Vertebral head: sacrum and broad sacrotuberous ligament, with the part corresponding to the gluteus superficialis.
- Pelvic head: ischiatic tuberosity (tuber ischiadicum).
Insertion
Through a broad aponeurosis continuous with the fascia lata and crural fascia:
- Cranial part: patella and lateral patellar ligament.
- Caudal part: tibial crest and crural fascia. It also gives off a tarsal tendon to the calcaneal tuber, which is part of the common calcanean tendon.
Action
Extends the hip. The cranial part extends the stifle and the caudal part flexes it; through the tarsal tendon it helps extend the tarsus.
Innervation
Caudal gluteal nerve (n. gluteus caudalis) for the vertebral head, and branches of the sciatic nerve (n. ischiadicus).
Clinical relevance
- The sciatic nerve runs deep to this muscle. Intramuscular injections into the gluteal region or caudal thigh of calves can injure it.
- Beef Quality Assurance guidelines call for no injections in the hindquarter, because injection-site lesions damage the most valuable cuts; injections go in the neck.
- In downer cows, prolonged recumbency compresses the large muscle masses of the pelvic limb and causes ischaemic myopathy, which worsens downer cow syndrome.
- Blackleg (Clostridium chauvoei) often affects the large hindquarter muscles of young cattle.