Along, thick, fleshy muscle extending from the superior part of the croup to the stifle. It is narrow above and widens out below, where it is divided into three segments.

Origin. - From the superior spines of the sacrum, the sacro-sciatic ligament, the gluteal and coccygeal fascia, and the tuberosity of the ischium.

Insertion. - By the three lower divisions: (l) Into the anterior part of the patella or knee-cap; (2) into the crest of the tibia; (3) into the fascia of the leg.

This muscle is maintained in its position behind the femur by a strong band of connective tissue which attaches it to the upper and posterior part of that bone.

Action, - It flexes the tibia or leg-bone on the femur, and, acting with its fellow on the opposite side, it assists in supporting and balancing the body in the act of rearing.