Buttock

Structure

Each buttock contains three gluteal muscles, a thick layer of fat, and the sciatic nerve passing beneath. The ischial tuberosity is the bony point that bears weight when seated.

Function

The gluteus maximus, the largest muscle of the buttock, extends and laterally rotates the hip. Smaller gluteal muscles abduct and rotate the thigh and stabilize the pelvis in single-leg stance.

Clinical note

The upper outer quadrant of the buttock is the standard target for deep intramuscular injections, chosen to avoid the sciatic nerve and major blood vessels.