The gluteal tuberosity is a surface on the femur bone in the leg that serves as the attachment point for the gluteus maximus muscle. Found on the bone’s rear surface, the gluteal tuberosity forms the outside edge of the linea aspera, a raised bony ridge that runs vertically down the center of the femur’s posterior shaft. Along this border, the lowermost fibers of the gluteus maximus attach, thereby pulling the leg backward when the muscle contracts.
As the large, familiar muscle of the posterior hip, the gluteus maximus is the primary muscle of hip extension, or raising the leg posteriorly. It also performs the action of external rotation, turning the leg outward in the hip joint. This muscle originates in the central posterior pelvis on the sacrum or coccyx, the two lowermost bones of the spine, as well as the upper posterior ilium bone of the pelvis, with fibers flaring outward and downward. Most of these fibers cross behind the hip joint and insert into the iliotibial (IT) band, a length of fibrous tissue that runs the length of the outer thigh and provides an attachment point for many muscles of the thigh.
The deepest fibers of the gluteus maximus, however, affix to the gluteal tuberosity. These fibers belong to the lower portion of the muscle. They run parallel to those of the rest of the muscle, but instead of merging with the fibers of the IT band, they connect to the femur bone. Where the posterior shaft is slightly raised along the linea aspera, a ridge is present along either vertical border. The lateral ridge and the surface area of the side of the linea aspera form the insertion point for the gluteus maximus: the gluteal tuberosity.
When the gluteus maximus contracts, its fibers shorten and produce an upward and inward pull on the femur. Those fibers that contribute to the IT band extend toward the outer thigh, so they rotate the leg outward as they pull inward across the back of the thigh. The deeper fibers that attach to the gluteal tuberosity extend farther downward. These pull upward on the posterior thigh when the muscle contracts so that the leg is simultaneously extended behind the body. They are particularly active during explosive pushing-off movements, such as jumping upward out of a squat position, exploding off the line during a sprint race, or bounding up a flight of stairs, but they are also used during hip extension exercises like deadlifts.