Gluteal region

The gluteal region, commonly known as the buttocks or glutes, is the posterior part of the pelvic area. It extends from the upper iliac crests to the lower gluteal fold of the skin. Medially, it is separated by an intergluteal cleft, while laterally, it is bordered by the hip region.

The gluteal region comprises of superficial and deep muscle groups. The superficial group includes the gluteus maximus, medius, and minimus muscles. The gluteus maximus, the largest muscle, gives the buttocks its rounded appearance. The gluteus medius and minimus originate from the external surface of the iliac bone, with the medius lying over the minimus. The gluteus maximus has a broad origin, involving the external surface of the ilium, sacrum, and sacrotuberous ligament.

The gluteus maximus inserts into the gluteal tuberosity of the femur and the iliotibial tract of the facia lata, causing lateral rotation of the thigh at the hip. It also extends the trunk when climbing stairs or standing up from a seated position. On the other hand, the gluteus medius and minimus insert into the greater trochanter of the femur, medially rotating the thigh at the hip. They also act as hip abductors, preventing the pelvis from dropping on the side of the unsupported limb, a condition known as the Trendelenburg sign, resulting in a ‘waddling gait’.

The tensor facia latae, another muscle in the gluteal region, originates from the iliac crest and inserts into the iliotibial tract, stabilizes the knee in extension.

Deep within this region, a group of short muscles originates medially from the hip bone and sacrum, crossing behind the hip joint and inserting into the greater trochanter of the femur. These muscles, including piriformis, superior and inferior gamelli, obturator internus and quadratus femoris, are responsible for lateral rotation at the hip joint.

The muscles of the gluteal region are innervated by branches of the sacral plexus, including the superior and inferior gluteal nerves, and several motor branches to the deep short lateral rotator muscles. The sacral branches pass through the greater sciatic foramen to reach the gluteal region since the plexus is located within the pelvic wall.

The sciatic nerve, the largest branch of the sacral plexus, can also be found beneath the gluteus maximus muscle in the buttocks. It traverses through the greater sciatic foramen, descends through the gluteal region, and further extends into the hamstrings, where it divides into the tibial and common peroneal nerves. The sciatic nerve innervates the hamstrings, leg, and foot.

Another significant branch of the sacral plexus is the pudendal nerve, which innervates the perineum. To reach the perineum, the pudendal nerve follows a lengthy path, passing through the greater sciatic foramen to enter the gluteal region and then traveling through the lesser sciatic foramen to reach the perineum.