The gluteal region is an anatomical area located posteriorly to the pelvic girdle, at the proximal end of the femur. The muscles in this region move the lower limb at the hip joint and are broadly divided into two groups—superficial abductors and extenders, and deep lateral rotators.
The superficial abductors and extenders comprise of a group of large muscles that abduct and extend the femur, and include the gluteus maximus, gluteus medius, gluteus minimus and the tensor fascia lata.
The deep lateral rotators are a group of smaller muscles that mainly act to laterally rotate the femur. Muscles that are included in this group are the quadratus femoris, piriformis, gemellus superior, gemellus inferior and obturator internus.
The superficial muscles in the gluteal region consist of the three glutei and the tensor fascia lata. They mainly act to abduct and extend the lower limb at the hip joint.
The gluteus maximus is the largest of the gluteal muscles. It is also the most superficial, producing the shape of the buttocks.
Attachments—originates from the gluteal (posterior) surface of the ilium, sacrum and coccyx. The fibres slope across the buttock at a 45 degree angle and insert onto the iliotibial tract and gluteal tuberosity of the femur.
Actions—it is the main extensor of the thigh, and assists with lateral rotation. However, it is only used when force is required, such as running or climbing.
The gluteus medius muscle is fan-shaped and lies between the gluteus maximus and the minimus. It is similar in shape and function to the gluteus minimus.
Attachments—originates from the gluteal surface of the ilium and inserts into the lateral surface of the greater trochanter.
Actions—abduction and medial rotation of the lower limb. It stabilises the pelvis during locomotion, preventing ‘dropping’ of the pelvis on the contralateral side.
The gluteus minimus is the deepest and smallest of the superficial gluteal muscles. It is similar in shape and function to the gluteus medius.
Attachments—originates from the ilium and converges to form a tendon, inserting to the anterior side of the greater trochanter.
Actions—abduction and medial rotation of the lower limb. It stabilises the pelvis during locomotion, preventing ‘dropping’ of the pelvis on the contralateral side.
The tensor fascia lata is a small superficial muscle which lies towards the anterior edge of the iliac crest. It functions to tighten the fascia lata, and so abducts and medially rotates the lower limb.
Attachments—originates from the anterior iliac crest, attaching to the anterior superior iliac spine (ASIS). It inserts into the iliotibial tract, which itself attaches to the lateral condyle of the tibia.
Actions—assists the gluteus medius and minimus in abduction and medial rotation of the lower limb. It also plays a supportive role in the gait cycle.
The superior gluteal nerve innervates the gluteus medius and the gluteus minimus. These muscles have an important role in stabilising the pelvis during locomotion. In the standing position, the gluteus minimus and medius contract when the contralateral leg is raised, preventing the pelvis from dropping on that side.
If the superior gluteal nerve is damaged, the previously described muscles are paralysed—and the pelvis becomes unsteady. A characteristic finding of gluteal muscle weakness is the Trendelenburg sign.
The Trendelenburg sign is produced when the patient is asked to stand unassisted on each leg in turn. In a positive sign, pelvic drop will occur on the unsupported leg. Pelvic drop can be recognised by observing the level of the iliac crests on both sides.
It is important to note that damage to the superior gluteal nerve can have serious consequences, including restrictive movement, walking difficulty, and pain. It is therefore important to be aware of the potential complications associated with this nerve, and to seek appropriate medical attention if any symptoms of damage become apparent.
The deep gluteal muscles are a set of smaller muscles located underneath the gluteus minimus. Their general action is to laterally rotate the lower limb, as well as stabilise the hip joint by ‘pulling’ the femoral head into the acetabulum of the pelvis.
The piriformis muscle is a key landmark in the gluteal region and the most superior of the deep muscles. It originates from the anterior surface of the sacrum, with its fibres travelling inferiorly and laterally through the greater sciatic foramen to insert onto the greater trochanter of the femur. It has the primary actions of lateral rotation and abduction, and is innervated by the nerve to piriformis.
The obturator internus forms the lateral walls of the pelvic cavity, and in some texts it is grouped with gemelli muscles and considered as one unit known as the triceps coxae. It originates from the pubis and ischium at the obturator foramen and travels through the lesser sciatic foramen, attaching to the greater trochanter of the femur. It is responsible for lateral rotation and abduction, and is innervated by the nerve to obturator internus.
The gemelli are two narrow and triangular muscles that are separated by the obturator internus tendon. The superior gemellus muscle originates from the ischial spine, while the inferior originates from the ischial tuberosity. Both attach to the greater trochanter of the femur, with associated actions of lateral rotation and abduction. The superior gemellus muscle is innervated by the nerve to obturator internus, while the inferior gemellus is innervated by the nerve to quadratus femoris.
The quadratus femoris is a flat, square-shaped muscle and the most inferior of the deep gluteal muscles. It originates from the lateral aspect of the ischial tuberosity and attaches to the quadrate tuberosity on the intertrochanteric crest, acting primarily to laterally rotate the lower limb. Nerve to quadratus femoris is responsible for its innervation.
The piriformis is an important anatomical landmark in the gluteal region, as it travels through the greater sciatic foramen and effectively divides the gluteal region into an inferior and superior part. This division determines the name of the vessels and nerves that supply the area, as the superior gluteal nerve and vessels emerge into the gluteal region just superior to the piriformis, with the inferior gluteal nerve and vessels emerging inferiorly. In addition, the piriformis can be used to locate the sciatic nerve, which enters the gluteal region directly inferior to the piriformis and is visible as a flat band approximately 2cm wide.
The superficial muscles in the gluteal region consist of the three glutei and the tensor fascia lata. These primarily act to abduct and extend the lower limb at the hip joint.
The gluteus maximus is the largest and most superficial of the gluteal muscles, producing the shape of the buttocks. It originates from the gluteal (posterior) surface of the ilium, sacrum and coccyx, with the fibres sloping across the buttock at a 45 degree angle and inserting onto the iliotibial tract and gluteal tuberosity of the femur. Its primary action is as the main extensor of the thigh, and it assists with lateral rotation, yet is only used in force production such as during running or climbing. It is innervated by the inferior gluteal nerve.
The gluteus medius muscle is fan-shaped and lies between the gluteus maximus and the minimus. It is similar in shape and function to the gluteus minimus, originating from the gluteal surface of the ilium and inserting into the lateral surface of the greater trochanter. Its primary actions are abduction and medial rotation of the lower limb, which it uses to stabilise the pelvis during locomotion, preventing 'dropping' of the pelvis on the contralateral side. The superior gluteal nerve is responsible for its innervation.
The gluteus minimus is the deepest and smallest of the superficial gluteal muscles, and is similar in shape and function to the gluteus medius. It originates from the ilium and converges to form a tendon, inserting to the anterior side of the greater trochanter. Its primary actions are abduction and medial rotation of the lower limb, and it is innervated by the superior gluteal nerve.
The tensor fascia lata is a small, superficial muscle located towards the anterior edge of the iliac crest. It functions to tighten the fascia lata, and so abducts and medially rotates the lower limb. It connects to the anterior superior iliac spine (ASIS) and to the iliotibial tract which attaches to the lateral condyle of the tibia. It also stabilises the pelvis during locomotion, preventing 'dropping' of the pelvis on the contralateral side. It is innervated by the superior gluteal nerve.
Underneath the tensor fasica lata are the deep gluteal muscles. The general action of these muscles is to laterally rotate the lower limb, as well as stabilise the hip joint by 'pulling' the femoral head into the acetabulum of the pelvis. The most superior of the deep muscles is the piriformis. It originates from the anterior surface of the sacrum and travels inferiorly and laterally via the greater sciatic foramen to attach to the greater trochanter of the femur. It functions to lateral rotate and abduct the lower limb and is innervated by the nerve to piriformis.
The obturator foramen is located laterally on the pelvic cavity and consists of the obturator internus and the gemelli muscles. The obturator internus originates from the pubis and ischium and travels through the lesser sciatic foramen to attach to the greater trochanter of the femur, functioning to lateral rotate and abduct the lower limb and is innervated by the nerve to obturator internus. The gemelli, separated by the obturator internus tendon, consists of the superior and inferior gemellus which originates from the ischial spine and ischial tuberosity respectively. Both attach to the greater trochanter of the femur and function to lateral rotate and abduct the lower limb, with the superior gemellus muscle being innervated by the nerve to obturator internus and the inferior gemellus being innervated by the nerve to quadratus femoris.
The most inferior of the deep gluteal muscles is the quadratus femoris. It is a flat, square-shaped muscle originating from the lateral aspect of the ischial tuberosity and attaches to the quadrate tuberosity on the intertrochanteric crest. It functions to laterally rotate the lower limb and is innervated by the nerve to quadratus femoris.
The piriformis muscle is a key anatomical landmark in the gluteal region. As this muscle travels through the greater sciatic foramen, it effectively divides the gluteal region into an inferior and superior part. This distinction is important as the superior gluteal nerve and vessels emerge into the gluteal region superiorly to the piriformis and vice versa for the inferior gluteal nerve. Additionally, the piriformis can be used to localise the sciatic nerve, which enters the gluteal region directly inferior to the piriformis and is visible as a flat band approximately 2cm wide.
In summary, the gluteal region is made up of the tensor fascia lata, the deep gluteal muscles of the piriformis, obturator internus, and quadratus femoris, and the gemelli which consists of the superior and inferior gemellus. These muscles function to stabilise the pelvis during locomotion, laterally rotate the lower limb, and help 'pull' the femoral head into the acetabulum of the pelvis. The piriformis is an important anatomical landmark in the gluteal region that can be used to divide the region into an inferior and superior part as well as localise the sciatic nerve.
