The gluteus maximus is the largest and most superficial of the three gluteal muscles, playing a crucial role in the movement and stabilization of the hip and trunk. It is known for its power and size, significantly contributing to the shape of the buttocks. The muscle is essential for various actions, including extending and laterally rotating the hip, and is heavily engaged in activities such as climbing, jumping, and running.
Location
The gluteus maximus is located in the posterior area of the hip, forming the bulk of the buttock region. It originates from the ilium, dorsal surface of the sacrum, and sacrotuberous ligament, extending down to insert into the iliotibial tract and the gluteal tuberosity on the posterior aspect of the femur. This extensive muscle covers the posterior hip area and contributes significantly to the contour of the posterior body profile.
Anatomy
Origin
The gluteus maximus originates from several points: the posterior aspect of the iliac crest, the back of the sacrum and coccyx, and the sacrotuberous ligament—a strong, fibrous structure connecting the sacrum to the ischial tuberosity.
Insertion
The muscle fibers converge into a broad, flat tendon that inserts in two main areas:
- Iliotibial tract (IT band): A thick band of connective tissue running along the outside of the thigh, from the hip to the lateral aspect of the knee.
- Gluteal tuberosity: A roughened area on the posterior side of the femur, just below the hip joint.
Structure
The gluteus maximus is the largest of the three gluteal muscles, forming the bulk of the buttock. It’s characterized by its broad, thick, and coarse appearance, which is necessary for its powerful actions. The upper portion of the muscle primarily acts on the hip, while the lower portion, which inserts into the iliotibial tract, influences lateral stability of the leg.
Relations
- Superficially: Covered by the fascia lata, which is a deep layer of connective tissue enveloping the thigh muscles.
- Deeply: Underneath the gluteus maximus are the smaller gluteal muscles (gluteus medius and minimus), several smaller deep rotator muscles, and the sciatic nerve, one of the longest and widest nerves in the human body.
- Laterally: The muscle extends to the iliotibial tract, which is related to the tensor fasciae latae muscle.
Blood Supply
The gluteus maximus receives blood from the superior and inferior gluteal arteries, which are branches of the internal iliac artery. These vessels ensure the muscle receives the oxygen and nutrients needed for its functions.
Innervation
The muscle is innervated by the inferior gluteal nerve, which originates from the sacral plexus, carrying fibers from the L5, S1, and S2 nerve roots. This innervation controls the contraction and movement functions of the muscle.
Function
The gluteus maximus muscle has several crucial functions related to movement and stability of the lower body:
- Hip Extension: The primary function of the gluteus maximus is to extend the hip joint, such as when moving from a sitting to a standing position, walking, or running uphill.
- Lateral Rotation of the Thigh: The muscle also assists in the lateral (external) rotation of the thigh at the hip joint, which is important for activities like turning the toes outward.
- Upper Body Support: The gluteus maximus plays a key role in maintaining the upright posture of the body, particularly when the trunk is inclined forward, by stabilizing the hip and lower back.
- Abduction of the Hip: While not its primary role, the gluteus maximus can assist in the abduction of the hip, moving the thigh away from the body’s midline.
Clinical Significance
The gluteus maximus holds substantial clinical significance due to its pivotal role in lower body mechanics and its impact on overall posture:
Muscle Weakness and Atrophy: Weakness or atrophy of the gluteus maximus can lead to altered gait patterns, lower back pain, and reduced stability in the hip joint, impacting daily activities and increasing the risk of falls.
Postural Issues: Due to its role in maintaining upright posture, dysfunction in the gluteus maximus can contribute to postural abnormalities, such as anterior pelvic tilt and lordosis, which can exacerbate lower back discomfort.
Rehabilitation and Physical Therapy: Strengthening the gluteus maximus is a common focus in physical therapy, especially for patients recovering from lower back, hip, or knee injuries. Effective rehabilitation can improve mobility, reduce pain, and prevent further musculoskeletal issues.
Injections and Surgeries: The gluteus maximus area is a site for intramuscular injections, requiring knowledge of its anatomy to avoid nerve damage, particularly to the sciatic nerve. Additionally, its significance is considered in surgeries related to the hip and pelvis to ensure muscle functionality is preserved or restored.
Sports Performance: Athletes often focus on strengthening the gluteus maximus to improve performance in running, jumping, and other activities requiring strong hip extension.
