The gluteus minimus is one of the three muscles that make up the buttocks. It is the smallest of the trio, which also includes the gluteus maximus and gluteus medius. The gluteus minimus is located beneath the gluteus medius, positioned deep within the outer layer of the buttocks.
Anatomically, it originates from the outer surface of the ilium, which is the broad, flaring portion of the pelvic bone, between the posterior and anterior gluteal lines. It then extends downward to insert into the anterior surface of the greater trochanter, which is the large, bony knob on the upper portion of the femur (thigh bone). This placement makes the gluteus minimus an important muscle for hip movement and stability.
Anatomy
The gluteus minimus is a crucial muscle located in the buttock region, specifically in the lateral part of the hip.
Origin
The gluteus minimus originates from the external surface of the ilium. It spans from just below the iliac crest (the top border of the hip bone) to the anterior (front) and inferior (lower) gluteal lines. These are specific lines or areas on the pelvic bone where muscle tissues attach.
Insertion
The muscle fibers of the gluteus minimus converge as they move laterally and downward, attaching to the anterior surface of the greater trochanter of the femur. The greater trochanter is a prominent, bony projection on the femur (thigh bone), where several hip muscles converge.
Structure and Layers
The gluteus minimus is situated beneath the gluteus medius and is often covered by it. It is the smallest of the three gluteal muscles, which also include the gluteus maximus and medius. The muscle has a fan-shaped structure, which allows it to cover a broad area on the hip bone before narrowing to attach to the femur.
Blood Supply
The blood supply to the gluteus minimus comes primarily from the superior gluteal artery, which branches off from the internal iliac artery. This artery also supplies the other gluteal muscles and provides the necessary nutrients and oxygen for the muscle’s function.
Innervation
The gluteus minimus is innervated by the superior gluteal nerve, which arises from the sacral plexus, with roots from the L4, L5, and S1 spinal nerves. This nerve not only supplies sensation but also controls the muscle’s movements.
Fascia and Adjacent Structures
The gluteus minimus is enclosed by the fascia lata, which is a deep layer of thick fibrous tissue that surrounds the muscles of the thigh. Above it, the muscle is overlapped by the gluteus medius, and together, they form the lateral aspect of the hip. Despite its smaller size compared to the gluteus maximus and medius, the gluteus minimus plays a significant role in the stability and movement of the hip.
Function
The gluteus minimus muscle plays several crucial roles in the function and movement of the hip and lower body. Its main functions include:
- Abduction of the Hip: The primary function of the gluteus minimus is to abduct the thigh, which means it helps to move the thigh away from the body’s midline. This action is crucial for activities such as walking, running, and side-stepping, contributing to the lateral stability of the pelvis.
- Medial (Internal) Rotation: When the hip is flexed, the gluteus minimus also assists in medially rotating the thigh, which means it helps turn the thigh inward. This motion is important for activities where turning the leg inward is necessary, such as positioning the feet while sitting cross-legged or during certain athletic movements.
- Stabilization of the Hip and Pelvis: The gluteus minimus works with the other muscles of the hip, including the gluteus medius and maximus, to stabilize the pelvis during gait (the process of walking). When one leg is lifted off the ground, the gluteus minimus helps to prevent the drooping of the opposite hip, a function known as maintaining pelvic stability. This is essential for maintaining balance and proper walking mechanics.
- Preventing Adduction of the Hip: By functioning as an abductor, the gluteus minimus also prevents excessive adduction (movement toward the body’s midline) of the hip. This action helps in maintaining proper leg alignment and balance during movement and standing.
Clinical significance
The gluteus minimus muscle holds considerable clinical significance, particularly in the diagnosis and treatment of lower limb and hip disorders.
- Pain and Dysfunction: The gluteus minimus can be a source of pain and dysfunction, often associated with conditions such as trochanteric bursitis, where inflammation near the hip causes pain, especially when lying on the affected side or during movement. Pain originating from the gluteus minimus is sometimes mistaken for sciatica, due to the similarity in the pain distribution.
- Gait Abnormalities: Weakness or dysfunction in the gluteus minimus can lead to alterations in walking patterns, such as a Trendelenburg gait, where the pelvis tilts downward on the side opposite to the weakened muscle when walking. This is because the muscle is essential for stabilizing the pelvis during the stance phase of gait.
- Postural Issues: Since the gluteus minimus contributes to pelvic stability, weakness in this muscle can lead to postural issues and lower back pain. It can alter the alignment and mechanics of the pelvis and lumbar spine, contributing to discomfort and functional limitations.
- Rehabilitation and Physical Therapy: In the context of rehabilitation, strengthening the gluteus minimus is a common objective in physical therapy, especially for patients recovering from hip surgery, knee pain, or lower back pain. Exercises targeting the gluteus minimus are often included in rehabilitation programs to improve hip stability, reduce pain, and enhance mobility.
- Surgical Considerations: During certain hip surgeries, care must be taken to avoid damaging the gluteus minimus, as it is crucial for hip function and stability. Its preservation is important for postoperative recovery and the prevention of hip abductor weakness.
