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The bony component of the gluteal (buttocks) region consists of two pelvic bones (os coxae) joined anteriorly by the symphy-sis pubis and posteriorly by the sacrum. Each os coxa is composed of three fused bones: ilium, ischium, and pubis. The bones of the gluteal region contain foramina (notches), which serve as conduits for nerves and blood vessels that travel between the pelvis, gluteal region, perineum, and lower limb. Muscles of the gluteal region primarily act on the hip joint.
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Actions of the Hip Joint
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The hip joint is a synovial, ball-and-socket joint. The “ball” is the head of the femur, and the “socket” is the acetabulum of the pelvic bone. The motions of the hip joint are as follows (Figure 35-1A):
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- Flexion. Movement anterior in the sagittal plane.
- Extension. Movement posterior in the sagittal plane.
- Abduction. Movement away from the midline in the frontal plane.
- Adduction. Movement toward the midline in the frontal plane.
- Medial rotation. Movement toward the midline in the transverse or axial plane.
- Lateral rotation. Movement away from the midline in the transverse or axial plane.
- Circumduction. A combination of hip joint motions that produces a circular motion.
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The muscles of the gluteal region primarily act on the hip joint, producing extension, medial rotation, lateral rotation, and abduction. In addition to producing motion, the muscles of the gluteal region are important for stability of the hip joint as well as for locomotion.
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- Gluteus maximus muscle. Attaches proximally on the ilium behind the posterior gluteal line, the sacrum, the coccyx, and the sacrotuberous ligament; distally, the muscle attaches at the iliotibial tract and the gluteal tuberosity of the femur. The gluteus maximus muscle is a powerful extensor of a flexed femur at the hip joint and a lateral stabilizer of the hip joint. The inferior gluteal nerve (L5, S1, S2) innervates this muscle.
- Gluteus medius muscle. Attaches proximally on the ilium between the anterior and posterior gluteal lines; distally, the muscle attaches on the greater trochanter of the femur. The gluteus medius muscle abducts and medially rotates the femur at the hip joint. In addition, the gluteus medius holds the pelvis secure over the stance leg, preventing pelvic drop on the opposite swing side during gait. The superior gluteal nerve (L4, L5, S1) innervates this muscle.
- Gluteus minimus muscle. Attaches proximally on the ilium between the anterior and posterior gluteal lines; distally, the muscle attaches on the greater trochanter of the femur. The action of the gluteus ...