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The bony component of the gluteal (buttocks) region consists of two pelvic bones (os coxae) joined anteriorly by the symphysis 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):
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.
Internal (medial) rotation. Movement toward the midline in the transverse or axial plane.
External (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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MUSCLES OF THE GLUTEAL REGION
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The muscles of the gluteal region primarily act on the hip joint, producing extension, medial rotation, lateral rotation, and abduction (Table 35-1). 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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