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.

Actions of the Hip Joint

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:

• 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.