The pelvic girdle consists of multiple bones that function together as a single unit. Bones of the pelvic girdle include the triangular sacrum and coccyx (the most inferior sections of the spine) and the right and left innominate bones. The sacroiliac joints connect the sacrum to the right and left innominate to form a single unit.
Major features of the pelvis include the pubic symphysis, acetabulum, foramen obturatum, iliac crest, and anterior and posterior superior iliac spine.
Biomechanically, the pelvis is part of the torso. It is located at the base of the spine and provides an attachment point for the legs. It also serves as an anchor for the muscles of the hip, thigh, and abdomen.
The pelvis is part of the hip joints and it provides a base for the lumbar spine. The right and left innominate each have a cup-shaped acetabulum. The spine is attached to the pelvis on the superior surface of the sacrum (physically on the top, but anatomically called the base because it has an inverted triangular shape). These connections are supported by multiple ligaments and muscles that keep the joints from separating during activity.
