Final answer:
The edge of the sacrum serves as attachment sites for ligaments that help support and immobilize the sacrum as it carries the weight of the body.
Step-by-step explanation:
The edge of the sacrum serves as an attachment site for several ligaments that help support and immobilize the sacrum as it carries the weight of the body. These ligaments include the anterior sacroiliac ligament, sacrospinous ligament, and sacrotuberous ligament. The anterior sacroiliac ligament supports the anterior side of the sacroiliac joint, while the sacrospinous ligament attaches to the ischial spine and the sacrotuberous ligament attaches to the ischial tuberosity. These ligaments contribute to the formation of the greater and lesser sciatic foramina.