Final answer:
The iliac spines serve as attachment points for muscles of the thigh and the ligaments supporting the sacroiliac joint. The anterior spines contribute to thigh movements, while the posterior spines support weight transfer and locomotion.
Step-by-step explanation:
The iliac spines are significant anatomical landmarks on the pelvic girdle that serve as attachment points for various structures. The anterior superior iliac spine and anterior inferior iliac spine are important bony landmarks located at the anterolateral aspect of the hip and serve as attachment points for the muscles of the thigh. These muscles are instrumental in movements such as hip flexion, abduction, and rotation. Posteriorly, the posterior superior iliac spine and the posterior inferior iliac spine provide attachment sites for the muscles and very strong ligaments that support the sacroiliac joint, which is vital for weight transfer between the upper body and lower limbs.
The pelvic girdle provides structural strength thanks to the compact articulations of its associated bones and ligaments. Ligaments including the anterior and posterior sacroiliac ligaments, sacrospinous ligament, and sacrotuberous ligament, fortify the connection between the hip bone and sacrum, effectively supporting the body's weight and enabling locomotion.