hipbone

The hipbone, also known as the os coxae or innominate bone, is a large, flattened bone forming the pelvis. Each side of the pelvis is comprised of a single hipbone, which fuses together in the front at the pubic symphysis and at the back to the sacrum. This fusion creates a strong, supportive structure. The hipbone is actually formed from the fusion of three distinct bones in childhood: the ilium, the ischium, and the pubis. The ilium is the largest part, forming the prominent upper wing of the hip. The ischium is the lower, posterior part, which we sit on. The pubis is the anterior, lower part, meeting its counterpart from the other side at the pubic symphysis.

The hipbone plays a crucial role in supporting the weight of the upper body and transmitting that weight to the lower limbs. It also serves as an attachment point for numerous muscles of the trunk and legs, essential for movement and posture. A key feature of the hipbone is the acetabulum, a deep, cup-shaped socket that articulates with the head of the femur (thigh bone) to form the hip joint. This ball-and-socket joint allows for a wide range of motion, including flexion, extension, abduction, adduction, and rotation of the leg. The pelvic girdle, formed by the two hipbones, sacrum, and coccyx, provides a protective cradle for the pelvic organs.