The pelvic girdle is a complex set of bones that forms the pelvic area, which attaches the lower limbs to the axial skeleton at the hip region. The pelvic girdle is formed by the two hip bones, which are part of the appendicular skeleton, and the sacrum and coccyx (tailbone), which are part of the axial skeleton. The hip bone, or coxal bone, is found above the thigh, and each is made of three different bones that have fully fused in adults. Before birth each coxal bone consists of three separate bones: the ilium, ischium, and pubis. The ilium forms the upper region of the coxal bone; it is the largest of the three bones and is the most superior bone of the pelvic girdle. The iliac crest is the superior region of the ilium that can be palpated, or felt, when the hands are on the hips. The ischium is the middle bone that is inferior (lower) and posterior (in the back), and the pubis is the anterior bone of the pelvic girdle. Where the three bones fuse laterally, the acetabulum is found. The acetabulum is the socket of the hip joint that has a deep cavity and is where the femur (thigh bone) meets the pelvis. Posteriorly, the coxal bones join to the sacrum at the bottom of the vertebral column. At the anterior end of the pelvic girdle, the two coxal bones join together at the pubic symphysis, a cartilaginous joint where the two pubis bones meet at the midline.The major function of the pelvic girdle is to join the lower limbs to the axial skeleton, similar to the pectoral girdle joining the upper limbs to the axial skeleton. However, the pelvic girdle has little freedom of motion when compared to the pectoral girdle. This restricted mobility is a result of the deep joint cavity and strong ligaments and is important to keep the joint stabilized during locomotion while supporting the weight of the body. Another function of the pelvic girdle is to support and protect the organs, such as the reproductive organs, contained in the pelvic region. It also provides a site of attachment for muscles in the lower limbs.