Definition:
The pelvic is shallow bony cavity through which the fetus must pass during labour.
Function:
The primary function of the pelvic girdle is to allow movement of the 
body, especially walking and running. It permits the person to sit and kneel. The women’s pelvis is adapted for child bearing and because of its increase width and rounded brim women are less speedy than men. The pelvis transmits the weight of trunk to the legs, acting as a bridge between the femurs.
The pelvis also takes the weight of the sitting body on to the Ischial tuberosities. The sacrum transmits the cauda equina and distributes the nerves to the various parts of the pelvis.
Pelvic bones:
There are four pelvic bones.
1. Two in nominate (nameless) or hip bones
2. One sacrum
3. One coccyx
Details:
Innominate bone:
Each innominate bone is composed of three parts.
1. The Ilium:
The Ilium is the large flared-out-part. When the hands are placed on the hip it rests of on the iliac crest, which is the upper part.
2. The Ischium:
The ischium is the thick lower part. It has a large prominence known as the ischial tuberosity, on which the body rests when sitting.
3. The pubic bone:
This bone forms the anterior part. It has a body and two oar like projection, the superior rams and the inferior ramus. The two public bones meet at the symphysis pubis and the two inferior rami form the pubic arch.
The sacrum:
The sacrum is a wedge shaped bone consisting of five fused vertebrae. The upper border of the sacral vertebrae just forward and is known as the sacral promontory. The anterior surface of the sacrum is concave and is referred to as the hollow of the sacrum. Laterally the sacrum extends into a wing or ala. Four pairs of holes or foramina pierce the sacrum and, through these, nerves from the cauda equina emerge to supply the pelvic organs. The posterior surface is roughened to receive attachments of muscles.
The coccyx:
The coccyx is a vestigial tail. It consists of four fused vertebrae forming a small triangular bone.
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