The Pelvic Girdle

Consists of two halves fused at the pubic symphysis.

Each half is made of three fused bones, the ilium, ischium and pubis.

Each half has a cup-shaped cavity the acetabulum.

This articulates with the head of the femur to form a ball and socket joint.

Dorsally, the ilium articulates with the sacrum.

The ilium is above the acetabulum. It provides large surface area to which thigh muscles are attached.

Between the ischium and pubis is a hole, the obturator foramen. This is an aperture through which blood vessels, nerves and muscles pass.

This design is an adaptation to reduce the weight of the pelvic girdle and hence lighten the load to be supported by the hind limb.

The pubic symphysis is composed of flexible cartilage which permits widening of the female’s girdles when giving birth.

The ilium, ischium and pubis are fused to form the innominate bone.