Anatomy of the female pelvis

The pelvis is a hard ring bone which supports and protects the pelvic organs and the contents of the abdominal cavity. It is structurally adapted for child bearing and delivery (See fig 1.3 below). There are three pelvic bones:

The ilium:The ilium is the major portion of the pelvis is composed of two bones, each called the ilium; one on either side of the backbone (or spinal column). When you place your hand on either hip, your hand rests on the iliac crest, which is the upper border of the ilium on that side. At the front of the iliac crest, you can feel the bony protuberance called the anterior superior iliac spine (a "protuberance" is something that sticks out, like a little hill or knob).

Ischium: The ischium is the thick lower part of the pelvis, formed from two fused bones; one on either side. When a woman is in labour, the descent of the fetal head as it moves down the birth canal is estimated in relation to the ischial spines, which are inward projections of the ischium on each side. On the Module Labour and Delivery Care, you will learn how to feel it to assess the progress of labor.

Pubic bones and the symphysis pubis: These are bones on either sides and form the front part of the pelvis. The two pubic bones meet in the middle at the symphysis pubic. The symphysis pubic is immediately below the hair covered pubic area. It is a very important landmark to measure the height of the uterus from the symphysis pubic to the fundus (top of the uterus see Figure1.2). This measurement enables you to estimate the gestational age of the fetus, i.e. how many weeks of the pregnancy have passed, and whether the fetus is growing at the normal rate.

Sacrum: The sacrum is a tapered, wedge-shaped bone at the back of the pelvis, consisting of five fused vertebrae (the small bones that make up the spinal column or backbone). The bottom of the sacrum is a tail-like bony projection called the coccyx. The upper border of the first vertebra in the sacrum sticks out, and points towards the front of the body; this protuberance is the sacral promontory; an important landmark for labor and delivery.