Page 13 - 33Elctronic Book (3) Normal Labor

▪ I-The bony pelvis is composed of :
1- Pairs of bones (Hip bones) 2-Sacrum 3- Coccyx.

Two hipbones which is composed of:

A-Ilium B-Ischium C-Pubis

A-Ilium

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) and curving towards the front of the
body. 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).

B-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 labor, 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. The ischial spines are smaller and rounder in
shape in the woman’s pelvis than in that of the man.

C-Pubic bones and the symphysis pubis
The pubic bones on either side form the front part of the pelvis. The two pubic bones

meet in the middle at the pubic symphysis. (A symphysis is a very strong bony joint.)
The pubic symphysis is immediately below the hair-covered pubic mound that protects

the woman’s external genitalia.

2-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). At

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

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