Human Pelvis, Male and Female
Male pelvis (top) and female pelvis (bottom). The pelvis is stronger and more massively constructed than either the cranial or thoracic cavity. It is composed of 4 bones, the ossa innominata, forming sides and front, and the sacrum and coccyx, completing it behind. The female pelvis differs from that of the male in making it better adapted for giving birth. The most notable differences are that the female pelvis is wider in every direction, giving more room for the child to pass and shallower, which lessens the distance through which the child has to be propelled; and lastly, the bones are thinner and smoother.
Kimber, Diana C. Anatomy and Physiology for Nurses (New York, NY: The Macmillan Company, 1907)
Courtesy the private collection of Roy Winkelman