Human Pelvis

The human pelvis is the wide bone structure at the lower end of the trunk. It supports and contains the last portion of the digestive tract and the urogenital system. Large muscles of the thigh and hip are anchored to it. It articulates with the head of femur at the acetabulum cavity. 

The shape and dimensions of pelvis depend on the sexual differences and individual body size. The average width of female pelvis is 27 cm, while it is 24 cm in the male; this is called the intercristal diameter, extending from the lateral iliac crest of one hip bone to the other of the opposite side. The frontoposterior diameter and pelvic cavity are also wider in female by one and half centimeter.

Anatomical Description

The human pelvis is composed of the two hip bones, the sacrum, and the coccyx. They are all joined together into one anatomical unit by cartilage, ligaments, and joints. The widest part of each one of the hip bones is called the ilium. The upper edge of the ilium is the iliac crest, which runs from back to the frontolateral portion of the pelvis, curving around the side. On the lateral side, the hip bone features a concave cavity; the acetabulum, in which the head of femur fits snugly.

The foremost frontal portion of the hip bone is very narrow compared to the rest and is below the iliac crest; it is called the pubis. The pubis of each hip bone is joined to the one of the opposite side at a medial line by the pubic symphysis, which is a fixed joint made of cartilage. Meanwhile, the bone arch at the bottom and rear portion of the hip bone is called the ischium, which forms an opening referred to as the foramen obturatum. Powerful muscles of the medial side of thigh are attached to the ischium, such as the adductor magnus.

As a whole, the human pelvis can be divided into the greater pelvis and the lesser pelvis. The greater pelvis is bounded on the sides by the wing of the ilium, and posteriorly by the lower lumbar vertebra and the base of the sacrum. Its inferior boundary consists of the crest of the pubis and the frontolateral portion of crest of ilium; this inferior boundary is called the arcuate line of the pelvis.

The lesser pelvis, on the other hand, is located below the arcuate line. Its lateral walls are formed by the lower part of the bodies of the ilia and ischia, the posterior wall by the sacrum and coccyx, and the anterior wall by the two pubic bones.

Below, the female human pelvis, with its different parts labeled. It is wider than the male's.