Bones of the Pelvis and Lower Back  The skeletal system of the
lower abdomen, including the pelvis helps protect the spinal
cord, digestive and urogenital systems and other internal organs
such as the bladder, rectum, and in women, the uterus.  The
skeletal system of the lower abdomen includes the five lumbar
vertebrae in the small of the back. These vertebrae support more
weight than the...  Anatomy Explorer  Full Bones of the Pelvis
and Lower Back Description  [Continued from above] . . .
vertebrae above them. At the base of the lower spine is a large
triangular bone called the sacrum. Its narrow lower part joins
the coccyx, or tail bone. The sides of the sacrum are connected
to the iliums (the largest bones forming the pelvis). The iliac
crest forms the prominence of the hip. The pelvis is a ring of
bones in the lower trunk of the body, which is bounded by the
coccyx (tail bone) and the hip bones. The pelvis is made up of
three hip bones, which are joined by rigid sacroiliac joints to
the sacrum at the bac