In Depth: Pelvis
The pelvic region is the area between the trunk — or main body — and the lower extremities, or legs.
The female pelvis is morphologically different (different in form) from a male’s but most of the differences are not apparent until puberty. The pelvic bones are larger and broader as they have evolved to create a larger space for childbirth.
The most noticeable differences are the width of the pubic outlet, the circular hole in the middle of the pelvic bones, and the width of the pubic arch, or the space under the base of the pelvis.
The bones of the pelvis are the hip bones, sacrum, and coccyx. Each hip bone contains three bones — the ilium, ischium, and pubis — that fuse together as we grow older. The sacrum, five fused vertebral bones, joins the pelvis between the crests of the ilium. Below the sacrum is the coccyx, or tailbone, a section of fused bone that is the end of the vertebral column. The pelvis forms the base of the spine as well as the socket of the hip joint.
The hip joint is a ball-and-socket joint created by the femur and a part of the pelvis called the acetabulum. This joint and its ability to rotate in many angles is one of many pieces of anatomy that allows humans to walk.
The external female genitals include the vaginal opening, clitoris, urethra, labia minora, and labia majora. Collectively, these parts are called the vulva.
The vaginal opening is also home to the urethra, the tube through which the body expels urine. It is an extension of the ureters, or tubes that deliver urine from the bladder. The bladder is situated below the uterus.
The uterus is a pear-shaped, hollow organ where a fetus would develop prior to being born. Eggs, the female reproductive cells, are produced in the ovaries. A tube leads from each ovary to the uterus. These tubes are called the oviducts, or fallopian tubes.
The pelvic region also holds several digestive organs. These include the large intestine and small intestine. Both are vital to digesting food and expelling solid waste. The large intestine ends in the rear of the pelvis at the anus, a sphincter muscle that controls the disposal of solid waste.
The intestines are supported by a series of muscles known as the pelvic floor. These muscles also help the anus function and help push a baby through the vaginal opening during childbirth.