Body Organs

The pelvis, so called from its resemblance to a basin ( L. pelvis ), is stronger and more massively constructed that either the cranial or thoracic cavity; it is a bony ring, interposed between the lower end of the spine, which it supports, and the lower extremities, upon which it rests. It is composed of four bones; the two ossa innominata , which bound it on either side and in front, and the sacrum and coccyx, which complete it behind. The pelvis is divided by an oblique plane passing through the prominence of the sacrum, the linea illio-pectinea, and the upper margin of the symphysis pubis into the false and true pelvis. The false pelvis is the expanded portion of the pelvic cavity which is situated above this plane. It is bounded on each side by the ossa ilii; in front it is imcomplete, preventing a wide interval between the spinous processes of the illia on either side, which is filled up in the recent state by the parities of the abdomen; behind, in the middle line, is a dee...

The uterus, or womb, is quite an amazing organ. Pear-shaped in appearance, and testing on its small end (the cervix) in the center of a woman’s pelvis, it houses and protects a fetus from implantation until birth. As the fetus grows during pregnancy , the uterus expands tremendously – from the size of a fist into a huge, muscular bag filling the woman’s entire abdomen. That bag can hold not only a full term baby, but a quart of fluid and a one-pound placenta besides. The Menstrual Cycle Every month, if the woman is not already pregnant, the inner lining of the uterus (the endometrium) goes through a process of renewal and preparation known as the menstrual cycle. Basically, the menstrual cycle is the way the woman’s uterus prepares to receive and nourish a fertilized ovum. The inner lining of the uterus thickens and grows, and the structure of its blood vessels changes. If an ovum does become fertilized that month and implants in the uterine lining, the uterus keeps its lining to no...