Part 6: THE PELVIS
The word pelvis means "basin" in Latin, and in a number of other languages (e.g., French and German) the same word is used for both.
The lesser (or "true") pelvis, as distinct from the abdomen proper (which includes the greater pelvis) is the subject of this section. It is that part of the trunk below the pelvic inlet. Its funnel-shaped cavity extends backward and downward from the abdominal cavity proper. The part of the abdominal cavity that lies between the iliac fossae is known as the greater (or "false") pelvis.
The thorax, abdomen, and pelvis are (together with the back) parts of the trunk. The thoracic and abdominal cavities are separated from each other by the diaphragm. The abdominal cavity proper and the true pelvic cavity are continuous across the plane of the pelvic inlet, or brim (see fig. 31-3). The combined abdominopelvic cavity varies in shape as it is traced downward.* Above, it appears kidney shaped in horizontal sections, because of the forward projection of the vertebral bodies (T.V.12 and L.V.1). Lower down, the shape is modified by the psoas muscles and becomes crescentic (L.V.2 to L.V.5; see figs. 26-3 and 29-5). In the sacral region, the transverse diameter diminishes (as the iliac fossae disappear), whereas the anteroposterior diameter increases (because of the backward slope of the sacrum; see figs. 26-2 and 31-3).
Pelvic structure and function are particularly important in obstetrics and gynecology. An interesting pictorial history has been compiled by H. Speert, Iconographia gyniatrica, Davis, Philadelphia, 1973.
*Symington in Quain's Elements of Anatomy, 11th ed., vol. 2, part 2, Longmans, Green, London, 1914, has provided instructive horizontal sections (fig. 68), sagittal sections (fig. 69), and models of the contained viscera (figs. 73 to 75).
Additional reading
Francis, C. C., The Human Pelvis, Mosby, St. Louis, 1952. A brief account.
Smout, C. F. V., and Jacoby, F., Gynaecological and Obstetrical Anatomy and Functional Histology, 3rd ed., Arnold, London, 1953. A good account, longer than the above.
Uhlenhuth, E., Problems in the Anatomy of the Pelvis. An Atlas, Lippincott, Philadelphia, 1953. Discussions and illustrations of selected topics, e.g., the retrovesical space.