pelvis /pel″viz/ pl. pelves [L, basin] , the lower part of the trunk of the body, composed of four bones, the two innominate bones laterally and ventrally and the sacrum and coccyx posteriorly. It is divided into the greater, or false, pelvis and the lesser, or true, pelvis by an oblique plane passing through the sacrum and the pubic symphysis. The greater pelvis is the expanded part of the cavity situated cranially and ventrally to the pelvic brim. The lesser pelvis is situated distally to the pelvic brim, and its bony walls are more complete than those of the greater pelvis. The inlet and outlet of the pelvis have three important diameters: anteroposterior, oblique, and transverse. The pelvis of a woman is usually less massive but wider and more circular than that of a man. Also called true pelvis.
