pelvis(redirected from false pelvis)
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the part of the skeleton that in mammals joins the posterior extremities and in man joins the lower extremities. The pelvis supports the spinal column and the entire upper part of the human body. It articulates with the femoral bones and hip joints. The pelvis consists of unpaired bones—the sacrum and coccyx—and of two paired pelvic (innominate) bones. The pubic bones are joined in front by the symphysis pubica and are joined in back with the sacrum by paired sacroiliac joints reinforced by strong ligaments. Each innominate bone consists of an iliac, ischial, and pubic bone that fuse together toward the end of the growth period; the site of fusion is covered by the cotyloid cavity. The female pelvis is wider and shallower than the male pelvis.
The pelvis is divided into the false and true pelvis. The false pelvis is bounded in front by the soft tissues of the anterior abdominal wall, in back by the spinal column, and on the sides by the ossa ilii. The true pelvis is bounded in front by the pubic bones, in back by the sacrum and coccyx, and on the sides by the ischial bones and soft tissues. The false pelvis contains the organs of the lower part of the abdominal cavity, and the true pelvis contains the rectum and bladder. In males, the true pelvis contains the prostate gland and seminal vesicles, and in females, the uterus with its appendages, and the vagina.
The size of the pelvis is determined by specialized instruments; in women, vaginal examination is an additional means of measurement. The muscles of the back and of the spinal column are attached to the pelvic bones in the back, and the abdominal muscles, in front; the muscles of the lower extremities also extend from the pelvis. The paired gluteus maximus is the largest muscle in the pelvic region. Blood is supplied to the pelvic walls and the organs within the pelvis by branches of the paired internal iliac artery. The pelvis is innervated by branches of the sacral plexus.
The most dangerous injuries to the pelvis are fractures caused by a great traumatic force, with or without a break in the continuity of the pelvic circumference. Dislocations are uncommon, but children with pelvic injuries often suffer ruptures of the ligaments as well as dislocations, such as those of the hip joint, rather than fractures. When the bones in the sacroiliac articulation and symphysis pubica are simultaneously displaced, half the pelvis is dislocated. During childbirth, a break in the symphysis pubica may take place. Fractures in the region of the cotyloid cavity may be associated with dislocation of the femur. Fractures of pelvic bones may accompany injuries to the organs within the pelvis, particularly ruptures of the bladder and urethra.
Diseases of the pelvis include hematogenous osteomyelitis, in which the ossa ilii and sacrum are usually affected, impairment of the sacroiliac articulation in brucellosis, and rheumatoid arthritis.
REFERENCESFrauchi, V. Kh. Topograficheskaia anatomiia i operativnaia khirurgiia zhivota i taza. [Kazan] 1966.
Anatomiia cheloveka. Edited by S. S. Mikhailov. Moscow, 1973.
V. F. POZHARISKII