The pelvis is a part of the skeleton that belongs to the lower extremity belt and consists of two pelvic bones, a sacrum and a coccyx (Fig.). The bone-ligament base of the pelvis and hip joints serves as a support for the trunk.
Distinguish between a large and small pelvis. The large pelvis is limited: in front by soft tissues of the anterior abdominal wall, behind - by the spine , from the sides - by the wings of the iliac bones; small pelvis: in front - pubic (bones) bones, behind - sacrum and coccyx, and laterally - with sciatic bones.
The pelvic bone consists of three bones: iliac, ischial and pubic, connected to the lateral sections of the sacrum (sacroiliac joint) and to each other (lonnoe connection). The lower part of the sacrum is connected to the coccyx, forming a slow-moving joint, strengthened in front and behind by ligaments. On the back of the ischium there are two notches that are overlapped by the ligaments, forming a large and small ischium hole. The musculoskeletal structures present in the pelvis: the anterior superior and inferior awns, the iliac crest, the lumbar joint, etc. serve as identification points used for orientation in this area and measurement of the pelvis. In newborns there is some flattening of the iliac bone, a mismatch in size and shape of the acetabulum and the femoral head.
Sexual features of the pelvis - see Female pelvis .
The large pelvis contains organs of the lower abdominal cavity (small and large intestine); small pelvis - bladder, rectum and internal genital organs (in women - the uterus and its appendages, in men - the prostate gland , seminal vesicles , part of the vas deferens).The
The peritoneum covering the organs of the small pelvis, when moving from one organ to another, forms pockets: in men it is vesical-rectum, in women it is vesicoureteral and rectal-uterine, which in case of pathology can be filled with exudate or blood. In the subperitoneal space (between the peritoneum and the fascia) lie fiber, enveloping the vessels, nerves and organs of the small pelvis.
Within the pelvis are located: ilio-lumbar, internal blocking, pear-shaped muscles that originate from the pelvic bones and attach to the thigh; muscle, lifting the anus, sphincter of the anus and the coccygeal muscle. The external group of pelvic muscles include: external blocking, large, medium and small gluteal, upper and lower twin muscles. The muscle that raises the anus is threaded into the walls of the vagina, rectum, and attached to the coccyx.
In the area of the locking hole and the membrane, both inside and outside, internal and external inhibitory muscles begin to attach to the thigh in the region of the fossa. From the lateral surface of the II, III and IV sacral vertebrae and the sacroiliac joint, the pear-shaped muscle passes through a large sciatic hole and is attached to the apex of the large trochanter. This muscle, passing through this hole, forms two cracks: over-and subgranular; through the first of them go the upper gluteal vessels and nerve, and through the second (podrushevidnuyu) - the lower glute vessels, the eponymous nerve, sciatic nerve, etc. Through the small sciatic hole from the pelvis into the perineum penetrate the vascular vessels and nerve.
Exit from the small pelvis is limited to sciatic tubercles, sacro-tuberous ligaments and is closed by muscles (raising the anus and the coccygeal) and the fascia that form the pelvic floor, or the pelvic diaphragm. The angle between the pubic bones is made by the urogenital diaphragm formed by two muscles - the sphincter of the urethra and the deep transverse muscle of the perineum. Through the urogenital diaphragm pass the urethra and the vagina , and through the pelvic diaphragm - the rectum .
The fascia of the pelvis is a continuation of the fascia lining the abdominal cavity; she has two sheets: visceral and parietal. The first forms fascial cases for the organs of the small pelvis (bladder, rectum), and the second - lining the walls of the pelvis.
The blood supply of the pelvis and its organs is provided by the branches of the internal iliac artery. The veins that accompany the arteries form venous plexuses, the blood from which is poured into the internal iliac vein, and then into the lower hollow and partly into the portal vein. Lymph outflow occurs along the external iliac artery and vein, internal iliac vessels and along the anterior surface of the sacrum. The sacral plexus is located on the anterior surface of the sacrum and pear-shaped muscle, the branches of which, together with the branches of the lumbar, coccygeal plexus and pelvic part of the autonomic nervous system , innervate the muscles and organs of the small pelvis.