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Uterus. objectives. Identify the uterus, its normal site, shape, parts , size and position. Discuss its peritoneal covering and relations. Discuss the uterine relations. Determine the factors supporting the uterus. Discuss its blood, nerve supply and lymphatic drainage. . Uterus.
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objectives • Identify the uterus, its normal site, shape, parts, size and position. • Discuss its peritoneal covering and relations. • Discuss the uterine relations. • Determine the factors supporting the uterus. • Discuss its blood, nerve supply and lymphatic drainage.
Uterus • This is a hollow, thick-walled, pear-shaped muscular organ located between the bladder and the rectum (in non-pregnant women). • It is 7 to 8 cm long, 5 to 7 cm wide, and 2 to 3 cm thick. • The non-gravid (not pregnant) uterus usually lies in the lesser pelvis,
The uterus consists of 2 major parts: • The expanded superior 2/3 is known as the body; • The cylindrical inferior 1/3 is called the cervix (L. neck). • The uterus is usually bent anteriorly (anteflexed) between the cervix and body. • The entire uterus is normally bent or inclined anteriorly (anteverted). • It is frequently retroverted (inclined posteriorly) in older women.
Different parts of the uterine tube and the uterus. B. External os of the cervix: (above) nulliparous; (below) parous. C. Anteverted position of the uterus. D. Anteverted and anteflexed position of the uterus
The Fundus of the Uterus • The fundus of the uterus is the rounded superior part of the body. • It is located superior to the line joining the points of entrance of the uterine tubes. • The regions of the body where the uterine tubes enter are called the cornua (L. horns).
The Cervix of the Uterus • It is the cylindrical, narrow inferior part of the uterus. 1. Supravaginal part between the isthmus and the vagina. 2. Vaginal part that protrudes into the vagina and surrounds the external os of the uterus.
The Cervix of the Uterus • The supravaginal part of the cervix is separated from the bladder anteriorly by loose connective tissue and from the rectum posteriorly by the rectouterine pouch. • The cervix is mostly fibrous, with a small amount of smooth muscle and elastin.
The wall of the body of the uterus consists of three layers • The outer serous coat called the perimetrium, consists of peritoneum supported by a thin layer of connective tissue; • The middle muscular coat called the myometrium consists of smooth muscle. The myometrium increases greatly during pregnancy. The main branches of the blood vessels and nerves of the uterus are located in this layer.
The wall of the body of the uterus consists of three layers • The inner mucous coat called endometriumis firmly adherentto the underlying myometrium. • The endometrium is partly sloughed off each month during menstruation.
The Ligaments of the Uterus 1- The Round Ligament of the Uterus • The ligament extends for the lateral aspect of the uterus, passing anteriorly between the layers of the broad ligament. • They leave the abdominal cavity through the inguinal canal and insert into the labia majora.
The Ligaments of the Uterus 2- The ligament of the ovary • Externally, attaches to the uterus posteroinferior to the uterotubal junction. • These two ligaments are vestiges of the ovarian gubernaculum, related to the descent of the gonad from its developmental position on the posterior abdominal wall.
3- The Uterosacral Ligaments • Pass superiorly and slightly posteriorly from the sides of the cervix to the middle of the sacrum; they are palpable on rectal examination. The Principal Support of the Uterus • This is the pelvic floor, formed by the pelvic diaphragm. • The pelvic viscera surrounding the uterus and the visceral fascia (endopelvic fascia) bind the pelvic viscera together. • The two levator ani muscles, the two coccygeus muscles, and the muscles of the urogenital diaphragm are particularly important in supporting the uterus.
4- The Broad Ligament • This is a fold of peritoneum with mesothelium on its anterior and posterior surfaces. • It extends from the sides of the uterus to the lateral walls and floor of the pelvis. • The broad ligament holds the uterus in its normal position. • The 2 layers of the broad ligament are continuous with each other at a free edge.
4- The Broad Ligament • Laterally, the broad ligament is prolonged superiorly over the ovarian vessels as the suspensory ligament of the ovary. • The broad ligament contains extraperitoneal tissue (connective tissue and smooth muscle) called parametrium. • It gives attachment to the ovary through the Mesovarium. • The Mesosalpinx is a mesentery supporting the uterine tube.
The Relation of the Uterus • Anteriorlythe body of the uterus is separated from the urinary bladder by the vesicouterine pouch. • Here, the peritoneum is reflected from the uterus onto the posterior margin of the superior surface of the bladder. • The vesicouterine pouch is empty when the uterus is in its normal position.
The Relationships of the Uterus • Posteriorlythe body of the uterus and the supravaginal part of the cervix are separated from the sigmoid colon by a layer of peritoneum and the peritoneal cavity. • The uterus is separated from the rectum by the rectouterine pouch (of Douglas).
Laterallythe relationship of the ureter to the uterine artery is very important. • The ureter is crossed superiorly by the uterine artery at the side of the cervix.
Arterial Supply of the Uterus • This is derived mainly from the uterine arteries, which are branches of the internal iliac arteries. • They enter the broad ligaments beside the lateral parts of the fornix of the vagina, superior to the ureters. • The uterine artery divides into a large ascending branch that supplies the body of the uterus and a small descending branch that supplies the cervix and vagina.
Arterial Supply of the Uterus • The uterus is also supplied by the ovarian arteries, which are branches of the aorta. • The uterine arteries pass along the sides of the uterus within the broad ligament and then turn laterally at the entrance to the uterine tubes, where they anastomose with the ovarian arteries.
Venous Drainage of the Uterus • The uterine veinsenter the broad ligaments with the uterine arteries. • They form a uterine venous plexuson each side of the cervix and its tributaries drain into the internal iliac vein.
Lymphatic Drainage of the Uterus • The uterine lymphatic vessels follow three main routes : 1. Most vessels from the uterine fundus and superior uterine body pass along the ovarian vessels to the lumbar (caval/aortic) lymph nodes, but some vessels pass along the round ligament of the uterus to the superficial inguinal lymph nodes.
Lymphatic Drainage of the Uterus • Vessels from most of the uterine body pass within the broad ligament to the external iliac lymph nodes. • Vessels from the uterine cervix pass along the uterine vessels to the internal iliac lymph nodes and along the uterosacral ligaments to the sacral lymph nodes.
Innervation of the Uterus • The nerves of the uterus arise from the inferior hypogastric plexus, known as the uterovaginal plexus. • This lies in the broad ligament on each side of the cervix. • Parasympathetic fibersare from the pelvic splanchnic nerves (S2-4), and sympathetic fibersare from the inferior hypogastric plexus.
Innervation of the Uterus • The nerves to the cervix form a plexus in which are located small paracervical ganglia. • One of these are large and is called the uterine cervical ganglion. • The autonomic fibres of the uterovaginal plexus are mainly vasomotor. • Most the afferent fibres ascend through the inferior hypogastric plexus and enter the spinal cord via T10-12 and L1 spinal nerves.
