At birth, the cervix and corpus are about equal in size; in adult women, the corpus has grown to two to three times the size of the cervix. The position of the uterus in relation to other pelvic structures is variable and is generally described in terms of positioning—anterior, midposition, or posterior; ﬂexion; and version. Flexion is the angle between the long axis of the uterine corpus and the cervix, whereas version is the angle of the junction of the uterus with the upper vagina. Occasionally, abnormal positioning may occur secondary to associated pelvic pathology, such as endometriosis or adhesions.
The uterine corpus is divided into several different regions. The area where the endocervical canal opens into the endometrial cavity is known as the isthmus or lower uterine segment. On each side of the upper uterine body, a funnel-shaped area receives the insertion of the fallopian tubes and is called the uterine cornu; the uterus above this area is the fundus.
The endometrial cavity is triangular in shape and represents the mucosal surface of the uterine corpus. The epithelium is columnar and gland forming with a specialized stroma. It undergoes cyclic structural and functional change during the reproductive years, with regular shedding of the superficial endometrium and regeneration from the basal layer.
The muscular layer of the uterus, the myometrium, consists of interlacing smooth muscle fibers and ranges in thickness from 1.5 to 2.5 cm. Some outer fibers are continuous with those of the tube and round ligament.
Peritoneum covers most of the corpus of the uterus and the posterior cervix and is known as the serosa. Laterally, the broad ligament, a double layer of peritoneum covering the neurovascular supply to the uterus, inserts into the cervix and corpus. Anteriorly, the bladder lies over the isthmic and cervical region of the uterus.
Blood Supply The blood supply to the uterus is the uterine artery, which anastomoses with the ovarian and vaginal arteries.
Innervation The nerve supply to the uterus is the uterovaginal plexus.
Fallopian Tubes The fallopian tubes and ovaries collectively are referred to as the adnexa. The fallopian tubes are paired hollow structures representing the proximal unfused ends of the m¨ullerian duct. They vary in length from 7 to 12 cm, and their function includes ovum pickup, provision of physical environment for conception, and transport and nourishment of the fertilized ovum.
The tubes are divided into several regions: 1.
Interstitial—narrowest portion of the tube, lies within the uterine wall and forms the tubal ostia at the endometrial cavity.
2.
Isthmus—narrow segment closest to the uterine wall.
3.
Ampulla—larger diameter segment lateral to the isthmus.
4.
Fimbria (infundibulum)—funnel-shaped abdominal ostia of the tubes, opening into the peritoneal cavity; this opening is fringed with numerous fingerlike projections that provide a wide surface for ovum pickup. The fimbria ovarica is a connection between the end of the tube and ovary, bringing the two closer.
The tubal mucosa is ciliated columnar epithelium, which becomes progressively more architecturally complex as the fimbriated end is approached. The muscularis consists of an inner circular and outer longitudinal layer of smooth muscle. The tube is covered by peritoneum and, through its mesentery (mesosalpinx), which is situated dorsal to the round ligament, is connected to the upper margin of the broad ligament.
Blood Supply The vascular supply to the fallopian tubes is the uterine and ovarian arteries.
Innervation The innervation to the fallopian tubes is the uterovaginal plexus and the ovarian plexus.