Surgical anatomy

CHAPTER 1 Surgical anatomy

The Ovary

The size and appearance of the ovaries depend on both age and the stage of the menstrual cycle. In the young adult, they are almond shaped, solid and white in colour, 3 cm long, 1.5 cm wide and approximately 1 cm thick. The long axis is normally vertical before childbirth; after this, there is a wide range of variation, presumably due to considerable displacement in the first pregnancy.

The ovary is the only intra-abdominal structure not to be covered by peritoneum. Each ovary is attached to the cornu of the uterus by the ovarian ligament, and at the hilum to the broad ligament by the mesovarium, which contains its supply of vessels and nerves. Laterally, each is attached to the suspensory ligament of the ovary with folds of peritoneum which become continuous with that over the psoas major.

The Fallopian Tube

The uterine or fallopian tubes are two oviducts originating at the cornu of the uterus which travel a rather tortuous course along the upper margins of the broad ligament. They are approximately 10 cm in length and end in the peritoneal cavity close to the ovary. This abdominal opening is situated at the end of a trumpet-shaped lateral portion of tube, the infundibulum. This opening is fringed by a number of petal-like processes, the fimbriae, which closely embrace the tubal end of the ovary. This fimbriated end has an important role in fertility.

Medial to the infundibulum is the ampulla which is thin walled and tortuous, and comprises at least half of the length of the tube. The medial third of the tube, the isthmus, is relatively straight. The tube has narrowed at this point, from approximately 3 mm at the abdominal opening to 1–2 mm. The final centimetre, the interstitial portion, is within the uterine wall.

The Uterus

The uterus is shaped like an inverted pear, tapering inferiorly to the cervix and, in the non-pregnant state, is situated entirely within the lesser pelvis. It is hollow and has thick muscular walls. Its maximal external dimensions are approximately 9 cm long, 6 cm wide and 4 cm thick. The upper expanded part of the uterus is termed the ‘body’ or ‘corpus’. The area of insertion of each fallopian tube is termed the ‘cornu’ and that part of the body above the cornu, the ‘fundus’. The uterus tapers to a small central constricted area, the isthmus, and below this is the cervix, which projects obliquely into the vagina and can be divided into vaginal and supravaginal portions (Figure 1.4).

The cavity of the uterus has the shape of an inverted triangle when sectioned coronally; the fallopian tubes open at the upper lateral angles (Figure 1.5). The lumen is apposed anteroposteriorly. The constriction at the isthmus where the corpus joins the cervix is the anatomical internal os.

The Vagina

The vagina is a fibromuscular tube which extends posterosuperiorly from the vestibule to the uterine cervix. It is longer in its posterior wall (approximately 9 cm) than anteriorly (approximately 7.5 cm). The vaginal walls are normally in contact, except superiorly, at the vault, where they are separated by the cervix. The vault of the vagina is divided into four fornices: posterior, anterior and two lateral. These increase in depth posteriorly. The mid-vagina is a transverse slit and the lower portion has an H-shape in transverse section.

The Vulva

The female external genitalia, commonly referred to as the ‘vulva’, include the mons pubis, the labia majora and minora, the vestibule, the clitoris and the greater vestibular glands (Figure 1.6).

Jun 4, 2016 | Posted by in GYNECOLOGY | Comments Off on Surgical anatomy

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