The vagina is a hollow tube extending upward and posteriorly between the urethra and the rectum. Its upper third takes a horizontal plane and terminates in the cup-shaped fornix. The vaginal mucosa lies in transverse folds, or rugae.
At almost right angles to the vagina sits the uterus, a flattened fibromuscu-lar structure shaped like an inverted pear. The uterus has two parts: the body (corpus) and the cervix, which are joined together by the isthmus. The convex upper surface of the body is called the fundus of the uterus. The lower part of the uterus, the cervix, protrudes into the vagina, dividing the fornix into anterior, posterior, and lateral fornices.
The vaginal surface of the cervix, the ectocervix, is seen easily with the help of a speculum. At its center is a round, oval, or slitlike depression, the external os of the cervix, which marks the opening into the endocervical canal. The ectocervix is covered by epithelium of two possible types: a plushy, red columnar epithelium surrounding the os, which resembles the lining of the endocervical canal; and a shiny pink squamous epithelium continous with the vaginal lining. The boundary between these two types of epithelium is the squamocolumnar junction. In puberty, the broad band of columnar epithelium encircling the os, called ectropion, is gradually replaced by columnar pithelium. The squamocolumnar junction migrates toward the os, creating ie transformation zone. (This is the area at risk for later dysplasia, which is ampled by the Papanicolaou, or Pap, smear.)
j fallopian tube with a fanlike tip extends from each side of the uterus to-iward the ovary. The two ovaries are almond-shaped structures that vary con-
siderably in size but average about 3.5 x 2 x 1.5 cm from adulthood through menopause. The ovaries are palpable on pelvic examination in roughly half of women during the reproductive years. Normally, fallopian tubes cannot be felt. The term adnexa (a plural Latin word meaning appendages) refers to the ovaries, tubes, and supporting tissues.
The ovaries have two primary functions: the production of ova and the secretion of hormones, including estrogen, progesterone, and testosterone. Increased hormonal secretions during puberty stimulate the growth of the uterus and its endometrial lining. They enlarge the vagina and thicken its epithelium. They also stimulate the development of secondary sex characteristics, including the breasts and pubic hair.
The parietal peritoneum extends downward behind the uterus into a cul de sac called the rectouterine pouch (pouch of Douglas). You can just reach this area on rectovaginal examination.
The pelvic organs are supported by a sling of tissues composed of muscle, ligaments, and fascia, through which the urethra, vagina, and rectum all pass.
Lymphatics. Lymph from the vulva and the lower vagina drains into the inguinal nodes. Lymph from the internal genitalia, including the upper vagina, flows into the pelvic and abdominal lymph nodes, which are not palpable clinically.
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