In adult women, the hymen is a membrane of varying thickness that surrounds the vaginal opening more or less completely.
Perineal body Fuseddistal segment of urethra & vagina
FIGURE 2-4 Vagina and surrounding anatomy. (Reproduced with permission from Corton MM: Anatomy. In Hofman BL, Schorge JO,
Bradshaw KD, et al (eds): Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 201o6.)
It is composed mainly of elastic and collagenous connective tissue, and both outer and inner surfaces are covered by nonkeratinized stratified squamous epithelium. he aperture of the intact hymen ranges in diameter from pinpoint to one that admits one or even two ingertips. As a rule, the hymen is torn at several sites during irst coitus. However, identical tears may form by other penetration, for example, by tampons used during menstruation. The edges of the torn tissue soon reepithelialize. In pregnant women, the hymeneal epithelium is thick and rich in glycogen. Changes produced in the hymen by childbirth are usually readily recognizable. For example, over time, the hymen transforms into several nodules of various sizes, termed hymeneal or myrtiform caruncles.
Proximal to the hymen, the vagina is a musculomembranous tube that extends to the uterus and is interposed lengthwise between the bladder and the rectum (Fig. 2-4). Anteriorly, the vagina is separated from the bladder and urethra by connective tissue-the vesicovaginal septum. Posteriorly, between the lower portion of the vagina and the rectum, similar tissues together form the rectovaginal septum. The upper fourth of the vagina is separated from the rectum by the rectouterine pouch, also called the cul-de-sac or pouch of Douglas.
Normally, the anterior and posterior walls of the vaginal lumen lie in contact, with only a slight space intervening at the lateral margins. Vaginal length varies considerably, but commonly, the anterior wall measures 6 to 8 cm, whereas the posterior vaginal wall is 7 to 10 cm. The upper end of the vaginal
Posteriorcul-de-sac of Douglas sphincter m.
External anal sphincter m.
vault is subdivided by the cervix into anterior, posterior, and two lateral fornices. Clinically, the internal pelvic organs usually can be palpated through the thin walls of these fornices.
The vaginal lining is composed of nonkeratinized stratified squamous epithelium and underlying lamina propria. In premenopausal women, this lining is thrown into numerous thin transverse ridges, known as rugae, which line the anterior and posterior vaginal walls along their length. Deep to this, a muscular layer contains smooth muscle, collagen, and elastin. Beneath this muscularis lies an adventitial layer consisting of collagen and elastin (Weber, 1997).
The vagina lacks glands. Instead, it is lubricated by a transudate that originates from the vaginal subepithelial capillary plexus and crosses the permeable epithelium (Kim, 201l). Due to increased vascularity during pregnancy, vaginal secretions are notably increased. At times, this may be confused with amnionic fluid leakage, and clinical diferentiation of these two is described in Chapter 22 (p. 435).
Mter birth-related epithelial trauma and healing, fragments of stratified epithelium occasionally are embedded beneath the vaginal surface. Similar to its native tissue, this buried epithelium continues to shed degenerated cells and keratin. As a result, epidermal inclusion cysts, which are filled with keratin debris, may form. hese are a common vaginal cyst.