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CHAPTER 1  Surgical Anatomy of the Female Pelvis

numerous apocrine sweat glands, along with the normal eccrine sweat glands. The former structures undergo change with the menstrual cycle, having increased secre- tory activity in the premenstrual period. They can become chronically infected, as in hidradenitis suppurativa, or neoplastically enlarged, as in hidradenomas, both of which may require surgical therapy. The eccrine sweat glands in the vulvar skin rarely present abnormalities, but on occasion form palpable masses as syringomas. The subcutaneous tissue of the labia majora is simi- lar in composition to that of the abdominal wall. It con- sists of lobules of fat interlaced with connective tissue septa. Although there are no well-defined layers in the subcutaneous tissue, regional variations in the relative quantity of fat and fibrous tissue exist. The superficial region of this tissue, where fat predominates, is the fatty layer, as it is on the abdomen. In this region, there is a continuation of fat from the anterior abdominal wall that contains smooth muscle and the termination of the round ligament of the uterus; this tissue is called a finger-shaped process of fat. In the deeper layers of the vulva, there is less fat, and the interlacing fibrous connective tissue septa are much more evident than those in the fatty layer. As it is in the abdomen, this more fibrous layer is called the membra- nous layer (previously Colles fascia) and is similar to the membranous layer (Scarpa fascia) on the abdomen. The membranous layer attachments or the attachments of the membranous layer to other structures have clinical signif- icance. The interlacing fibrous septa of the subcutaneous tissue attach laterally to the ischiopubic rami and fuse posteriorly with the posterior edge of the perineal mem- brane (previously urogenital diaphragm). Anteriorly, however, there is no connection to the pubic rami, and this permits communication between the area deep to this layer and the abdominal wall. These fibrous attach- ments to the ischiopubic rami and the posterior aspect of the perineal membrane limit the spread of hematomas or infection deep to the membranous layer posterolaterally but allow spread into the abdomen. This clinical obser- vation has led to the consideration of the membranous layer as a separate entity from the superficial fatty layer, which lacks these connections. Spread of hematomas or infection from the subcutaneous layer of the abdomen to the corresponding layer of the perineum is also pos- sible. Extravasation of carbon dioxide into the subcu- taneous layer, as can occur during laparoscopy (either with accidental trocar displacement or with lengthy procedures), can lead to subcutaneous emphysema that extends from the subcutaneous tissue of the abdominal wall to the subcutaneous layer of the perineum. Superficial Compartment The space between the superficial layer of investing fascia of perineal muscles and perineal membrane, which contains the clitoris, crura, vestibular bulbs,

TABLE 1.2 Layers and Pouches of the Anterior Triangle of the Perineum Skin Subcutaneous perineal pouch (compartment, space) Fatty layer (Camper fascia) Membranous layer (Colles fascia) Superficial pouch (compartment, space) Superficial layer of investing fascia of perineal muscles (inferior boundary)

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Clitoris and its crura Bulb of the vestibule Greater vestibular (Bartholin) gland ischiocavernosus muscle Bulbospongiosus muscle Superficial transverse perineal muscle

Deep perineal pouch (compartment, space)  Perineal membrane (inferior boundary)  External urethral sphincter (sphincter urethrae)  Compressor urethrae  Sphincter urethrovaginalis

associated with dyspareunia or pain in these settings, the labia minora can be surgically reduced. Among others, complications such as hypoesthesia and paresthesias may develop following labial reduction procedures, given the vast sensory innervation to these structures. Moreover, chronic dermatologic diseases such as lichen sclerosus may lead to significant atrophy or disappearance of the labia minora. Surgical procedures that involve removal of the prepuce or adjacent skin and underlying connec- tive tissue may lead to injury of the dorsal nerve of the clitoris. The path of this nerve will be discussed later with other terminal pudendal nerve branches. In the posterolateral aspect of the vestibule, the duct of the greater vestibular (Bartholin) gland can be seen 3 to 4 mm outside the hymen or hymenal caruncles at the hymenal ring. The lesser vestibular gland openings are found along a line extending anteriorly from this point, parallel to the hymenal ring and extending toward the external urethral orifice. More anteriorly, the urethra protrudes slightly beyond the surrounding vestibular skin, anterior to the vagina and posterior to the clitoris. Its orifice is flanked on either side by two small folds. The openings of the most distal of the paraurethral glands, often called Skene ducts, open into the inner aspect of these folds and can be seen as small, punctate openings when the external urethral orifice is exposed. Within the skin of the vulva are specialized glands that can become enlarged and thereby require surgical removal. The holocrine sebaceous glands are associated with hair shafts in the labia majora; in the labia minora, they are freestanding. They lie close to the surface, which explains their easy recognition with minimal enlargement. In addition, lateral to the introitus and anus, there are

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