The superficial perineal compartment lies between the superficial perineal fascia and the inferior fascia of the urogenital diaphragm (perineal membrane) (Fig. 5.20). The superficial perineal fascia has a superficial and deep component. The superficial layer is relatively thin and fatty and is continuous superiorly with the superficial fatty layer of the lower abdominal wall (Camper fascia). It continues laterally as the fatty layer of the thighs. The deep layer of the superficial perineal (Colles) fascia is continuous superiorly with the deep layer of the superficial abdominal fascia (Scarpa fascia), which attaches firmly to the ischiopubic rami and ischial tuberosities. The superficial perineal compartment is continuous superiorly with the superficial fascial spaces of the anterior abdominal wall, allowing spread of blood or infection along that route. Such spread is limited laterally by the ischiopubic rami, anteriorly by the transverse ligament of the perineum, and posteriorly by the superficial transverse perineal muscle. The superficial perineal compartment includes the following:
The vestibular bulbs are 3-cm, highly vascular structures surrounding the vestibule and located under the bulbocavernosus muscle. The body of the clitoris is attached by two crura to the internal aspect of the ischiopubic rami. The crura are covered by the ischiocavernosus muscles.
The muscles of the vulva are the ischiocavernosus, the bulbocavernosus, and superficial transverse perineal. They are included in the superficial perineal compartment as follows:
Action—compresses the crura and lowers the clitoris
Insertion—posterior aspect of the clitoris; some fibers pass above the dorsal vein of the clitoris in a slinglike fashion
Action—compresses the vestibular bulb and dorsal vein of the clitoris
Action—fixes the perineal body
The vestibular glands are situated on either side of the vestibule under the posterior end of the vestibular bulb. They drain between the hymen and the labia minora. Their mucous secretion helps maintain adequate lubrication. Infection in these glands can result in an abscess.
The deep perineal compartment is a fascial space bound inferiorly by the perineal membrane and superiorly by a deep fascial layer that separates the urogenital diaphragm from the anterior recess of the ischiorectal fossa (Fig. 5.21). It is stretched across the anterior half of the pelvic outlet between the ischiopubic rami. The deep compartment may be directly continuous superiorly with the pelvic cavity (35). The posterior pubourethral ligaments, functioning as winglike elevations of the fascia ascending from the pelvic ﬂoor to the posterior aspect of the symphysis pubis, provide a point of fixation to the urethra and support the concept of the continuity of the deep perineal compartment with the pelvic cavity.
The anterior pubourethral ligaments represent a similar elevation of the inferior fascia of the urogenital diaphragm and are joined by the intermediate pubourethral ligament, with the junction between the two fascial structures arcing under the pubic symphysis (36). The urogenital diaphragm includes the sphincter urethrae (urogenital sphincter) and the deep transverse perineal (transversus vaginae) muscle.