Pelvic Cavity LO5
5. Review the vulva and associated structures.
External genitalia are located in the urogenital triangle of the perineum, a diamond-shaped region of the external pelvis that will be discussed in further detail in the following session. The pelvic wall is an inferior continuation of the abdominal wall. Of particular interest is the continuation of the layers superficial fascia: a superficial fatty (Camper's) fascia and deep membranous (Scarpa's) fascia.
The vulva (female external genitalia) is inclusive of:
- mons pubis
- labia majora
- labia minora
- vestibule of the vagina
- vestibular bulbs
- greater vestibular (Bartholin’s) glands
Anterior (and superficial) to the pubic symphysis, the mons pubis is a mound of subcutaneous tissue and skin with dense hair anterosuperiorly adjacent to the labia majora.
The labia majora (singular = labium majus) are protuberant cutaneous folds forming the lateral-most borders of the vulva. The labia majora connect the mons pubis posteriorly to the perineum. The labia majora converge anteriorly at the mons pubis to form the anterior commissure. Posteriorly, the labia do not converge, as they end in the skin of the perineum. Between the posterior termini of the labia majora, a ridge of skin, the posterior commissure, sits superficial to the perineal body.
Medial and parallel to the labia majora, the labia minora (singular = labium minus) extend posteriorly from the clitoris to encircle the vestibule. The anterior region of each labium minus diverges to form two structures: anteriorly (superficial to the clitoris) the prepuce, and posteriorly the frenulum of the clitoris. Labia minora surround the vestibule, the medial cavity that contains the external urethral meatus (the final anatomical point of the urine conduction pathway), the vaginal orifice (the external opening of the vagina), and the meatuses of the greater vestibular (Bartholin's) glands. The greater vestibular glands are associated with the posterior margin of each bulb of the vestibule (located at 5 & 7 o’clock with respect to the vaginal orifice). The ducts from the greater vestibular glands empty into the vestibule, as these glands play an important role in lubricating this area. Greater vestibular gland ducts may become blocked, thus resulting in a Bartholin cyst. Such cysts are typically painless, but if infected, they can be painful and form an abscess.
The glans clitoris (also known as the glans of clitoris, the glans, or colloquially - albeit incompletely - as the clitoris) is nestled beneath the prepuce of clitoris and supported by the frenulum of clitoris (both are of the labia minora). The clitoris is a richly vascularized and innervated (particularly the glans) structure that is an important mediator of sexual response.