Perineum LO3

3. Review the structures of the superficial perineal space/pouch of the urogenital triangle.

The superficial perineal space is deep to the superficial fascia (subcutaneous), and superficial to the perineal membrane. Contained within the superficial perineal space are the erectile bodies and associated musculature. There are two sets of erectile bodies: corpus spongiosum and corpus cavernosum. Within close association with the portions of the erectile tissues within the superficial perineal space are muscles: bulbospongiosus & ischiocavernosus mm. These muscles apply pressure to erectile tissue.

Female erectile bodies and associated muscles:

The corpus spongiosum manifests as the bulbs of the vestibule (vestibular bulbs), masses of erectile tissue flanking the vestibule of the vagina and attached to the perineal membrane. The vestibular bulbs are united anteriorly by a slight commissure, which is associated with the body of the clitoris. The vestibular bulbs are served by the arteries of the bulb (of vestibule). The vestibular bulbs are covered by the bulbospongiosus mm.

The corpus cavernosum manifest as the clitoris, a mass of erectile tissue important for sexual response. Most of the clitoris consists of paired elements of erectile tissue called corpora cavernosa (sing. = corpus cavernosum). The corpora cavernosa of clitoris consist of the crura of clitoris (which run adjacent to the inferior margins of the ischiopubic rami) and the body of clitoris (which consists of the paired, yet separated termini of the corpora cavernosa). The body of clitoris (often referred to as the shaft) may be palpated through the skin, and the glans (of) clitoris is comprised of corpus spongiosum, and sits atop the inferior portion of the body of clitoris. The glans clitoris is densely covered in sensory receptors and free nerve endings. The erectile tissues of the clitoris are served by the deep arteries of the clitoris. The superficial tissues of the glans clitoris are served by the dorsal arteries of the clitoris. The crura of clitoris are covered by the ischiocavernosus mm.

Male erectile bodies and associated muscles:

The corpus spongiosum manifests as a midline mass proximally (within the deep perineal space) as the bulb of the penis, continuing distally (surrounding the urethra in the body of the penis), before terminating as the erectile tissue of the glans penis. The corpus spongiosum is served by the arteries of the bulb (of penis). The bulb of the penis is covered by the bulbospongiosus mm.

The corpus cavernosum manifest as the crura of the penis proximally, along the ischipubic rami (within the deep perineal space), continuing into the body of the penis as dorsally paired masses of erectile tissue. The corpus cavernosa are served by the deep arteries of the penis. The superficial tissues of the body of the penis are served by the dorsal arteries of the penis. The crura of the penis are covered by the ischiocavernosus mm.

The superficial and deep spaces of the urogenital triangle are variously traversed by branches of the pudendal n. and internal pudendal a. (the dominant neurovascular supply to the perineum). Pudendal is derived from the Latin pudere, ‘to be ashamed.’ [As anatomists, we contend that no structure is inherently shameful, so chin up!]