Pelvic Floor And Perineum (A&I)

Question 1

External anal sphincter

Answer 1

Action: constricts anal canal during peristalsis, resisting defecation; supports and flexes perineal body.pelvic floor
Innervation: inferior anal nerve, branch of pudendal nerve (S2-S4)

Question 2

Bulbospongiosus

Answer 2

Action: supports and flexes perineal body/pelvic floor; male- compresses bulb of penis to ex[el last drops of urine/semen, assists erection by compressing outflow via deep perineal vein and by pushing blood from bulb of penis into body of penis; female- “sphincter” of vagina, assists in erection of clitoris, compresses greater vestibular gland
Innervation: muscular (deep) branch of perineal nerve, branch of pudendal nerves (S2-S4)

Question 3

Ishciocavernosus

Answer 3

Action: maintains erection of penis or clitoris by compressing outflow veins and pushing blood from root of penis or clitoris into body
Innervation: muscular (deep) branch of perineal nerve, branch of pudendal nerve

Question 4

Superficial transverse perineal

Answer 4

Action: supports and fixes perineal body to support abdominal pelvic viscera and resisting increased intra-abdominal pressure
Innervation: muscular (deep) branch of perineal nerve, branch of pudendal nerve (S2-S4), dorsal nerve of penis or clitoris, terminal branch of pudendal nerve (S2-S4)