A 39-year-old man is unable to expel the last drops of urine from the urethra at the end of micturition because of paralysis of the external urethral sphincter and bulbospongiosus muscles. This condition may occur as a result of injury to which of the following nervous structures?
(A) Pelvic plexus
(B) Prostatic plexus
© Pudendal nerve
(D) Pelvic splanchnic nerve
(E) Sacral splanchnic nerve
The answer is C. The perineal branch of the pudendal nerve supplies the external urethral
sphincter and bulbospongiosus muscles in the male. All other nervous structures do not
supply skeletal muscles but supply smooth muscles in the perineal and pelvic organs. The
pelvic and prostatic plexuses contain both sympathetic and parasympathetic nerve fi bers.