ABSTRACT
Apart from its important role in maintaining urinary continence, prostatic and bladder neck sympathetic innervation is also essential for ejaculation. Erectile function, by contrast, is subserved by parasympathetic fibers, which pass in the so-called neurovascular bundles of Walsh lying posterolateral to the prostate; these fibers are capable of producing vasodilatation within the corpora cavernosa9 (Figure 7). In this periprostatic location, these nerves are vulnerable to injury during either radical prostatectomy or radical cystoprostatectomy performed for the surgical excision of urological malignancy. At the time of ejaculation, a synchronized sequence of sympathetically induced contractions develops in the vasa deferentia, seminal vesicles and prostatic smooth muscle itself. This activity delivers a mixture of fluid from the seminal vesicles, semen from the vasa and fluid containing PSA from the prostate into the prostatic urethra, via openings in the verumontanum. Tight closure of the bladder neck then creates a ‘pressure chamber’ within the prostate such that, when reflex relaxation of the external sphincter occurs in conjunction with pulsatile contractions of the bulbocavernous muscles, antegrade ejaculation results (Figure 8).
