Emission Is the Release of Spermatozoa and Accessory Gland Fluids into the Pelvic Urethra, Whereas Ejaculation Is the Forceful Expulsion of Semen from the Urethra

Emission is the release of spermatozoa and accessory gland fluids into the pelvic urethra as a result of sympathetically mediated thoracolumbar reflex contraction of the smooth muscle in the ductus deferens and accessory glands. Ejacula­tion is the forceful expulsion of semen from the urethra and is prompted by a parasympathetically mediated sacral reflex that induces rhythmic contractions of the bulbospongiosus, ischio­cavernosus, and urethralis muscles. After ejaculation, a sacral sympathetically mediated increase in the smooth muscle tone of the cavernous spaces increases the outflow of blood, and contraction of the retractor penis muscle withdraws the penis into the prepuce.