Innervation

• Erection

  • Erection of the penis is controleed by the parasympathetic nervous system via the pelvic splanchnic nerves S2-4, which dilate blood vessels supplying the erectile tissue. This engorges the corpora cavernosa and corpus spongiosum with blood; compresses the veins, which impedes venous return; and causes a full erection. The erection of the penis is also maintained by the somatic nervous system via the perineal branch of the pudendal nerve, which contracts the bulbospongiosus muscles and ischiocavernosus muscles. This compresses the erectile tissue of the bulb of the penis and the crura of the penis and helps to maintain the erection.

• Secretion

  • Secretion from the seminal vesciles, bulbourethral glands of Cowper, and prostate gland is controlled by the parasympathetic nervous system via the pelvic splanchnic nerves (S2-4), which stimulate the secretory activity of these glands.

• Emission

  • Emission from the penis is controlled by the sympathetic nervous system via the L3 and L4 lumber splanchnic nerves and the sacral splanchnic nerves, which contracts the smooth muscle of the tail region of the epididymis, ductus deferens, seminal vesicle, and prostate gland, thus promoting movement of sperm and fluid; and contracts the internal urethral sphincter (ie smooth muscle), thus preventing reflux of sperm and fluid into the urinary bladder.

• Ejaculation

  • Ejaculation from the penis is controlled by the somatic nervous system via the pudendal nerve, which contracts the bulbospongiosus muscle (ie skeletal muscle) to propel sperm and fluid and relaxes the sphincter urethrae muscle located within the deep perineal space (ie skeletal muscle; also called the external urethral sphincter).