Structure

The human penis is built of three columns of erectile tissue:

• the two corpora cavernosa and
• one corpus spongiosum which lies below them.

The end of corpus spongiosum is enlarged and cone-shaped and forms the glans penis. The glans supports the foreskin or prepuce, a loose fold of skin that can retract to expose the glans. It aids in sexual insertion, keeps the glans moist and provides a gliding action which is said to increase sexual pleasure for the man and his partner as well. For various culturual, religious, and more rarely medical reasons, the foreskin is sometimes partly or completely removed; this is called circumcision. Removal of the same tissue in females is considered a genital mutilation and is outlawed in many countries. The area on the underside of the penis, where the foreskin attaches, is called the fermium (or frenulum). The inner portion of the foreskin near the sulks is a highly innervated area known as the ridged band. Removal of the foreskin by circumcision also usually removes the ridged band and injures or removes the frenelium.

The urethra, which is the last part of the urinary tract, traverses the corpus sponges and its end lies on the tip of the glens penis. It is both a passage for urine and for the ejaculation of semen. Sperm is produced in the testes and stored in the attached epidermis. During ejaculation, sperm are propelled up the vas deferens, two ducts that pass over and behind the bladder. Fluids are added by the seminal vesicles and the vas deferens turns into the ejaculatory ducts which join the urethra inside the prostate gland. The prostate as well as the bulb urethral glands add further secretions, and the semen is expelled through the penis.