The penis is the external male organ associated with both sex and urination. It is composed of three columns of erectile tissue and relies on the engorgement of blood to reach the erect state.
The erectile tissues are divided into two groups named the "corpus spongiosum" and "corpus cavernosum." The corpus spongiosum is the single column that lies on the underside of the penis. The other two colums, the corpora cavernosa, are positioned next to each other on the upper side of the penis. The glans penis, located at the end of the corpus spongiosum is the part that is enlarged and cone-shaped. The glans supports the foreskin (also called prepuce), which is the loose fold of skin that can retract to expose the glans. The area on the underside of the penis, where the foreskin is attached, is called the frenum.
The urethra, which is the final destination of the urinary tract, traverses the corpus spongiosum. It's opening, known as the "meatus", lies on the tip of the glans penis. The urethra serves as both a passage for urine and for the ejaculation of semen. Sperm is produced within the testes and stored in the attached epididymis.
During ejaculation, sperm is propelled up the vas deferens, the 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 and the bulbourethral glands add further secretions, and the resulting semen is expelled through the penis.
The last feature of the penis is called the "raphe." This is the visible ridge between the lateral halves of the penis. It is found on the underside of the penis and runs from the meatus (opening of the urethra) across the scrotum and to the perineum (area between scrotum and anus).
Posted by PRS
Friday, September 23rd, 2005