PENIS OF THE HUMAN MALE
Observe the different anatomical features of human male genitalia.
The penis is a sensitive copulatory organ of the male oh higher vertebrates important to reproduction and urination and to sexual pleasure. At its tip is the glans of the penis, which contains the urethral opening, through which urine passes and evacuates from the body.
The structure of the penis has a ridge that separates the glans from the body of the penis which is called the corona (Latin for “crown”). The glans and the corona of the penis are the most sensitive parts of the male genitalia. The glans of the penis is covered with a foreskin (prepuce) unless the man has been circumcised, in which case the foreskin has been surgically removed. The area on the underside of the penis, where the foreskin is attached, is called the frenum (or frenulum).
The human penis is made up of three cylinders of tissue that run parallel to the urethra: two corpora cavernosa lie next to each other on the dorsal side and one corpus spongiosum lies between them on the ventral side. During sexual arousal, these tissues become engorged with blood and expand in size, causing the penis to enlarge and become erect.
The enlarged and bulbous-shaped end of the corpus spongiosum forms the glans penis, which supports the foreskin or prepuce, a loose fold of skin that in adults can retract to expose the glans.
The urethra, which is the last part of the urinary tract, traverses the corpus spongiosum, and its opening, known as the meatus which lies on the tip of the glans penis. It is a passage both for urine and for the ejaculation of semen. Sperm are produced in the testes and stored in the attached epididymis. 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 bulbourethral glands add further secretions, and the semen is expelled through the penis.
The raphe is the visible ridge between the lateral halves of the penis, found on the ventral or underside of the penis, running from the meatus (opening of the urethra) across the scrotum to the perineum (area between scrotum and anus).
The human penis differs from those of most other mammals, as it has no baculum, or erectile bone, and instead relies entirely on engorgement with blood to reach its erect state. It cannot be withdrawn into the groin, and the human penis is slightly larger than average in the animal kingdom in proportion to body mass.