The Anatomy of the Penis
The penis is as complex as any other part of the human body, despite a deceivingly simple appearance. Moreover, since the two functions of the penis are well-known to men and women alike, there is a tendency to think that everybody knows everything worth knowing about it.
However, there are always a few questions left unanswered or some obscure bit of information that nobody bothers to remember and which may become interesting in a certain context.
Basically, the human penis is made up of two parts: the shaft and the glans (also known as the head). The shaft is not a muscle as some have suggested. It is made of three columns of tissue, one of which continues forward to form the glans. These columns are called the Corpus Spongiosus, which forms the underside of the penis and the glans, and the Corpora Cavernosa, which are two chambers of tissue located next to each other on the upper side of the penis.
The shaft is covered in skin, while the glans supports the loosely attached fold of skin known as the foreskin. The foreskin is attached to the underside of the penis, in an area called the frenum. And, lastly, the penis is traversed from base to tip by the Urethra. This canal serves as a passage for both urine, produced in the bladder, and the sperm, produced in the testes.
Erection is achieved by filling the two Corpora Cavernosa chambers with blood. Unlike some other mammals, humans have no erectile bone and have to rely instead on engorgement with blood to reach erection.
When the erection is triggered by sexual stimulation, the arteries that bring blood to the penis dilate in order to increase blood flow. The sponge-like Corpora Cavernosa fills up with blood, which makes the penis stiff. The stiffer tissues constrict the veins that carry blood away from the penis in order to maintain the erection.
Every male baby is born with a full set of reproductive organs. However, these organs are not fully developed and remain so until the boy enters puberty.
At puberty, usually between the ages of 10 and 14, the pituitary gland starts secreting hormones that induce the testicles to produce testosterone. This is the hormone that controls all the physical and many of the psychological traits that define man.
Its presence ensures the development of bigger bones and higher muscle mass in men. It is also responsible for the increase in penis and testicles size, the apparition of pubic hair and the deeper tone of the male voice.
The penis stops growing at the end of puberty, which comes around the age of 18. However, there are many environmental factors that may delay or accelerate the onset or the end of puberty. This means that some men may experience penis growth beyond the age of 18.
A common urban myth that almost everyone has heard, is the idea that penis size is linked to the size of another body part. The most common versions of this myth focus on the size of hands, feet, nose or overall height to determine the size of the penis. Actually, there is no such link.
Although the development of the penis in the embryo is controlled by the same genes as the limbs, penis growth at puberty is entirely governed by testosterone and has nothing to do with the other parts of the body.
Some men are born with big penises. This is an undisputed fact of life whose causes are still a mystery to science. As stated above, there is no correlation between penis and body size.
Studies conducted on bats have shown that the sexual organs and the brain require large quantities of energy to develop. At some point, the developing embryo decides whether it wants a bigger brain or a bigger set of sexual organs. However, science is still at a loss to understand how the decision is made and why.