It is often assumed that the sole function of the foreskin is to protect the glans. Does recent research support this idea?
The foreskin does protect the glans, but this is not its main function. The foreskin is designed, primarily, to provide light touch, reflex, and erogenous sensory functions. The ridged band is just as important, sexually, as the glans. The foreskin, therefore, does protect the glans but, more importantly, it is designed to protect its own, specialized, mucosal surfaces by turning them inwards, towards the glans.
How does the foreskin compare with the glans as sexual tissue?
The foreskin and the glans have similar functions. Both are designed to trigger nerve impulses that lead to erection and ejaculation. The glans detects deep pressure and movement. The foreskin detects movement through the accordion-like action of the ridged band; in addition, the outer, true skin of the foreskin has an exquisite ability to detect light touch and pin-prick. The glans lacks these abilities because it relies on the covering foreskin to provide them.
What is so special about the ridged band?
The ridged band is part of a muco-cutaneous junctional zone, so called because it lies at the junction between true skin and mucous membrane. Like all such zones, it is equipped with special sensory nerves designed to detect movement. Some junctional zones, such as the lips and eyelids, detect movement through bristle-like hairs. For obvious reasons, the foreskin lacks bristles; instead it is deeply ridged. Its ridges open and close, accordion-like, when the foreskin is stretched. This movement probably helps stimulate motion-sensitive nerve endings in the ridges. Thus the foreskin, lips and eyelids are variants of a basic structural design that differs according to location and type of mechanical stimuli encountered.
How is the foreskin stimulated?
The outside of the foreskin is sensitive to light touch. This sensitivity transmits important information on the general environment of the penis to the brain. The inside layer of the foreskin, especially the ridged band, transmits impulses to the spinal cord which, in turn, transmits impulses to the penis and to the muscle responsible for ejaculation. This is a spinal reflex and, hence, the ridged band is “reflexogenic” as well as touch-sensitive. The main stimulus to reflex activity appears to be stretching of the ridged band.
How does the foreskin interact with other parts of the penis?
The ridged band, which is mucous membrane (“mucosa”), is joined directly to the true skin of the penis. The glans, on the other hand, does not come in direct contact with true skin. This arrangement suggests that the ridged band depends for stimulation on the tugging action of penile skin during intercourse. The glans is more independent of penile skin, both functionally and physically.
What is the biological advantage of the connection between penile skin and ridged band?
This connection enables ridged band reflexes to be activated when any part of the penile skin is stretched towards the base of the penis. In other words, the connection allows activation of the ridged band “at a distance.” The glans, by contrast, is only activated by a stimulus applied to its surface. Activation of the ridged band “at a distance” might serve a useful biological function, ensuring that ejaculation takes place during, not before, full penetration.
Why is the skin of the penis muscular?
Contraction of Dartos muscle in the skin of the foreskin and penile shaft stiffens that skin during erection. Dartos muscle, therefore, solidifies the linkage between penile skin and ridged band, ensuring rapid transmission of force from one to the other. The same sheet of muscle extends into the scrotum, where its effects are well known. The distribution and function of Dartos muscle is convincing evidence of the unity of foreskin and penile shaft skin. Although all skin contains some muscle, usually attached to hair roots, sheet-like Dartos muscle is found only in the skin of the genitals.
Does the foreskin allow easy vaginal penetration and a sliding action during intercourse?
The double-layered design of the foreskin does indeed permit smooth penetration and a sliding action. The skin of the penis, including the foreskin, becomes rougher during erection. This roughness is brought about by a mechanism similar to that which raises goosebumps. The extra frictional resistance brought about in this way reduces slippage of penile skin against female tissues. The double-layering of the foreskin is designed to offset the frictional effect of “erect” penile skin and allow for easy vaginal penetration.
What determines the length of the foreskin?
When the foreskin is pulled back (retracted), the ridged band comes to rest on or near the middle of the shaft of the penis. If the foreskin is short, the ridged band lies nearer the glans. If the foreskin is long, the ridged band is deployed nearer the base of the penis, depending of course on the length of the penis. The advantages of one position over another could be debated, but the ridged band of the short foreskin might be activated before that of the long foreskin. It would be interesting to find out whether long foreskins confer a reproductive advantage.
Does the surface (epithelium) of the glans thicken and lose its sensitivity after circumcision, as many believe?
Probably not to any significant extent. There is a slight increase in the thickness of the glans epithelium due to exposure to clothing. However, it is doubtful whether this thickening would interfere with perception of deep touch or movement, which are practically the only stimuli the glans can detect. The glans is normally insensitive to light touch and pinprick; it is not the highly sensitive tissue that most men believe it to be.
How do ridged band and glans compare for size?
If it were flattened out, the corrugated ridged band would probably occupy about the same surface area as the glans. Area is more important than mass because “genital corpuscles” are concentrated in surface tissue, just beneath the surface epithelium of a mucous membrane.
Does removal of the foreskin affect the function of the penis as a whole?
This area has not been researched in depth but there is some evidence that circumcision does affect the mechanics of intercourse. Circumcised men, for instance, may be more dependent on direct glans stimulation than are intact men. This is one area of research that requires a much greater input from sexually active men. First of all, we need a working hypothesis we can test.
The Circumcision Information and Resource Pages are a not-for-profit educational resource and library. IntactiWiki hosts this website but is not responsible for the content of this site. CIRP makes documents available without charge, for informational purposes only. The contents of this site are not intended to replace the professional medical or legal advice of a licensed practitioner.
© CIRP.org 1996-2023 | Please visit our sponsor and host: IntactiWiki.