Foreskin

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The foreskin covering the head of the penis.

The foreskin, also called the prepuce (from Latin: prae = in front, putium = penis) is the protective sheath of flesh, which covers the glans, or head of the penis. (Greek: balanos = acorn, Latin: (pl) glandes (pen[i]um) = acorn [of the penis)]). It can be thought of as two portions; the portion of the foreskin that enfolds the glans, beginning at the coronal sulcus is called the "posthe," whereas the visually defining, tapered, fleshy, nipple-like portion of the foreskin that advances past the end of the glans is called the "acroposthion",[1][2][3] which is also known as the "overhang."

The skin of the penis is continuous with the foreskin, where it begins to form a cylindrical double layer of tissue consisting of the outer foreskin, which tapers at the acroposthion, whereupon it inverts into itself to become the inner foreskin, which consists of mucous membrane. At the tip of the acroposthion lies a mucocutaneous junction, where the skin of the outer foreskin transitions into the mucosa of the inner foreskin. Both the surface of the glans and the inner foreskin consist of mucous membrane, forming what is called the preputial space. The preputial sphincter functions as the the "drawstring" of the acroposthion, which is formed of a temperature sensitive smooth muscle sheath called the dartos muscle.

Within the preputial space, the inner foreskin is attached to the underside of the glans by a web-like membrane called the frenulum (Latin: fraenum = bridle]). The inner surface of the foreskin consists of two zones, 'ridged' and 'smooth'. The first, a transversely ridged band of mucosa 10-15 mm wide, lies along the mucocutaneous junction, forming the outer surface of the tip of the foreskin. In the dorsal midline, the 'ridged band' lies above the level of the adjacent 'smooth' mucosa and merges smoothly, on either side, with the frenulum an the underside of the glans. When magnified, the ridged mucosa has a pebbled or coral-like appearance.[4]

Upon erection, the foreskin may retract and unroll of itself into a single layered cylinder, but not necessarily, and can usually be retracted manually. Unretracted, the adult 'ridged band' usually lies flat against the glans; retracted, the 'ridged band' is everted onto the shaft of the penis. The remainder of the preputial lining between the 'ridged band' and the glans is smooth and lax. Complex touch-sensitive nerve endings, called Meissner's corpuscles, were found in these ridges. The ridged band is primarily sensory tissue, and rolling over the corona of the glans, provides primary sexual stimulation.

Retraction of the Foreskin

A human penis before and after retraction of the foreskin.

In adult men, the foreskin can usually be retracted to expose the glans with ease. In some cases, the foreskin is tight, retracting with difficulty, while in other cases, it does not retract at all. A condition where the foreskin has trouble retracting, if at all, is often called phimosis (Greek: muzzling), though this diagnosis may be erroneous. (Please see article on phimosis.)

The rare condition of difficulty in retracting the foreskin in adult men must not be confused with the natural state of the penis in neonates and pre-pubecent boys. In newborns and young children, the foreskin is adhered to the glans by means of a membrane called synechia, also known as the balano-preputial membrane or balano-preputial lamina and will not retract.[5] Forcibly retracting the foreskin of a child can cause damage to a child's penis. (Please see article on forced retraction.)

For more on foreskin retraction, please see the article on the Retraction of the Foreskin.

Importance in Sexual Intercourse

”The prepuce is a common anatomical structure of the male and female external genitalia of all human and non-human primates; it has been present in primates for at least 65 million years, and is likely to be over 100 million years old, based on it commonality as an anatomical feature in mammals”. Christopher j. Cold, M.D., and John R. Taylor, M.D. [6]

In mammals, it is known that the male prepuce is important for normal copulatory function[7]. The neuroanatomy of the prepuce forms a complex sensory platform that is important for normal sexual behavior[8]. In the human penis, the prepuce is known to have ten times as many corpuscular sensory receptors as the glans penis[9]. Surgical removal of the prepuce disturbs normal copulatory behavior in male mammals,[10][11] and similarly alters sexual behavior in humans.[12][13]


References

  1. Hodges FM. Phimosis in antiquity. World J Urol 1999;17(3):133-6.
  2. Hodges FM. .The Ideal Prepuce in Ancient Greece and Rome: Male Genital Aesthetics and Their Relation to Lipodermos, Circumcision, Foreskin Restoration, and the Kynodesme. Bull. Hist. Med., 2001 Fall; 75(3): 377-378.
  3. Translation adapted from Rufus of Ephesus, Des noms des parties du corps humain 102, in Oeuvres de Rufus d'Éphèse, ed. Charles Daremberg and Charles Émile Ruelle (Paris: L'Imprimerie Nationale, 1879), p. 146.
  4. Taylor JR, Lockwood AP, Taylor AJ. The prepuce: specialized mucosa of the penis and its loss to circumcision. Br J Urol 1996;77:291-5.
  5. Gairdner D. The fate of the foreskin: a study of circumcision. Br Med J 1949;2:1433-7.
  6. Cold CJ, Taylor JR. The prepuce. BJU Int 1999 Jan;83:34-44. [here, p.34]
  7. Cold, Christopher; McGrath, Kenneth (1999). "Anatomy and histology of the penile and clitoral prepuce in primates". Male and female circumcision: medical, legal, and ethical considerations in pediatric practice. New York. ISBN 0306461315. http://www.cirp.org/library/anatomy/cold-mcgrath/. 
  8. Taylor, J.R.; A.P. Lockwood and A.J. Taylor (1996-2). "The prepuce: Specialized mucosa of the penis and its loss to circumcision". British Journal of Urology International 77: 291-95. PMID 8800902. http://www.cirp.org/library/anatomy/taylor/. 
  9. Cold, C; Tarara R. (1997). "Penile and clitoral prepuce mucocutaneous receptors in macaca mulatta". Vet Pathol 34 (506). 
  10. Desrochers, A; St. Jean G, Anderson DE. (1986-1996). "Surgical management of preputial injuries in bulls: 51 cases". Can Vet J 1995 (36): 553-6. 
  11. Lumia, AR; Sachs BD, Meisel RL (August 1979). "Sexual reflexes in male rats: restoration of ejaculation following suppression by penile sheath removal". Physiology & Behavior 23 (2): 273-7. 
  12. Laumann, EO; Masi CM, Zuckerman EW. (April 2, 1997). "Circumcision in the United States: prevalence, prophylactic effects,and sexual practice.". Journal Of The American Medical Association 277 (13): 1052-7. http://www.cirp.org/library/general/laumann/. 
  13. Money, J; Davison J (1983). "Adult penile circumcision: erotosexual and cosmetic sequelae". The Journal of Sex Research 19: 298-92. http://www.cirp.org/library/complications/money/. 
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