Glans penis

Glans penis
Anterior view of the glans penis of an uncircumcised penis
Latin	Glans penis
Gray's	subject #262 1248
Artery	Urethral artery
Dorlands/Elsevier	Glans penis

The glans penis (or simply glans) is the sensitive bulbous structure at the distal end of the penis. The glans penis is anatomically homologous to the clitoral glans of the female. It is sometimes fully or partially covered by the foreskin, except in men who have been fully circumcised.

The glans is also commonly referred to as the "head of the penis", while common British slang terms include "helmet," "knob end" and "bell end", all referring to its distinctive shape. The medical name comes from Latin glans "acorn" + penis "of the penis" – the Latin genitive of this word has the same form as the nominative.

Medical considerations

The meatus (opening) of the urethra is at the tip of the glans penis. In circumcised infants, the foreskin no longer protects the meatal area of the glans; consequently, when wearing diapers, there may be greater risk of developing meatitis, meatal ulceration, and meatal stenosis.^[1]

The epithelium of the glans penis is mucocutaneous tissue.^[2] Birley et al. report that excessive washing with soap may dry the mucous membrane that covers the glans penis and cause non-specific dermatitis.^[3]

Inflammation of the glans penis is known as balanitis. It occurs in 3–11% of males, and up to 35% of diabetic males. It is more common among uncircumcised males.^[4] It has many causes, including irritation, or infection with a wide variety of pathogens. Careful identification of the cause with the aid of patient history, physical examination, swabs and cultures, and biopsy are essential in order to determine the proper treatment.^[4]

Anatomical details

The glans penis is the expanded cap of the corpus spongiosum. It is moulded on the rounded ends of the Corpora cavernosa penis, extending farther on their upper than on their lower surfaces. At the summit of the glans is the slit-like vertical external urethral orifice. The circumference of the base of the glans forms a rounded projecting border, the corona glandis, overhanging a deep retroglandular sulcus (the coronal sulcus), behind which is the neck of the penis. The proportional size of the glans penis can vary greatly. On some penises it is much wider in circumference than the shaft, giving the penis a mushroom-like appearance, and on others it is narrower and more akin to a probe in shape. It has been suggested that the unique and unusual shape of the glans in humans has evolved to serve the function of "scooping" any remnant semen deposited by other rival males out of the deeper part of the vagina of a female who may have recently copulated, and thereby decreasing the chance of the rival male from impregnating the female.^[5] Other theorists^[who?] suggest that its distinctive shape evolved to heighten the sexual pleasure experienced by the female during vaginal intercourse. In this theory, the glans increases friction and tension at the mouth of the vagina by its additional girth and the dilating properties of its probe-like shape.

The foreskin maintains the mucosa in a moist environment.^[6] In males who have been circumcised, the glans is permanently exposed and dry. Szabo and Short found that the glans of the circumcised penis does not develop a thicker keratinization layer.^[7] Several studies have suggested that the glans is equally sensitive in circumcised and uncircumcised males,^{[8][9][10][11]} while others have reported that it is more sensitive in uncircumcised males^[12][13] (the interpretation of one of these studies is disputed^[14]).

Halata & Munger (1986) report that the density of genital corpuscles is greatest in the corona glandis,^[15] while Yang & Bradley (1998) report that their study "showed no areas in the glans to be more densely innervated than others."^[13]

Halata & Spathe (1997) reported that "the glans penis contains a predominance of free nerve endings, numerous genital end bulbs and rarely Pacinian and Ruffinian corpuscles. Merkel nerve endings and Meissner's corpuscles are not present."^[2]

Yang & Bradley argue that "The distinct pattern of innervation of the glans emphasizes the role of the glans as a sensory structure".^[13]

See also

• Clitoris
• Corpus cavernosum penis
• Foreskin
• Frenulum of prepuce of penis
• Hirsuties papillaris genitalis

References

1. ^ Freud, Paul (August 1947). "The ulcerated urethral meatus in male children". The Journal of Pediatrics 31 (2): 131–41. doi:10.1016/S0022-3476(47)80098-8. PMID 20256409. http://www.cirp.org/library/complications/freud1/. Retrieved 2006-07-07. 
2. ^ ^{a b} Halata, Zdenek; A. Spaethe (1997). "Sensory innervation of the human penis". Advances in experimental medicine and biology. Advances in Experimental Medicine and Biology 424: 265–6. doi:10.1007/978-1-4615-5913-9_48. ISBN 978-0-306-45696-1. PMID 9361804. http://www.cirp.org/library/anatomy/halata2/. Retrieved 2006-07-07. 
3. ^ Birley, H. D.; M .M. Walker, G. A. Luzzi, R. Bell, D. Taylor-Robinson, M. Byrne, A. M. Renton & Tomas Nelson (October 1993). "Clinical features and management of recurrent balanitis; association with atopy and genital washing". Genitourinary Medicine 69 (5): 400–3. PMC 1195128. PMID 8244363. http://www.cirp.org/library/disease/balanitis/birley/. 
4. ^ ^{a b} Edwards, Sarah (June 1996). "Balanitis and balanoposthitis: a review". Genitourinary Medicine 72 (3): 155–9. PMC 1195642. PMID 8707315. http://www.cirp.org/library/disease/balanitis/edwards1/. 
5. ^ Gallup, Gordon; Rebecca L. Burch, Mary L. Zappieri, Rizwan A. Parvez, Malinda L. Stockwell, Jennifer A. Davis (July 2003). "The human penis as a semen displacement device". Evolution and Human Behavior 24 (4): 277–289. doi:10.1016/S1090-5138(03)00016-3. http://www.journals.elsevierhealth.com/periodicals/ens/article/PIIS1090513803000163/abstract. 
6. ^ Prakash, Satya; Raghuram Rao, K. Venkatesan & S. Ramakrishnan (July 1982). "Sub-Preputial Wetness--Its Nature". Annals of National Medical Science (India) 18 (3): 109–112. http://www.cirp.org/library/anatomy/prakash/. 
7. ^ Szabo, Robert; Roger V. Short (June 2000). "How does male circumcision protect against HIV infection?". British Medical Journal 320 (7249): 1592–4. doi:10.1136/bmj.320.7249.1592. PMC 1127372. PMID 10845974. http://bmj.bmjjournals.com/cgi/content/full/320/7249/1592. Retrieved 2006-07-07. 
8. ^ Masters, William H.; Virginia E. Johnson (1966). Human Sexual Response. Boston: Little, Brown & Co. pp. 189–91. ISBN 0-316-54987-8.  (excerpt accessible here)
9. ^ Bleustein, Clifford B.; James D. Fogarty, Haftan Eckholdt, Joseph C. Arezzo and Arnold Melman (April 2005). "Effect of neonatal circumcision on penile neurologic sensation". Urology 65 (4): 773–7. doi:10.1016/j.urology.2004.11.007. PMID 15833526. 
10. ^ Bleustein, Clifford B.; Haftan Eckholdt, Joseph C. Arezzo and Arnold Melman (April 26-May 1, 2003). "Effects of Circumcision on Male Penile Sensitivity". American Urological Association 98th Annual Meeting. Chicago, Illinois. http://www.circs.org/library/bleustein/. 
11. ^ Payne, Kimberley; Thaler, Lea; Kukkonen, Tuuli; Carrier, Serge; and Binik, Yitzchak (May 2007). "Sensation and Sexual Arousal in Circumcised and Uncircumcised Men". Journal of sexual medicine 4 (3): 667–674. doi:10.1111/j.1743-6109.2007.00471.x. PMID 17419812. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1743-6109.2007.00471.x. 
12. ^ Sorrells (April 2007). "Fine-touch pressure thresholds in the adult penis". British Journal of Urology International 99 (4): 864–869. http://www3.interscience.wiley.com/cgi-bin/fulltext/118508429/PDFSTART. 
13. ^ ^{a b c} Yang, DM; Lin H, Zhang B, Guo W (April 2008). "Circumcision affects glans penis vibration perception threshold". Zhonghua Nan Ke Xue 14 (4): 328–330. PMID 18481425. 
14. ^ Waskett, Jake H.; Brian J. Morris (May 2007). "Fine touch pressure thresholds in the adult penis". BJU International 99 (6): 1551–1552. doi:10.1111/j.1464-410X.2007.06970_6.x. PMID 17537227. http://www3.interscience.wiley.com/cgi-bin/fulltext/118508593/HTMLSTART. 
15. ^ Halata, Zdenek; Bryce L. Munger (April 1986). "The neuroanatomical basis for the protopathic sensibility of the human glans penis". Brain Research 371 (2): 205–30. doi:10.1016/0006-8993(86)90357-4. PMID 3697758. 

External links

• SUNY Labs 42:07-0102 - "The Male Perineum and the Penis: The Corpus Spongiosum and Corpora Cavernosa"
• SUNY Labs 44:06-0101 - "The Male Pelvis: The Urethra"