Glans penis

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Glans penis
Glans Penis of A Human.jpg
Glans penis (dorsal view)
Anat09IMG 0034.jpg
Glans penis (ventral view)
Latin Glans penis
Gray's p.1248
Artery Urethral artery
Dorlands
/Elsevier
Glans penis
Male anatomy
Male anatomy.png
The male anatomy showing the location of the glans penis
Gray's p.1248

In male human anatomy, the glans penis (or simply glans, /ɡlænz/)[1] is the sensitive bulbous structure at the distal end of the penis. The glans is anatomically homologous to the clitoral glans of the human female. Typically, the glans is completely or partially covered by the foreskin, except in men who have been circumcised, though the foreskin can generally be retracted over and past the glans.

The glans is more commonly known as the "head of the penis". The medical name comes from the Latin word glans ('acorn') and penis ('of the penis') – the Latin genitive of this word has the same form as the nominative.

Medical considerations[edit]

The meatus (opening) of the urethra is located 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, or meatal stenosis.[2]

The epithelium of the glans penis is mucocutaneous tissue.[3] Birley et al. report that excessive washing with soap may dry the mucous membrane that covers the glans penis and cause non-specific dermatitis.[4]

Inflammation of the glans penis is known as balanitis. It occurs in 3–11% of males, and up to 35% of diabetic males. Edwards reported that it is generally more common in males who have poor hygiene habits or have not been circumcised.[5] 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.[5]

Anatomical details[edit]

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.

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 a 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 males who are not circumcised.[12][13]

Halata & Munger (1986) report that the density of genital corpuscles is greatest in the corona glandis,[14] 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."[3]

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

Evolutionary significance[edit]

It has been suggested that the unique and unusual shape of the glans in circumcised 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 impregnating the female.[15] 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.

In non-human animals[edit]

The glans of a fossa's penis extends about halfway down the shaft and is spiny except at the tip. In comparison, the glans of felids is short and spiny, while that of viverrids is smooth and long.[16] Male felids urinate backwards by curving the tip of the glans penis backward.[17][18]

The shape of the glans varies among different marsupial species.[19][20][21][22][further explanation needed]

The glans penis of the marsh rice rat is long and robust,[23] averaging 7.3 mm (0.29 in) long and 4.6 mm (0.18 in) broad.[24]

In Thomasomys ucucha the glans penis is rounded, short, and small and is superficially divided into left and right halves by a trough at the top and a ridge at the bottom. Most of the glans is covered with spines, except for an area near the tip.[25]

Winkelmann's mouse can most readily be distinguished from its close relatives by its partially corrugated glans penis.[26]

When erect, the glans of a horse's penis increases by 3 to 4 times. The urethra opens within the urethral fossa, a small pouch at the distal end of the glans.[27] Unlike the human glans, the glans of a horse's penis extends backwards on its shaft.[28][29][30][31][32][33][34][35][36]

Males of Racey's pipistrelle bat have a narrow, egg-shaped glans penis.[37]

The glans penis of a male cape ground squirrel is large with a prominent baculum.[38]

See also[edit]

References[edit]

  1. ^ OED 2nd edition, 1989.
  2. ^ 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. Retrieved 2006-07-07. 
  3. ^ 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. Retrieved 2006-07-07. 
  4. ^ Birley, H. D.; M .M. Walker, G. A. Luzzi, R. Bell, D. Taylor-Robinson, M. Byrne & A. M. Renton (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. 
  5. ^ a b Edwards, Sarah (June 1996). "Balanitis and balanoposthitis: a review". Genitourinary Medicine 72 (3): 155–9. PMC 1195642. PMID 8707315. 
  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. 
  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. 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 [1])
  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. 
  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. 
  12. ^ Sorrells, Morris L.; Snyder, James L.; Reiss, Mark D.; Eden, Christopher; Milos, Marilyn F.; Wilcox, Norma; Van Howe, Robert S. (April 2007). "Fine-touch pressure thresholds in the adult penis". British Journal of Urology International 99 (4): 864–869. doi:10.1111/j.1464-410X.2006.06685.x. PMID 17378847. 
  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. ^ 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. 
  15. ^ 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. 
  16. ^ Köhncke, M.; Leonhardt, K. (1986). "Cryptoprocta ferox" (PDF). Mammalian Species (254): 1–5. Retrieved 19 May 2010. 
  17. ^ Reena Mathur (2010). Animal Behaviour 3/e. Rastogi Publications. ISBN 978-81-7133-747-7. Retrieved 10 February 2013. 
  18. ^ R. F. Ewer (1973). The Carnivores. Cornell University Press. pp. 116–. ISBN 978-0-8014-8493-3. Retrieved 8 February 2013. 
  19. ^ Renfree, Marilyn; Hugh Tyndale-Biscoe (1987-01-30). Reproductive Physiology of Marsupials. Cambridge University Press. ISBN 9780521337922. Retrieved 5 May 2013. 
  20. ^ Australian Mammal Society (December 1978). Australian Mammal Society. Australian Mammal Society. pp. 73–. Retrieved 25 December 2012. 
  21. ^ Wilfred Hudson Osgood; Charles Judson Herrick (1921). A monographic study of the American marsupial, Caēnolestes .... University of Chicago. pp. 64–. Retrieved 25 December 2012. 
  22. ^ The Urologic and Cutaneous Review. Urologic & Cutaneous Press. 1920. pp. 677–. Retrieved 25 December 2012. 
  23. ^ Hooper and Musser, 1964, p. 13
  24. ^ Hooper and Musser, 1964, table 1
  25. ^ Voss, 2003, p. 11
  26. ^ Bradley, R.D. & Schmidley, D.J. (1987). "The glans penes and bacula in Latin American taxa of the Peromyscus boylii group". Journal of Mammalogy 68 (3): 595–615. JSTOR 1381595. 
  27. ^ "The Stallion: Breeding Soundness Examination & Reproductive Anatomy". University of Wisconsin-Madison. Archived from the original on 2007-07-16. Retrieved 7 July 2007. 
  28. ^ Mating Males: An Evolutionary Perspective on Mammalian Reproduction. Cambridge University Press. 30 June 2012. ISBN 978-1-107-00001-8. Retrieved 5 May 2013. 
  29. ^ McCurnin's Clinical Textbook for Veterinary Technicians - Joanna M Bassert, Dennis M McCurnin - Google Boeken. Books.google.com. Retrieved 2013-08-16. 
  30. ^ Horseman's Veterinary Encyclopedia, Revised and Updated - Equine Research - Google Boeken. Books.google.com. 2005-07-01. Retrieved 2013-08-16. 
  31. ^ Equine Clinical Medicine, Surgery and Reproduction - Graham Munroe BVSc (Hons) PhD Cert EO DESM Dip ECVS FRCVS, Scott Weese DVM DVSc DipACVIM - Google Boeken. Books.google.com. 2011-03-15. Retrieved 2013-08-16. 
  32. ^ Veterinary Anatomy of Domestic Mammals: Textbook and Colour Atlas - Google Boeken. Books.google.com. Retrieved 2013-08-16. 
  33. ^ Horse Conformation: Structure, Soundness, and Performance - Equine Research - Google Boeken. Books.google.com. Retrieved 2013-08-16. 
  34. ^ The Horse - Google Boeken. Books.google.com. Retrieved 2013-08-16. 
  35. ^ Comparative Reproductive Biology - Heide Schatten, Gheorghe M. Constantinescu - Google Boeken. Books.google.com. 2008-03-21. Retrieved 2013-08-16. 
  36. ^ Equine Reproduction - Google Boeken. Books.google.com. Retrieved 2013-08-16. 
  37. ^ Bates et al., 2006, pp. 306–307
  38. ^ Skurski, D., J. Waterman. 2005. "Xerus inauris", Mammalian Species 781:1-4.

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