|male sexual organs|
3. Corpus cavernosa
6. Urethral opening
7. 8. Corpus spongiosum
|Latin||GraySubject = 262|
|Dorlands/Elsevier||[http://www.mercksource.com/pp/us/cns/cns_hl_dorlands_split.jsp?pg=/ppdocs/us/common/dorlands/dorland/nine/000953185.htm 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. When the penis is flaccid it is sometimes wholly 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.
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.
The epithelium of the glans penis is mucocutaneous tissue. Birley et al. report that excessive washing with soap may dry the mucous membrane that covers the glans penis and cause non-specific dermatitis.
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. 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.
The glans penis is the expanded cap of the corpus spongiosum. It is moulded on the rounded ends of the Corpores 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. 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. In males who have been circumcised, but have not undergone restoration, 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. Several studies have suggested that the glans is equally sensitive in circumcised and uncircumcised males, while others have reported that it is more sensitive in uncircumcised males (the interpretation of one of these studies is disputed).
Halata & Munger (1986) report that the density of genital corpuscles is greatest in the corona glandis, while Yang & Bradley (1998) report that their study "showed no areas in the glans to be more densely innervated than others."
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."
Yang & Bradley argue that "The distinct pattern of innervation of the glans emphasizes the role of the glans as a sensory structure".