In
malehuman anatomy, the glans penis or penile glans,[2] commonly referred to as the glans, (/ɡlænz/; from
Latinglans meaning "acorn")[3] is the bulbous structure at the
distal end of the
human penis that is the human male's most sensitive
erogenous zone and primary
anatomical source of
sexual pleasure.[4][5] The glans penis is present in the male
reproductive organs of
humans and most other
mammals where it may appear smooth, spiny, elongated or divided.[6] It is externally lined with
mucosal tissue, which creates a smooth texture and glossy appearance. In humans, the glans is located over the distal ends of the
corpora cavernosa and is a continuation of the
corpus spongiosum of the penis. At the summit appears the
urinary meatus and at the base forms the
corona glandis. An elastic band of tissue, known as the
frenulum, runs on its ventral surface. In men who are not
circumcised, it is completely or partially covered by a fold of skin called the
foreskin. In adults, the foreskin can generally be retracted over and past the glans manually or sometimes automatically during an
erection.[7]
The glans is more commonly known as the "head" or the "tip" of the penis, and colloquially referred to in
British English and
Irish English as the "bellend".
Structure
The glans penis is a body of spongy
erectile tissue that is moulded on the rounded ends of the two
corpora cavernosa penis,[10] extending farther on their upper than on their lower surfaces. It is the expanded cap of the
corpus spongiosum,[11] a sponge-like region that surrounds the male
urethra within the penis maintaining it as a viable channel for
ejaculation.[12] The glans is covered by a
stratified squamous epithelium and a dense layer of
connective tissue equivalent to the
dermis of typical skin.[13] The papillary layer of the dermis blends into the dense connective tissue forming the
tunica albuginea of the corpus spongiosum behind the glans.[13] The external lining with
mucosal tissue is responsible for its typical smooth texture and appearance.
The increase of
arterial flow during
erection fills the erectile tissue with blood causing the glans to grow in size and sensitivity.[14] While the penis is rigid when erect, the glans itself remains slightly softer.[15] The soft cushiony texture of the glans absorbs impact during rigorous instances of copulation.[16] The proportional size of the glans penis can vary among males. While the shape of the glans is typically acorn-like, in some men it might be wider in circumference than the shaft, giving the penis a mushroom-like appearance, while in others it might be narrower and more akin to a probe in shape. Some researchers have suggested that the glans has evolved to become acorn-, mushroom- or cone-shaped so that during copulation it acts to remove any semen still there from previous sex partners, but this is not supported when looking at primate relatives who have different mating behaviors.[17][18]
At the summit of the glans is the slit-like vertical external urethral orifice, called the
urinary meatus, through which urine,
semen and
pre-ejaculatory fluid exit the penis. The circumference of the base of the glans forms a rounded projecting border, the
corona glandis, overhanging a deep retroglandular
groove known as the coronal sulcus. Behind the corona is the neck of the penis, which separates the glans and the penile shaft. Ventrally, the two glans wings merge on the midline forming the
septum glandis and a triangle or a V-shaped area under it. The
frenulum is the highly
vascularized elastic band of tissue located on the underside of the glans that connects the foreskin to the head of the penis. The frenulum is supple enough to allow the retraction of the foreskin over the glans and pull it back when the erection is gone.[19] In flaccid state, it tightens to narrow the foreskin opening.[20]
Innervation
The glans and the frenulum are
innervated by the bilateral
dorsal nerve of the penis and the
perineal nerve, both divisions of the
pudendal nerve.[21] Branches of the dorsal nerve extend through the glans ventrolaterally displaying a three-dimensional innervation pattern.[21][22] The main branches form smaller bundles of nerves that expand outwards into the tissue of the glans.[21] The rich innervation of the glans penis reveals its function as a primary anatomical source of male sexual pleasure.[5][22][23] Yang & Bradley argue; "the distinct pattern of innervation of the glans emphasizes its role as a sensory structure".[5] While Yang & Bradley's (1998) report "showed no areas in the glans to be more densely innervated than others.",[5] Halata & Munger (1986) report that the density of several nerve terminals is greatest in the corona glandis.[13]
Halata & Spathe (1997) reported; "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 (
mechanoreceptors typically found in thick
glabrous skin) are not present".[24] The genital end bulbs, that are present throughout the glans, are most numerous in the corona and near the frenulum.[13] Simple, Pacinian and Ruffinian corpuscles are identified predominantly in the corona glandis. The most numerous nerve terminals are free nerve endings present in almost every
dermal papilla of the glans, as well as scattered throughout the deeper
dermis.[13]
Blood supply
The glans penis receives blood from the
internal pudental artery through its branch, the
dorsal artery of the penis, which also supplies the foreskin, and the
penile shaft.[25] Behind the
corona, the terminal branches of the dorsal arteries
anastomose with the axial arteries through perforating branches before they end in the glans.[26] Branches of the dorsal artery curve around each side of the distal shaft to enter the glans and the frenulum ventrally.[27] Venous drainage of the penis begins at the base of the glans. Small tributaries deriving from the corona form a venous plexus at the neck of the penis, known as the retro-coronal, or retro-
balanic, plexus.[28] Smaller paired venules run into the frenulum and the glans from its ventral surface.[29] The deep dorsal vein, one of the two
dorsal veins of the penis, serves as a common vessel receiving blood drained from the glans and the two
corpora cavernosa through the circumflex veins that surround them.[30][28]
Foreskin
The glans is completely or partially covered by a double-layered fold of skin, known as the
foreskin. In adults, glans exposure can be easily achieved by manual retraction of the foreskin or sometimes automatically during
erection. The degree of automatic foreskin retraction varies considerably depending on the foreskin length. The foreskin can be characterized as long when the preputial orifice extends beyond the glans during erection or medium when the orifice is located around the meatus.[31] The primary purpose of the foreskin is considered to be the covering of the glans and the
urinary meatus,[32][33] while also maintaining the
mucosa in a moist environment.[34]
Foreskin rectractability gradually increases with age. In
infancy the foreskin is fused to the glans,[35] it remains non retractable in early
childhood and it continues to be tight during
preadolescence.[36] The skin begins to loosen up significantly during
puberty allowing the glans to be completely exposed when needed. By the age of eighteen most boys will have a fully retractable foreskin.[37]
In some cases, for
cultural,
medical, or
prophylactic reasons some men undergo
circumcision or were circumcised as infants, a procedure where the foreskin is partially or completely removed from the penis.[20] The glans of circumcised men remains fully exposed and dry. Several studies have suggested the glans is generally equally sensitive in both circumcised and uncircumcised penises,[38][39][40] though physical changes do occur, including
keratinazation of the glans.[41]
Although the sex of the infant is
determined from the moment of
conception,[8] the complete external differentiation of the organs begins about eight or nine weeks after conception.[44] Some sources state that the process will be completed by the twelfth week,[45][46] while others state that it is clearly evident by the thirteenth week and that the sex organs are fully developed by the sixteenth week.[9]
Both the penis and clitoris develop from the same
tissues that become the glans and
shaft of the penis and this shared embryonic origin makes these two organs
homologous (different versions of the same structure).[9][47] In the
female fetus the absence of testosterone will stop the growth of the phallus causing the tubercle to shrink and form the clitoris. In the
male fetus the presence of a Y chromosome leads to the development of the
testes, which secrete a large amount of hormones called androgens. These hormones will cause the
masculinization of the phenotypically indifferent organs.[8] When exposed to testosterone, the genital tubercle elongates to form the
penis. By fusion of the
urogenital folds – elongated spindle-shaped structures that contribute to the formation of the
urethral groove on the belly aspect of the genital tubercle – the
urogenital sinus closes completely to form the
spongy urethra and the labioscrotal swellings unite to form the
scrotum.[48][9] The secretion of testosterone during this phase plays a decisive role in the final shaping of the penis. After birth, testosterone levels drop significantly until
puberty.
Clinical significance
The
epithelium of the glans penis consists of
mucosal tissue. Birley et al. report that excessive washing with soap may dry the mucous membrane which covers the glans penis and cause non-specific
dermatitis. The condition is described as an inflammation of the skin, often caused by an irritating substance or a
contact allergy. Sensitivity to chemicals in certain products can cause an allergic reaction, including irritation,
itching and
rash.[49]
Inflammation of the glans penis is known as
balanitis. It is a treatable condition that occurs in about 3–11% of males (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. It has many causes, including irritation or infection with a wide variety of
pathogens. Symptoms of balanitis may appear suddenly or develop gradually. They might include pain, irritation, redness or red patches on the glans penis. 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.[50]
The
meatus (opening) of the urethra located at the tip of the glans might become subject to
meatal stenosis, a condition mostly seen as a late complication of circumcision. It occurs in about 2–20% of circumcised boys[51][52] and it is rarely seen in uncircumcised men.[53] It is characterized by a narrowing of the meatus, which might cause sudden or often urges to urinate and burning during the process.[53]
For some individuals who experience difficulty in achieving full glanular engorgement of glans penis, they may be diagnosed with soft glans syndrome (
glans insufficiency syndrome). It is often undiagnosed in the general population due to the lack of a standardized nomenclature.[54][55]
Other animals
Mammals
Carnivores
Male
felids are able to
urinate backwards by curving the tip of the glans penis backward.[56][57] In cats, the glans penis is covered with spines.
Penile spines also occur on the glans of male and female
spotted hyenas.[56] In male dogs the glans penis is smooth and consists of two parts called the bulbus glandis and pars longa glandis.[58] 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.[59]
Rodents
The glans penis of the
marsh rice rat is long and robust,[60] averaging 7.3 mm (0.29 in) long and 4.6 mm (0.18 in) broad.[61]Winkelmann's mouse can most readily be distinguished from its close relatives by its partially corrugated glans penis.[62] 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.[63] The glans penis of a male
cape ground squirrel is large with a prominent
baculum.[64]
The shape of the glans varies among different
marsupial species.[75][76][77] In most marsupials, the glans is divided, but male
macropods have an undivided glans penis.[6]
^Olausson, Håkan; Wessberg, Johan; Morrison, India (2016). Affective Touch and the Neurophysiology of CT Afferents.
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abcdYang, C. C.; W.E. Bradley (July 1998). "Neuroanatomy of the penile portion of the human dorsal nerve of the penis". British Journal of Urology. 82 (1): 109–13.
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^Keenan-Lindsay, Lisa; Sams, Cheryl; O'Connor, Constance; Perry, Shannon; Hockenberry, Marilyn; Leonard Lowdermilk, Deitra; Wilson, David (December 17, 2021). Maternal Child Nursing Care in Canada.
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^Hsu, Geng-Long; Lu, Hsiu-Chen (2018-01-01),
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^HSU, G‐L., et al. "The distribution of elastic fibrous elements within the human penis." BJU International 73.5 (1994): 566-571.
^Sloane, Ethel (2002). Biology of Women. Cengage Learning.
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^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.
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