| Bulboid corpuscle | |
|---|---|
 End-bulb of Krause. | |
| Details | |
| Identifiers | |
| Latin | corpuscula bulboideum |
| FMA | 83603 |
| Anatomical terminology | |
The bulboid corpuscles (end-bulbs of Krause, Krause corpuscles) are cutaneous receptors in humans and other animals.
The end-bulbs of Krause were named after the German anatomist Wilhelm Krause (1833–1910). [1] [2]
The end-bulbs of Krause were thought to be thermoreceptors, sensing cold temperatures, but in early research their function remained unknown. [3] Recently optogenetic studies revealed their role in sexual stimulation and mating behavior in mice:
"Optogenetic activation of male Krause corpuscle afferent terminals evoked penile erection, while genetic ablation of Krause corpuscles impaired intromission and ejaculation of males as well as reduced sexual receptivity of females. Thus, Krause corpuscles, which are particularly dense in the clitoris, are vibrotactile sensors crucial for normal sexual behavior." [4]
They are minute cylindrical or oval bodies, consisting of a capsule formed by the expansion of the connective-tissue sheath of a medullated fiber, and containing a soft semifluid core in which the axis-cylinder terminates either in a bulbous extremity or in a coiled-up plexiform mass.
End-bulbs are found in the conjunctiva of the eye (where they are spheroidal in shape in humans, but cylindrical in most other animals), in the mucous membrane of the lips and tongue, and in the epineurium of nerve trunks.
Krause corpuscles are found in the penis and the clitoris [5] and sometimes are referred to as genital corpuscles; [6] in these situations they have a mulberry-like appearance, being constricted by connective-tissue septa into from two to six knob-like masses.[ citation needed ]
In the synovial membranes of certain joints, e. g., those of the fingers, rounded or oval end-bulbs occur, and are designated articular end-bulbs.
In amniotes, the clitoris is a female sex organ. In humans, it is the vulva's most erogenous area and generally the primary anatomical source of female sexual pleasure. The clitoris is a complex structure, and its size and sensitivity can vary. The visible portion, the glans, of the clitoris is typically roughly the size and shape of a pea and is estimated to have at least 8,000 nerve endings.
Clitoridectomy or clitorectomy is the surgical removal, reduction, or partial removal of the clitoris. It is rarely used as a therapeutic medical procedure, such as when cancer has developed in or spread to the clitoris. Commonly, non-medical removal of the clitoris is performed during female genital mutilation.
In male human anatomy, the glans penis or penile glans, commonly referred to as the glans, 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. 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. 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.
The G-spot, also called the Gräfenberg spot, is characterized as an erogenous area of the vagina that, when stimulated, may lead to strong sexual arousal, powerful orgasms and potential female ejaculation. It is typically reported to be located 5–8 cm (2–3 in) up the front (anterior) vaginal wall between the vaginal opening and the urethra and is a sensitive area that may be part of the female prostate.
The nipple is a raised region of tissue on the surface of the breast from which, in lactating females, milk from the mammary gland leaves the body through the lactiferous ducts to nurse an infant. The milk can flow through the nipple passively, or it can be ejected by smooth muscle contractions that occur along with the ductal system. The nipple is surrounded by the areola, which is often a darker colour than the surrounding skin.
In female humans and other mammals, the clitoral hood is a fold of skin that surrounds and protects the glans of the clitoris; it also covers the external clitoral shaft, develops as part of the labia minora and is homologous with the foreskin in the male reproductive system. The clitoral hood is composed of mucocutaneous tissues; these tissues are between the mucous membrane and the skin, and they may have immunological importance because they may be a point of entry of mucosal vaccines.
An erogenous zone is an area of the human body that has heightened sensitivity, the stimulation of which may generate a sexual response such as relaxation, sexual fantasies, sexual arousal, and orgasm.
A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are innervated by sensory neurons that convert mechanical pressure into electrical signals that, in animals, are sent to the central nervous system.
The human female reproductive system is made up of the internal and external sex organs that function in the reproduction of new offspring. The reproductive system is immature at birth and develops at puberty to be able to release matured ova from the ovaries, facilitate their fertilization, and create a protective environment for the developing fetus during pregnancy. The female reproductive tract is made of several connected internal sex organs—the vagina, uterus, and fallopian tubes—and is prone to infections. The vagina allows for sexual intercourse, and is connected to the uterus at the cervix. The uterus accommodates the embryo by developing the uterine lining.
The Pacinian corpuscle is a low-threshold mechanoreceptor responsive to vibration or pressure, found in the skin and other internal organs. In the skin it is one of the four main types of cutaneous receptors.
The clitoral crura are two erectile tissue structures, which together form a "V" shape. Crus is a Latin word that means "leg". Each "leg" of the V converges on the clitoral body. At each divergent point is a corpus cavernosum. Together with the vestibular bulbs, they form the clitoral root. The crura are attached to the pubic arch, and are adjacent to the vestibular bulbs. The crura flank the urethra, urethral sponge, and vagina and extend back toward the pubis. Each clitoral crus connects to the rami of the pubis and the ischium.
In female anatomy, the vestibular bulbs, bulbs of the vestibule or clitoral bulbs are two elongated masses of erectile tissue typically described as being situated on either side of the vaginal opening. They are united to each other in front by a narrow median band. Some research indicates that they do not surround the vaginal opening, and are more closely related to the clitoris than to the vestibule. They constitute the root of the clitoris along with the crura.
The dorsal artery of the penis is a bilaterally paired terminal branch of the internal pudendal artery which passes upon the dorsum of the penis to the base of the glans penis, where it unites with its contralateral partner and supply the glans and foreskin.
The corpus cavernosum of the clitoris is one of a pair of sponge-like regions of erectile tissue that engorge with blood during an erection. This is homologous to the corpus cavernosum of the penis. The term corpora cavernosa literally means "cave-like bodies".
The perineal membrane is an anatomical term for a fibrous membrane in the perineum. The term "inferior fascia of urogenital diaphragm", used in older texts, is considered equivalent to the perineal membrane.
The development of the reproductive system is the part of embryonic growth that results in the sex organs and contributes to sexual differentiation. Due to its large overlap with development of the urinary system, the two systems are typically described together as the genitourinary system.
In human male anatomy, the radix or root of the penis is the internal and most proximal portion of the human penis that lies in the perineum. Unlike the pendulous body of the penis, which is suspended from the pubic symphysis, the root is attached to the pubic arch of the pelvis and is not visible externally. It is triradiate in form, consisting of three masses of erectile tissue; the two diverging crura, one on either side, and the median bulb of the penis or urethral bulb. Approximately one third to one half of the penis is embedded in the pelvis and can be felt through the scrotum and in the perineum.
In most terrestrial mammals, the scrotum or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin containing the external spermatic fascia, testicles, epididymides, and vasa deferentia. The scrotum will usually tighten when exposed to cold temperatures.
In mammals, the vulva comprises mostly external, visible structures of the female genitalia leading into the interior of the female reproductive tract, starting at the vaginal opening. For humans, it includes the mons pubis, labia majora, labia minora, clitoris, vestibule, urinary meatus, vaginal introitus, hymen, and openings of the vestibular glands. The folds of the outer and inner labia provide a double layer of protection for the vagina. Pelvic floor muscles support the structures of the vulva. Other muscles of the urogenital triangle also give support.
The clitoris is a female sex organ present in mammals, ostriches and other amniotes.
This article incorporates text in the public domain from page 1060 of the 20th edition of Gray's Anatomy (1918)
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