The human anus from Latin anus meaning "ring", "circle"   is the external opening of the rectum. Two sphincters control the exit of feces from the body during an act of defecationwhich is the primary function of the anus.
These are the internal anal sphincter and the external anal sphincterwhich are circular muscles that normally maintain Muscle ebony anal of the orifice and which relaxes as required by normal physiological functioning.
The inner sphincter is involuntary and the outer is voluntary.
It is located behind the perineum which is located behind the vagina in females and Muscle ebony anal the scrotum in males.
With anal sexthe anus can play a role in sexuality. Attitudes towards anal sex vary and it is illegal in some countries.
The anus is also the site of potential infections and other conditions, including cancer. The anus is the final component of the gastrointestinal tractand directly continues from the rectum.
The anus passes through the pelvic floor. The anus is surrounded by muscles. The top and bottom of the anus are surrounded by the internal and external anal sphincterstwo muscular rings which control defecation. The anus is surrounded in its length by folds called anal valves, which converge at a line known as the pectinate line. This represents Muscle ebony anal point of transition between the hindgut and the ectoderm in the embryo.
Below this point, the mucosa of the internal anus becomes skin. The anus receives blood from the inferior rectal artery and innervation from the inferior rectal nerveswhich branch from the pudendal nerve.
The pseudostratified columnar epithelium of the gastrointestinal tract transitions to stratified squamous epithelium at the pectinate line. The stratified squamous epithelium gradually accumulates sebaceous and apocrine glands. During pubertyas testosterone triggers androgenic hair growth on the body, pubic hair begins to appear around the anus. Although initially sparse, it fills out by the end of
Muscle ebony anal, if not earlier.
However, in some genetic populations androgenic hair is less common. Intra-rectal pressure builds as the rectum fills with feces, pushing the feces against the walls of the anal canal.
Contractions of abdominal and pelvic floor muscles can create intra-abdominal pressure which further increases intra-rectal pressure. The internal anal sphincter an involuntary muscle responds to the pressure by relaxing, thus allowing the Muscle ebony anal to enter the canal.
The rectum shortens as feces are pushed into the anal canal and peristaltic waves push "Muscle ebony anal" feces out of the rectum. Relaxation of the internal and external anal sphincters allows the feces to exit from the anus, finally, as the levator ani muscles pull the anus up over the exiting feces. Example of a Grade IV hemorrhoidone that protrudes out of the anus.
In psychologythe Freudian term anal fixation is used. The anus has a relatively high concentration of nerve endings and can be an erogenous zonewhich can make anal intercourse pleasurable if performed properly.
The pudendal nerve that branches to supply the external anal sphincter also branches to the dorsal nerve of the clitoris and the dorsal nerve of the penis. Sigmund Freud 's theory of psychosexual developmentfor example, described an anal stagehypothesizing that toddlers derive pleasure from retaining and expelling feces.
This is the source of the term " anal-retentive " and the derived informal term "anal". In addition to nerve endings, pleasure from anal intercourse may be aided by the close proximity between the anus and the prostate for males, and vaginaclitoral legs and anal area for females. This is because of indirect stimulation of the prostate and vagina or clitoral legs.
Anal stretching or fisting is pleasurable for some, but it poses a more serious threat of damage due to the deliberate stretching of the anal and
Muscle ebony anal tissues; its injuries include anal sphincter lacerations and rectal and sigmoid colon rectosigmoid perforation, which might result in death. Anal intercourse is sometimes referred to as sodomy or buggeryand is considered taboo in a number of legal systems. It has been, and in some jurisdictions continues to be, a
Muscle ebony anal carrying severe punishment.
To prevent diseases of the anus [ citation needed ] and to promote general hygiene, humans often clean Muscle ebony anal exterior of the anus after emptying the bowels. A rinse with water from a bidet or a wipe with toilet paper is often used for this purpose, though anal cleansing practices vary greatly between cultures.
Shaving, trimming, depilatory hair removalor Brazilian waxing can clear the perineum of hair.
Anal bleaching is a process in which the anus and perineum, which may darken after puberty depending on individual genetics, is lightened for a more youthful appearance. True anal piercing is rare because it may interfere with the function of the anus.
However, surface piercings of the perineum are easier Muscle ebony anal care for and much more common. The posterior aspect of the rectum and anus exposed by removing the lower part of the sacrum and the coccyx. From Wikipedia, the free encyclopedia. It is not to Muscle ebony anal confused with Bunghole. The anus of a female left, with prominent perineal raphe and a male right.
Example of Anal warts. Original from the University of Michigan: Original from Oxford University: Archived from the original on June 13, Retrieved July 23, Gray's anatomy for students.
The Orgasm Answer Guide.
Retrieved January 20, From Cells to Society. Retrieved September 17, Retrieved November 6, Retrieved August 19, Warren; Carol Rinkleib Ellison . Houghton Mifflin Original from the University of Virginia. Many men find anal intercourse more exciting than penile-vaginal intercourse because the anal opening is usually smaller and Muscle ebony anal than the vagina. Probably the forbidden aspect of anal intercourse also makes it more exciting for some people.
Miletich; Tia Laura Lindstrom An Introduction to the Work of a Medical Examiner: From Death Scene to Autopsy Suite. Retrieved September 15, Human systems and organs. Fibrous joint Cartilaginous joint Synovial joint. Skin Subcutaneous tissue Breast Mammary gland. Myeloid Myeloid immune system Lymphoid Lymphoid immune system. Genitourinary system Kidney Ureter Bladder Urethra. Organs anatomy category Organs anatomy portal. Anatomy of the gastrointestinal tractexcluding the Muscle ebony anal. Muscles Spaces peripharyngeal retropharyngeal parapharyngeal retrovisceral danger prevertebral Pterygomandibular raphe Pharyngeal raphe Buccopharyngeal fascia Pharyngobasilar fascia Piriform sinus.
Sphincters upper lower glands. Suspensory muscle Major duodenal papilla Minor duodenal papilla Duodenojejunal flexure Brunner's glands. Ileocecal valve Peyer's patches Microfold cell. Ascending colon Hepatic flexure Transverse colon Splenic flexure Descending colon Sigmoid colon Continuous taenia coli haustra epiploic appendix.