In anatomy, the anus (from Latin ānus "ring, anus") is the external opening of the rectum. Closure is controlled by sphincter muscles. Feces are expelled from the body through the anus during the act of defecation, which is the primary function of the anus. Most animals — from simple worms to elephants and humans — have a tubular gut, with a mouth at one end and an anus at the other.
The anus plays a role in sexuality, though attitudes towards anal sex vary and it is even illegal in some countries. The anus is also the site of potential infections and other conditions including cancer. The subject is often considered a taboo part of the body, and is known by a large number of usually vulgar slang terms.
Role in sexuality
Main article: Anal sex
The anus has a relatively high concentration of nerve endings and is an erogenous zone. Sigmund Freud's theory of psychosexual development, for example, described an anal stage, hypothesizing that toddlers derive pleasure from retaining and expelling feces. This is the source of the term "anal" and the derived, derogatory vulgarism "anal-retentive."
Anal intercourse can be pleasurable for both the insertive partner and the receptive partner. For the receptive partner, pleasure from anal intercourse is also thought to be related to the shared wall between the rectum and the vagina (for females) as well as the G-spot or prostate (for males). For the insertive partner, the tightness of the anus is often said to be a source of pleasure in penetrative anal sex.
Anal intercourse, sometimes referred to as sodomy or buggery, is a human sexual activity, but is considered taboo in a number of moral systems, and it has been, and in some jurisdictions continues to be, a crime carrying severe punishment.
Anal stretching can stimulate the nerves around the anus and can be considered pleasurable. Care must be taken to maintain elasticity.
Lubricant is widely regarded as a neccessity in perfoming anal sex.
The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long. At its commencement its caliber is similar to that of the sigmoid colon, but near its termination it is dilated, forming the rectal ampulla.
Role in human defecation
The rectum ampulla acts as a temporary storage facility for feces. As the rectal walls expand due to the materials filling it from within, stretch receptors from the nervous system located in the rectal walls stimulate the desire to defecate. If the urge is not acted upon, the material in the rectum is often returned to the colon where more water is absorbed. If defecation is delayed for a prolonged period, constipation and hardened feces results.
When the rectum becomes full the increase in intrarectal pressure forces the walls of the anal canal apart allowing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and peristaltic waves propel the feces out of the rectum. The internal and external sphincter allow the feces to be passed by muscles pulling the anus up over the exiting feces.
For the diagnosis of certain ailments, a rectal exam may be done.
Suppositories may be inserted into the rectum as a method of the administration for medicine.
The endoscopic procedures colonoscopy and sigmoidoscopy are performed to diagnose diseases such as cancer.
Body temperature can also be taken in the rectum. Rectal temperature can be taken by inserting a mercury thermometer for 3 to 5 minutes, or a digital thermometer until it "beeps", not more than 25 mm (1 inch) into the rectum via the anus. Due to recent concerns related to mercury poisoning, the use of mercury thermometers is now discouraged. Normal rectal temperature generally ranges from 36 to 38 °C (97.6 to 100.4 °F) and is about 0.5 °C (1 °F) above oral (mouth) temperature and about 1 °C (2 °F) above axillary (armpit) temperature.
Many pediatricians recommend that parents take infants and toddler's temperature in the rectum for two reasons:
- (1) Rectal temperature is the closest to core body temperature and in children that young, accuracy is critical.
- (2) Younger children are unable to cooperate when having their temperature taken by mouth (oral) which is recommended for children, ages 6 and above and for adults.
In recent years, the introduction of ear (tympanic) thermometers and changing attitudes on privacy and modesty have led some parents and doctors to discontinue taking rectal temperatures.
Due to the proximity of the anterior wall of the rectum to the vagina in females or to the prostate in males and the shared nerves thereof, rectal stimulation can result in sexual arousal. For further information on this aspect, see anal sex.
The anus is the opening at the lower end of the alimentary canal through which solid waste is eliminated from the body. It is found between two cheeks of the human buttocks adjacent to the male or female sex organs. The adjective anal refers to the anus, such as in 'anal area' or 'anal sex'.
"Anus" refers to the opening itself; inside of it, between the anus and the rectum, is the anal canal which is closed by a set of two sphincters.
The appearance of the anus resembles a tightly gathered rosebud in art. The skin around the anus is usually darker (more pigmented) than the rest of the buttocks. Some people lighten it by anal bleaching - a fashion trend that has originally come up in the porn industry.
The anus in spanking art
In spanking art, spanking photos and spanking videos, the spankee's anus is visible only if the following conditions are met:
- it is a bare bottom spanking,
- and the viewing angle is straight on (i.e not in side view or three-quarter view),
- and the legs are not fully closed, and
- the buttocks are not clenched together
Therefore, in most works of spanking art the spankee's anus is not in view. In drawings, three-quarter view is very common, in which the near buttock hides the spankee's anus irrespective of the legs.
The anus and human sexuality
The anus is an erogenous zone and stimulation of the anus can be experienced as erotic. It can provide an opening for the penis for sexual intercourse, but there are also other ways in which anal stimulation can be enjoyed:
- inserting a smooth (and usually, lubricated) object into the anus, such as a:
- inserting a decorative item, such as
- inserting a body part in the anus, such as
- in medical play:
- rectal temperature taking
- inspecting the inside of the anus using the finger or a speculum
- inserting fluid into the bowels via the anus (see enema)
- spanking the anus (called a bull's eye)
- Also see the page [ Medical play ]
These photos are presented for the purposes of identifying various body parts
|External||Head||Cheek • Mouth • Lip • Eye • Face • Hair • Nape • Neck • Nose|
|Torso||Abdomen • Anus • Back • Body • Breasts • Bubble butt • Butterfly buttocks • Buttocks • Cheek • Chest • Clitoris • Crotch • Dimples of Venus • Epidermis • Erogenous zone • Genitals • Gluteal cleft • Gluteal sulcus • Gluteus maximus • Hindquarter • Hip • Labia • Nipple • Penis • Perineum • Pubic hair • Pubis • Rectum • Rhombus of Michaelis • Sacral triangle • Scrotum • Skin • Small of the back • Sphincter • Spinal groove • Sweet spot • Testicles • Vagina • Vulva • Waist|
|Limb||Ankle • Arm • Calf • Finger • Foot • Hand • Knee • Lap • Leg • Palm • Thigh • Wrist|
|Internal||Blood • Coccyx • Kidneys • Muscle • Nociceptor • Pelvis • Rib cage • Sacrum • Spine|
|Effects||Erection • Handprint • Orgasm • Tear • Vaginal lubrication|