Anus

It is known like anus to the terminal end of . It is constituted by voluntary sphincter (external sphincter of the anus), covered of , being an opening through which the materials of remainder of digestion (fecales lees) they leave the body.

Theoretically the anus is a simple orifice in that the alimentary canal finishes on the other hand inferior, in the same way in which oral cavity it begins in its superior part. To the anal orifice it is added to him above by the most inferior part of rectum that it precedes, and by down, the zone that the continuous thing and that surrounds it. Thus the anus, becomes a conduit of about 15 to 20 millimeters in length (anal channel) through as run lees during defecación.

Situation and relations of the anus

The anus is located in the mean line of the body, a little behind the biisquiática line. It is opened in the later vertex of periné, a little in front of cóccix and at heart of the longitudinal furrow that separates the two rumps. The anus is previous and a little more superficial in the woman who in the man.

The anus is related by the sides to the muscle external sphincter, the isquiorrectales graves and to the elevators of the anus, behind to rafe anococcígeo and the muscular fascículos that in him are intertan and ahead with in the man and with in the woman.

Limits of the anus

The limits of the anus are vague due to the divergence of the different anatomists.

• By above, the limit is a circular line, anorrectal line, dentated line or pectínea line, irregularly winding, that happens through the edge of the semilunar valves of the rectum. In this line the rectum of the skin separates, endoderm of .
• Underneath, in periné, the anus is limited by anoperineal line, difficult to delimit, from which, the hair arises from periné. The zone of periné that surrounds to the anoperineal line calls anal margin.

anal channel it is the conduit that extends from the line indented to the anoperineal line.

Conformation of the anus

The anus by outside has circular form when it is expanded, when they pass lees or an object is introduced. In rest it has form of anteroposterior crack of that they leave from broadcast form certain number of you fold, fold radiated of the anus that they are pronounced with the contraction of the anus and that they erase completely when the orifice dilates. The skin that surrounds to the anal orifice calls margin of the anus and it is type of a thinner, redder, constantly humid skin and without hair. Loosely pelos A aparecen partir de la línea anoperineal y suelen estar más desarrollados EN el hombre que EN la more mujer.

Anatomical constitution of anus

The anal conduit is formed by a muscular apparatus and modified skin.

• Muscular apparatus: It is formed by circular smooth fibers ready by outside the mucosa and that form internal sphincter of the anus, by circular fluted muscular fibers that form external sphincter of the anus. Other muscles related to the anus are: the retractive muscle of the anus, the rectouretral muscle and the elevating muscle of the anus.
• Cutaneous coating: The anus is covered by modified skin, thinner, less rich in papilas and that lacks completely hairs and glands. that it covers the anal channel is epitelio escamoso nonqueratinizado. Over the superior limit of the anal channel (pectínea line), one exists zone of transition in the rectum of about 6 to 12 mílímetros, in which epitelio escamoso passes to be epitelio cylindrical to columnar of a progressive form.

Glasses and nerves of the anus

The circulation and inervacón of the anus are confused with the one of the rectum and those of periné. of the anus comes in their majority of the inferior hemorroidal artery, branch of the artery pudenda commits. The lymphatic glasses end as much at the hypogastric ganglia, like in the exteros iliacos like in lymphatic ganglia inguinales.

Sexual use

He is frequent in sexual relations to use the anus like organ of to please (anal sex), often by morbo to have new sensations, in other occasions because he is not recommendable to make the act by its habitual conduit, or because does not have much hunger by diverse reasons (among them fear to , or ), but coverall where it is practiced more is in the relations homosexuals.