Sphincter - wikipedia Sphincter Sphincter Identifiers Anatomical terms of muscle ( edit on Wikidata ) Look up sphincter in Wiktionary, the free dictionary. A sphincter is a circular muscle that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. Sphincters are found in many animals. There are over 60 types in the human body, some microscopically small, in particular the millions of precapillary sphincters. Sphincters relax at death, often releasing fluids. Contents 1 Functions 2 Classifications 3 Examples 4 References Functions Sphincters control the passage of liquids and solids. This is evident, for example, in the blowholes of numerous marine mammals. Many sphincters are used every day in the normal course of digestion. For example, the lower esophageal sphincter ( or cardiac sphincter ), which resides at the top of the stomach, keeps stomach acids and other stomach contents from pushing up and into the esophagus. During contraction of sphincter / circular muscles, the lumen ( opening ) associated with the sphincter constricts ( closes ). This constriction is caused by the shortening of the sphincter muscle. Relaxation of a sphincter muscle causes it to lengthen, opening the lumen. Classifications Sphincters can be further classified into functional and anatomical sphincters : Anatomical sphincters have a localised and often circular muscle thickening to facilitate their action as a sphincter. Functional sphincters do not have this localised muscle thickening and achieve their sphincteric action through muscle contraction around ( extrinsic ) or within ( intrinsic ) the structure. Sphincters can also be voluntarily or involuntarily controlled : Voluntary sphincters are supplied by somatic nerves. Involuntary sphincters are stimulated by autonomic nerves. Examples Diagram of Ileocaecal valve and sphincter The sphincter pupillae, or pupillary sphincter, belonging to the iris in the eye. The orbicularis oculi muscle, a muscle around the eye. The upper and lower oesophageal sphincters. The lower sphincter, or cardiac sphincter, at the upper portion ( cardia ) of the stomach. This sphincter prevents the acidic contents of the stomach from moving upward into the esophagus. The pyloric sphincter, at the lower end of the stomach. The ileocecal sphincter at the junction of the small intestine ( ileum ) and the large intestine, which functions to limit the reflux of colonic contents back into the ileum. The sphincter of Oddi, or Glisson 's sphincter, controlling secretions from the liver, pancreas and gall bladder into the duodenum. The sphincter urethrae, or urethral sphincter, controlling the exit of urine from the body. At the anus, there are two sphincters which control the exit of feces from the body ( see internal anal sphincter and external anal sphincter ). The inner sphincter is involuntary and the outer is voluntary. The microscopic precapillary sphincters function to control the blood flow into each capillary in response to local metabolic activity. The preputial sphincter, belonging to the human foreskin. References ^ Jump up to : Vander, Arthur ; Sherman, James ; Luciano, Dorothy ( 1994 ). Human Physiology : The Mechanism of Body Function ( Sixth Edition, International Edition ). McGraw Hill, Inc. pp. 437 -- 440. ISBN 0 - 07 - 113761 - 0. Jump up ^ `` Medscape Log In ''. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Sphincter&oldid=843993325 '' Categories : Muscular system Hidden categories : Pages with unresolved properties Articles which use infobox templates with no data rows Talk Contents About Wikipedia Afrikaans Aragonés Bân - lâm - gú Беларуская Български Català Dansk Deutsch Eesti Español Esperanto Euskara Français Frysk Galego 한국어 Ido Italiano Kurdî Nederlands 日本 語 Polski Português Русский Suomi தமிழ் Türkçe Українська 中文 21 more Edit links This page was last edited on 1 June 2018, at 21 : 06 ( UTC ). Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: how many sphincter muscles are in the body
Answer: 60 types in the human body