Science Fair Project Encyclopedia
Sphincter
From late Latin sphincter, from Greek sphinkter, band, contractile muscle, from sphingein, to bind tight.
A sphincter is a ring-like muscle that normally maintains constriction of a natural body passage or orifice and that relaxes as required by normal physiological functioning.
Some examples of sphincters include:
- Anus
- Cardia, at the upper portion of the stomach
- Sphincter urethrae, or Urethral sphincter
- Pyloric sphincter, at the lower end of the stomach
- Sphincter pupillae, or Pupillary sphincter, belonging to the iris in the eye
10-26-2009 08:16:03
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details