Besides the sphincter pupillae, the fibres of the ciliary muscle are stimulated.
The sphincter of Oddi surrounds the ampulla and prevents reflux of duodenal contents into the pancreatic duct.
Feeling confident you have the muscle tone required for a controlled venting operation, you allow the sphincter to slightly relax.
intestine must find its way ", outwards probably acting in this region the part of a sphincter.
be closed by a sphincter.