It is relatively simple for round shaped sphincters to either dilate or contract.
A rat's sphincter is a muscular ring that helps control the entry and exit of substances from its digestive system. It regulates the passage of food and waste materials through the digestive tract.
outer anal sphincter
ileocecal sphincter (valve)
cardiac sphincter; or gastroesophageal sphincter; or lower esophageal sphincter (LES); or esophageal sphincter from http://en.wikipedia.org/wiki/Cardia
The pyloric sphincter regulates passage of chymefrom the stomach
Sphincter of Oddi.
cardiac sphincter/lower esophageal sphincter (LES)
Sounds like a deer mouse.
What is the function of the cardiac sphincter?
Not that sphincter but yes they do have one of their own.
esophagal sphinter is a sphincter is actullal found there end of esophagous,
the sphincter that separates the stomach from the small intestine is the pyloric sphincter