Lower esophageal sphincter

This is also called the cardiac sphincter (or gastroesophageal sphincter) and it marks the junction between the esophagus and the stomach. It maintains a constant tone of about 30 mmHg which is higher than the relaxed tone in the midesophagus and only relaxes in front of a peristaltic wave initiated by swallowing which helps to propel swallowed material past this physiological sphincter. This tone may increase prior to sneezing.

The sphincter does not have anatomical features similar to other sphincters in the gastrointestinal tract but the following helps to make it a functional sphincter.

  • The mucosal fold at the esophagogastric junction has valvular function

  • The acute angle at this junction is sphincteric in action

  • Circular muscle in the lower esophagus seems to act like a sphincter and arrangement of smooth muscle around the esophagogastric junction is also effective in sphincteric action.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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