4 terms

Sphincters of the larynx

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Sphincter
A ringlike muscle which closes an orifice or passage
Aryepiglottic Sphincter
• Muscle fibers embedded in aryepiglottic fold surrounding pear shaped opening (aditus) into laryngeal cavity.
• First line of defense against foreign objects.
• Closes during swallowing and vomiting--preventing entry of food, liquid or vomitus into respiratory tract.
• Opening is called upper sphincter of larynx.
Upper
Ventricular Sphincter
• Lies between laryngeal vestibule and ventricle.
• During normal phonation, ventricular folds remain in quiet, open position.
• When the ventricular muscles contract, they meet at midline, sealing or closing the sphincter.
• True vocal folds will always adduct first, however.
• Increases subglottic pressure by adding another "door" to keep air in lungs and foreign objects out.
Middle
True Vocal Fold Sphincter
• Third door of closure.
• Not effective in preventing outflow of air during effort closure.
• Third line of defense in keeping foreign objects our of lungs.
• May close independently of other two sphincters.
• All three sphincters close during swallowing.
• Opens and closes rapidly as we are phonating
lower