<prompt> Pyriform sinus is laterally bounded by what ?Interarytenoid aeryThyroid aeryEpiglottisThyrohyoid membrane  <response>: Ans. is d i.e., Thyrohyoid membrane It lies on either side of the larynx and extends from pharyngoepiglottic fold to the upper end of esophagus. ? It is bounded by :- i Superiorly - Pharyngoepiglottic folds ii Inferiorly - Lower border of cricoid iii Laterally - Thyrohyoid membrane and thyroid cailage iv Medially - Aryepiglottic fold Posterolateral surface of arytenoids and cricoid cailages 