<prompt> Pyriform sinus is laterally bounded by what?Interarytenoid aeryThyroid aeryEpiglottisThyrohyoid membrane  <response>: On either side of the laryngeal orifice in humans is a recess, termed the piriform sinus also piriformrecess, pyriform sinus, piriform fossa, or smugglers fossa, which is bounded medially by the aryepiglottic fold, laterally by the thyroid cailage and thyrohyoid membrane. The fossae are involved in speech. 