sentences:  The fossa is bounded, above, by the free crescentic edge of the vestibular ligament; below, by the straight margin of the vocal fold and laterally, by the mucous membrane covering the corresponding thyroarytenoid muscle.The anterior part of the ventricle leads up by a narrow opening into a pouch-like diverticulum, a mucous membranous sac of variable size called the appendix of the laryngeal ventricle.The appendix (also called the laryngeal saccule, pouch or Hilton's pouch) extends vertically from the laryngeal ventricle.