The Pharyngeal Apparatus Practice Test

The structures tympanic cavity and auditory tube come from the first pharyngeal pouch. During development, the first pouch forms a tubotympanic recess that expands to become the tympanic cavity of the middle ear and, extending toward the nasopharynx, the pharyngotympanic (auditory) tube. The other pouches contribute to different structures—second pouch to palatine tonsil components, third pouch to thymus and inferior parathyroids, and fourth pouch to superior parathyroids and related cells—so they do not form the tympanic cavity or the auditory tube.