Eustachian Tube Origin — MFDS Part 1 MCQ

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ModerateAnatomy (Head & Neck)Eustachian Tube OriginMFDS Part 1

The first pharyngeal pouch forms the tubotympanic recess. Its distal expansion contributes to the tympanic cavity, while its proximal narrow portion persists as which adult structure?

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Correct answer: B — Pharyngotympanic (Eustachian) tube

The correct answer is B, the pharyngotympanic or Eustachian tube. The endodermal first pharyngeal pouch expands as the tubotympanic recess: its distal part contributes to the epithelial lining of the tympanic cavity, whereas its proximal narrow part forms the pharyngotympanic tube connecting the middle ear to the nasopharynx. The external acoustic meatus develops from first pharyngeal cleft ectoderm, not the pouch. The thyroglossal duct is associated with thyroid descent. A branchial fistula is an abnormal persistence of pharyngeal apparatus structures rather than a normal derivative. The nasolacrimal duct develops from ectoderm in the naso-optic groove.

Reference: Park K, Lim DJ. Luminal development of the eustachian tube and middle ear: murine model. Yonsei Medical Journal. 1992;33(2):159–167. https://pubmed.ncbi.nlm.nih.gov/1413893/