A newborn has a persistent thyroglossal duct cyst that becomes infected and drains through the skin at the midline of the neck. The cyst moves upward with protrusion of the tongue. The thyroid gland begins its descent from which embryological structure?
- A First pharyngeal pouch endoderm
- B Second pharyngeal arch mesoderm
- C Foramen cecum at the junction of anterior 2/3 and posterior 1/3 of tongue ✓
- D Third pharyngeal arch endoderm
Correct answer: C. Foramen cecum at the junction of anterior 2/3 and posterior 1/3 of tongue
Explanation
The thyroid gland develops as an endodermal downgrowth from the foramen cecum — a pit on the dorsal surface of the tongue at the junction of the anterior two-thirds (derived from first arch) and posterior one-third (from third and fourth arches). The gland descends through the neck along the thyroglossal duct, which normally obliterates. Persistence forms a thyroglossal duct cyst; its connection to the tongue root explains why the cyst rises with tongue protrusion. First pharyngeal pouch forms the eustachian tube and middle ear.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.