Foramen Caecum Significance — MFDS Part 1 MCQ

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ModerateAnatomy (Head & Neck)Foramen Caecum SignificanceMFDS Part 1

The foramen caecum is a midline landmark at the apex of the sulcus terminalis. It marks the site of origin of which embryological primordium?

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Correct answer: B — Median thyroid primordium

The foramen caecum marks the site at which the median thyroid primordium develops in the floor of the primitive pharynx. The primordium subsequently descends through the neck along the thyroglossal pathway to reach its definitive pretracheal position. The thyroglossal duct normally disappears; persistent remnants may produce a thyroglossal duct cyst or contribute to ectopic thyroid tissue. The parotid, submandibular and sublingual glands develop as separate epithelial buds within the primitive oral cavity and are not derived from the foramen caecum. The lingual tonsil develops from lymphoid tissue in the posterior third of the tongue rather than from the thyroid primordium.

Reference: Zander DA, Smoker WRK. Imaging of ectopic thyroid tissue and thyroglossal duct cysts. Embryological development section. Radiographics. 2014;34(1):37-50. https://pubmed.ncbi.nlm.nih.gov/24428281/