The thyroid gland develops from which embryological structure, and a thyroglossal duct cyst is found in the midline at what level in the majority of cases?

• A First pharyngeal pouch endoderm; cysts found at the angle of mandible
• B Third pharyngeal pouch; cysts found at the lower neck near the thyroid
• C Neural crest cells from the floor of the fourth pharyngeal arch; cysts found at suprasternal notch
• D Foramen cecum at junction of anterior two-thirds and posterior one-third of tongue; cysts most commonly found at or just below the hyoid bone (juxtahyoid level) ✓

Explanation

The thyroid gland originates from the endoderm at the foramen cecum, located at the apex of the sulcus terminalis between the anterior two-thirds and posterior one-third of the tongue. It descends via the thyroglossal duct, which normally obliterates. Thyroglossal duct cysts occur anywhere along this descent path from the tongue base to the thyroid, but 60–65% are found at or just inferior to the hyoid bone (juxtahyoid level). The Sistrunk operation (excision of the cyst + central hyoid body segment + tract to foramen cecum) is the treatment of choice to prevent recurrence, because the duct has an intimate relationship with the hyoid.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.