The thyroid gland descends from the foramen caecum of the tongue to its final position in the neck, guided by the thyroglossal duct. Thyroglossal duct cysts characteristically move upward on swallowing and on protrusion of the tongue because:

• A They are attached to the hyoid bone and the lower end of the thyroglossal duct
• B They arise from the thyroid isthmus and move with it
• C They are located within the sternohyoid muscle which contracts on swallowing
• D The fibrous cord remnant of the thyroglossal duct is tethered to the body of the hyoid and the foramen caecum ✓

Explanation

The thyroglossal duct descends from the foramen caecum at the tongue base (junction of anterior 2/3 and posterior 1/3), passes through or just below the body of the hyoid, and extends to the isthmus of the thyroid. Any cyst or remnant along this tract is connected by a fibrous cord to the foramen caecum above and passes near or through the hyoid. Tongue protrusion (which elevates the foramen caecum via hyoglossus/tongue base movement) and swallowing (hyoid elevation) draw the fibrous remnant upward, thus elevating the cyst. The Sistrunk operation removes the cyst together with the central portion of the hyoid body and the tract up to the foramen caecum to prevent recurrence.

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

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Written and medically reviewed by the StethoPrep medical team.