
The thyroglossal duct is an epithelium-lined connection between the foramen cecum and the thyroid that forms during the descent of the thyroid during embryological development. It usually involutes in the 8th-10th week of gestation.
Variant anatomy
The thyroid may halt at any stage during its descent or leave rests of thyroid tissue along the course of the thyroglossal duct:

Related pathology
Failure of obliteration of the duct may lead to the formation of a thyroglossal duct cyst.