LINGUAL THYROID GLAND

The thyroid gland arises from a ventral invagination of the pharyngeal entoderm just anterior to the first branchial cleft. This point of invagination marks in later life the site of the foramen cecum linguae. The anlage is first a hollow tube. The caudal portion of this tube soon becomes solid and grows down or is dragged down with the trachea. As it descends into the neck it becomes bilobed, and the thyroglossal duct has a double lumen in the caudal portion. 1 The thyroglossal tract begins to atrophy by the fifth week of fetal life, and the bilobed pouch becomes differentiated into the isthmus and lateral lobes of the thyroid gland. The descent of the thyroid anlage may be arrested at any point between the foramen cecum and the normally placed thyroid gland. The resulting location of these glandular masses can be designated as lingual, sublingual, suprahyoid, infrahyoid, pretracheal or