The dorsum of the tongue is convex and marked by a median sulcus, which divides it into symmetrical halves; this sulcus ends behind, about 2.5 cm from the root of the organ, in a depression, the foramen cecum (or foramen caecum), from which a shallow groove, the sulcus terminalis, runs lateral and anterior on either side to the margin of the tongue.
The foramen cecum is the point of attachment of the thyroglossal duct and is formed during the embryological descent of the thyroid gland.