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Terminal sulcus of tongue or sulcus terminalis linguae in Latin is a V-shaped shallow groove that separates the convex dorsum of the tongue into a superior oral surface, and a posterior pharyngeal surface. It is part of the inferior margin of the oropharyngeal isthmus (isthmus of the fauces) that lies in between the oral and pharyngeal cavities as well.
At the apex of the sulcus terminalis, is a small median depression called the foramen cecum. From it, the two limbs of the sulcus run anterolaterally on either side towards the tongue’s margin where the palatoglossal arches are. The foramen cecum marks the site of the upper end of the embryonic thyroid diverticulum (thyroid duct), and the epithelial invagination that gives rise to the thyroid gland.
The oral and pharyngeal parts of the tongue (or anterior two-thirds and posterior one-third of the tongue) differ in their mucosa, innervation, lymphatic drainage, and developmental origin too. The glossopharyngeal nerve carries taste and general sensation from the pharyngeal surface. As for the oral surface, the lingual nerve, a branch from the mandibular branch (V3) of the trigeminal nerve is responsible for the somatosensory perception. Taste perception however, is carried into the central nervous system by a branch from the facial nerve, the chorda tympani.
The tongue, including the terminal sulcus, is supplied by the lingual artery that arises from the external carotid artery in the neck. As for drainage, both dorsal lingual and deep lingual veins are responsible.
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