Final answer:
The sulcus terminalis is the boundary that separates the anterior from the posterior tongue, with each part having different functions and innervation.
Step-by-step explanation:
The boundary that separates the anterior from the posterior tongue is known as the sulcus terminalis. This V-shaped groove divides the tongue into the anterior two-thirds and the posterior one-third. Functions, such as taste, are separated between these regions, with the anterior tongue primarily responsible for the perception of sweet, salty, sour, and umami tastes, while the posterior tongue is sensitive to bitter tastes. The anterior part contains fungiform papillae, which are mushroom-shaped structures containing taste buds. In contrast, the posterior part houses the lingual tonsils and is composed of lymphoid tissue that contributes to the immune defense of the body. Sensory and motor function in the tongue is complex with different cranial nerves innervating each part; the anterior two-thirds of the tongue receive taste sensation through the chorda tympani branch of the facial nerve (Cranial Nerve VII), while the posterior third is innervated by the glossopharyngeal nerve (Cranial Nerve IX) for both taste and general sensation.