Which cranial nerve nucleus is cited as an example of an axial motor nucleus in the brainstem?

• A. CN XII (Tongue)
• B. CN III (Oculomotor)
• C. CN VII (Facial)
• D. CN X (Vagus)

Answer: (A)

Axial motor control in the brainstem refers to nuclei that innervate muscles located along the body's central axis, especially in the head and neck. The tongue fits this category as an axial muscle of the head and neck, with its intrinsic and most extrinsic muscles innervated by the hypoglossal nucleus in the medulla. The hypoglossal nucleus sends fibers via the hypoglossal nerve to move the tongue, which is essential for speech and swallowing. Other listed nuclei govern eye movements, facial expression, or pharyngeal/laryngeal muscles and belong to different motor groups, not the axial category. Therefore, the hypoglossal nucleus is the example of an axial motor nucleus in the brainstem.