Which structure is primarily associated with the hypoglossal nucleus?

Which structure is primarily associated with the hypoglossal nucleus?

• A. Tongue
• B. Eye
• C. Larynx
• D. Heart

Answer: (A)

Cranial nerve motor nuclei are organized so each nucleus mainly controls a particular structure, and the hypoglossal nucleus is the somatic motor center for the tongue. Its neurons send axons that form the hypoglossal nerve, which innervates all intrinsic tongue muscles and most extrinsic tongue muscles. That link to tongue movements for speech and swallowing is why the tongue is the primary structure associated with this nucleus. If this nucleus or its nerve is injured on one side, you’d see weakness of tongue muscles on that side, and when the patient sticks out the tongue, it deviates toward the side of the lesion because the intact side pushes it in that direction. Other choices don’t fit because eye movements are controlled by the oculomotor, trochlear, and abducens nuclei; the larynx is mainly innervated by branches of the vagus nerve; and the heart is regulated by autonomic centers outside this nucleus.

Cranial nerve motor nuclei are organized so each nucleus mainly controls a particular structure, and the hypoglossal nucleus is the somatic motor center for the tongue. Its neurons send axons that form the hypoglossal nerve, which innervates all intrinsic tongue muscles and most extrinsic tongue muscles. That link to tongue movements for speech and swallowing is why the tongue is the primary structure associated with this nucleus.

If this nucleus or its nerve is injured on one side, you’d see weakness of tongue muscles on that side, and when the patient sticks out the tongue, it deviates toward the side of the lesion because the intact side pushes it in that direction.

Other choices don’t fit because eye movements are controlled by the oculomotor, trochlear, and abducens nuclei; the larynx is mainly innervated by branches of the vagus nerve; and the heart is regulated by autonomic centers outside this nucleus.