Cranial nerve XIIs, also known as the hypoglossal nerves, are a pair of motor nerves that originate from the brainstem and control the movements of the tongue. They are one of the 12 pairs of cranial nerves that emerge directly from the brain rather than the spinal cord.
The cranial nerve XII emerges from the medulla oblongata, which is the lowermost part of the brainstem. It exits the skull through the hypoglossal canal and then branches out to supply motor fibers to the intrinsic and extrinsic muscles of the tongue. These muscles are responsible for crucial functions such as swallowing, speech, and the movement of food around the mouth.
The hypoglossal nerves are unique among the cranial nerves as they only carry motor information and do not have any sensory components. This means that they only transmit commands from the brain to the muscles of the tongue, without receiving any signals from the tongue or other parts of the body.
Injury or damage to the cranial nerve XIIs can result in various symptoms including difficulty in speaking, swallowing problems, or weakness and atrophy of the tongue. Neurological disorders such as strokes, trauma, or certain diseases can cause dysfunction of these nerves.
Overall, the cranial nerve XIIs play a crucial role in facilitating the movements and functions of the tongue, which are vital for speaking, swallowing, and proper oral hygiene.
