The twelfth cranial nerves, also known as the hypoglossal nerves, are a pair of nerves that emerge from the base of the brainstem and primarily innervate the muscles responsible for controlling the movements of the tongue. They are the twelfth pair of cranial nerves and are denoted by the Roman numeral XII.
The twelfth cranial nerves are composed of motor fibers, meaning they carry signals from the brain to the target muscles. More specifically, they provide voluntary motor control to the intrinsic and extrinsic muscles of the tongue, which are involved in movements such as protrusion, retraction, and side-to-side motion. These nerves enable various functions related to speech, articulation, chewing, swallowing, and even the maintenance of proper tongue posture.
The twelfth cranial nerves originate from the hypoglossal nuclei located within the medulla oblongata of the brainstem. From there, they exit the skull through the hypoglossal canal and branch out to innervate the muscles of the tongue on both sides of the body.
Damage or dysfunction of the twelfth cranial nerves can result in a condition called hypoglossal nerve palsy. This can lead to difficulties in speaking, eating, and swallowing, as well as altered tongue movements and positions. Clinical assessment and diagnostic tests can help determine the extent of the nerve damage and guide appropriate treatment approaches, which may include speech therapy, targeted exercises, or surgical interventions.
