What muscles does CN 12 innervate?
The hypoglossal nerve (CN XII) is exclusively a motor nerve carrying general somatic efferent fibers (GSE). It innervates all intrinsic and almost all extrinsic muscles of the tongue, as well as one suprahyoid muscle, the geniohyoid muscle.
What does cranial nerve XII do?
Cranial nerve 12 controls the: Genioglossus muscles, which push the tongue forward. Hyoglossus muscles that pull the tongue back and flatten it. Intrinsic muscles that change the tongue’s shape, including curving and narrowing.
What happens if the hypoglossal nerve is damaged?
The hypoglossal nerve can be damaged at the hypoglossal nucleus (nuclear), above the hypoglossal nucleus (supranuclear), or interrupted at the motor axons (infranuclear). Such damage causes paralysis, fasciculations (as noted by a scalloped appearance of the tongue), and eventual atrophy of the tongue muscles.
What causes hypoglossal nerve damage?
Hypoglossal nerves can be damaged unilaterally by a multitude of causes especially, tumors, infection, or trauma. The concept of trauma includes surgical trauma as with carotid endarterectomy (surgery to remove the plaques from the carotid artery). Rare bilateral lesions can be the result of radiation therapy.
How do you test for CN 12’s function?
The 12th CN is tested by having the patient stick out their tongue and move it side to side. Further strength testing can be done by having the patient push the tongue against a tongue blade. Inspect the tongue for atrophy and fasciculations.
Which spinal nerve serves the diaphragm?
The phrenic nerve originates at the C3 through C5 nerve roots, which exits the spinal canal at the neck root and descends caudally, parallel to the pericardial sac to provide the motor innervation to the diaphragm.
How do you test for hypoglossal nerve damage?
The hypoglossal nerve can be examined by asking a patient to protrude their tongue, move their tongue laterally, and place their tongue against their cheek to resist the opposing force of the examiner’s hand resting on the external cheek.
What causes 12th cranial nerve palsy?
Disorders of the 12th cranial nerve (hypoglossal nerve) cause weakness or wasting (atrophy) of the tongue on the affected side. This nerve moves the tongue. Hypoglossal nerve disorders may be caused by tumors, strokes, infections, injuries, or amyotrophic lateral sclerosis.
Can hypoglossal nerve damage be repaired?
Repair of Hypoglossal Nerve Injury Similar to facial nerve repairs, the ideal management involves establishment of a tension-free anastomosis (Avitia & Osborne, 2008). Although this is preferably performed with end-to-end anastomosis if possible, the use of interposition grafts can be used.
How do you access the 12th cranial nerve?
The 12th (hypoglossal) cranial nerve is evaluated by asking the patient to extend the tongue and inspecting it for atrophy, fasciculations, and weakness (deviation is toward the side of a lesion).
How do you fix cranial nerve damage?
The types of treatment options for cranial nerve disorders include:
- Medication.
- Microvascular Decompression (MVD)
- Gamma Knife® Perfexion™ Radiosurgery.
- Supra Orbital and Infra Orbital Peripheral Nerve Stimulation.
- Percutaneous Glycerol Rhizotomy.
- Research and Clinical Trials.
What causes a paralyzed diaphragm?
There are several known causes that can lead to diaphragm paralysis: Birth defects such as congenital central hypoventilation syndrome. Diseases of the nervous system, such as amyotrophic lateral sclerosis (ALS) or multiple sclerosis. Injury, such as an upper cervical spinal cord injury that has spared the phrenic …
How is hypoglossal nerve treated?
Once a diagnosis is made, treatment can begin. A lot of research is focusing on direct nerve repair as well as nerve transfers to correct problems such as facial paralysis, and surgical techniques are improving regarding the hypoglossal nerves as well as several other nerves of the face.
How do you test for cranial nerve XII?
How long does it take for hypoglossal nerve to heal?
Although there has been a report of permanent nerve damage, patients with transient hypoglossal palsies are known to fully recover within 6 months of incidence. Postoperative hypoglossal nerve palsy may cause great discomfort as it is related to speech, a critical aspect in daily life.