- Hypoglossal nerve
Infobox Nerve
Name = Hypoglossal nerve
Latin = nervus hypoglossus
GraySubject = 207
GrayPage = 914
Caption = Hypoglossal nerve,cervical plexus , and their branches.
Caption2 =
Innervates =genioglossus ,hyoglossus ,styloglossus
BranchFrom =
BranchTo =ansa cervicalis
MeshName = Hypoglossal+Nerve
MeshNumber = A08.800.800.120.330
The hypoglossal nerve is the twelfthcranial nerve (XII), leading to the tongue. The nerve arises from thehypoglossal nucleus and emerges from themedulla oblongata in the preolivarysulcus separating the "olive" and the "pyramid". It then passes through thehypoglossal canal . On emerging from the hypoglossal canal, it gives off a small meningeal branch and picks up a branch from theanterior ramus of C1. It spirals behind thevagus nerve and passes between theinternal carotid artery andinternal jugular vein lying on thecarotid sheath . After passing deep to theposterior belly of thedigastric muscle , it passes to the submandibular region to enter thetongue .It supplies motor fibres to all of the muscles of the
tongue , except thepalatoglossus muscle which is innervated by theaccessory nerve , which runs in part with the vagus nerve (Cranial nerve X).Testing the hypoglossal nerve
To test the function of the nerve, a person is asked to poke out their
tongue . If there is a loss of function on one side ( [http://www.answers.com/topic/unilateral-paralysis unilateral paralysis] ) the tongue will point towards the affected side.The strength of the tongue can be tested by getting the person to poke the inside of their cheek, and feeling how strongly they can push a finger pushed against their cheek - a more elegant way of testing than directly touching the tongue.
The tongue can also be looked at for signs of
lower motor neuron disease, such asfasciculation andatrophy .Ipsilateral paralysis/paresis of the tongue results in contralateral curvature of the tongue (apex toward the unimpaired side of the mouth) i.e., the tongue will point away from the affected side.
=AdditionalExternal links
*
*
* (NormanAnatomyFig|XII)
Wikimedia Foundation. 2010.