Hypoglossal nerve
243330
225758905
2008-07-15T07:30:51Z
Richardcavell
357679
/* External links */ This isn't a stub. Anyway, correct template name is lowercase.
{{Infobox Nerve |
Name = Hypoglossal nerve |
Latin = nervus hypoglossus |
GraySubject = 207 |
GrayPage = 914 |
Image = Gray794.png |
Caption = Hypoglossal nerve, [[cervical plexus]], and their branches. |
Image2 = |
Caption2 = |
Innervates = [[genioglossus]], [[hyoglossus]], [[styloglossus]] |
BranchFrom = |
BranchTo = [[ansa cervicalis]] |
MeshName = Hypoglossal+Nerve |
MeshNumber = A08.800.800.120.330 |
}}
The '''hypoglossal nerve''' is the twelfth [[cranial nerve]] (XII), leading to the tongue. The nerve arises from the [[hypoglossal nucleus]] and emerges from the [[medulla oblongata]] in the preolivary [[sulcus]] separating the ''olive'' and the ''pyramid''. It then passes through the [[hypoglossal canal]]. On emerging from the hypoglossal canal, it gives off a small meningeal branch and picks up a branch from the [[anterior]] [[ramus]] of [[Cervical spine|C1]]. It spirals behind the [[vagus nerve]] and passes between the [[internal carotid artery]] and [[internal jugular vein]] lying on the [[carotid sheath]]. After passing deep to the [[posterior]] belly of the [[digastric muscle]], it passes to the submandibular region to enter the [[tongue]].
It supplies motor fibres to all of the muscles of the [[tongue]], except the [[palatoglossus muscle]] which is innervated by the [[accessory 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 as [[fasciculation]] and [[atrophy]].
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 to the affected side.
==Additional images==
<gallery>
Image:Gray559.png|Veins of the tongue. The hypoglossal nerve has been displaced downward in this preparation.
Image:Gray694.png|Section of the medulla oblongata at about the middle of the olive.
Image:Gray699.png|Diagram showing the course of the arcuate fibers.
Image:Gray714.png|Transverse section passing through the sensory decussation.
Image:Gray719.png|Hind- and mid-brains; postero-lateral view.
Image:Gray792.png|Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.
Image:Gray795.png|Plan of hypoglossal nerve.
Image:Gray1013.png|The mouth cavity.
</gallery>
==External links==
* {{BrainInfo|hier|701}}
* {{LoyolaMedEd|GrossAnatomy/h_n/cn/cn1/cn12.htm}}
* {{NormanAnatomy|cranialnerves}} ({{NormanAnatomyFig|XII}})
{{Cranial nerves}}
[[Category:Peripheral nervous system]]
[[Category:Cranial nerves]]
[[ar:عصب تحت اللسان]]
[[de:Nervus hypoglossus]]
[[fr:Nerf hypoglosse]]
[[it:Nervo ipoglosso]]
[[lt:Poliežuvinis nervas]]
[[nl:Ondertongzenuw]]
[[ja:舌下神経]]
[[no:Nervus hypoglossus]]
[[pl:Nerw podjęzykowy]]
[[pt:Nervo hipoglosso]]
[[sr:Подјезични живац]]
[[fi:Kielen liikehermo]]
[[zh:舌下神经]]