Hypoglossal nerve

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Nerve: Hypoglossal nerve
Image:Gray794.png
Hypoglossal nerve, cervical plexus, and their branches.
Latin	nervus hypoglossus
Gray's	subject #207 914
Innervates	genioglossus, hyoglossus, styloglossus
To	ansa cervicalis
MeSH	Hypoglossal+Nerve

The hypoglossal nerve is the twelfth cranial nerve (XII). 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 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 vagus nerve (X).

[edit] 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 (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/pareisis of the tongue, results in contralateral curvature of the tongue (toward the unimpaired side of the mouth).

[edit] Additional images

Gray559.png Veins of the tongue. The hypoglossal nerve has been displaced downward in this preparation.	Gray694.png Section of the medulla oblongata at about the middle of the olive.	Gray699.png Diagram showing the course of the arcuate fibers.	Gray714.png Transverse section passing through the sensory decussation.
Gray719.png Hind- and mid-brains; postero-lateral view.	Gray792.png Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.	Gray795.png Plan of hypoglossal nerve.	Gray1013.png The mouth cavity.

[edit] External links

• NeuroNames hier-701
• MedEd at Loyola GrossAnatomy/h_n/cn/cn1/cn12.htm
• Norman/Georgetown cranialnerves (XII)

v • d • e Nerves of head and neck: the cranial nerves
I-IV	olfactory • optic • oculomotor (superior branch, inferior branch) • trochlear
V: trigeminal	trigeminal ganglion • ophthalmic • maxillary • mandibular
VI: abducens	no significant branches
VII: facial	nervus intermedius • geniculate • inside facial canal (greater petrosal, nerve to the stapedius, chorda tympani) • at exit from stylomastoid foramen (posterior auricular, digastric • stylohyoid) • on face (temporal, zygomatic, buccal, mandibular, cervical)
VIII: vestibulocochlear	cochlear (striae medullares, lateral lemniscus) • vestibular (Scarpa's ganglion)
IX: glossopharyngeal	nucleus ambiguus • ganglia (superior, petrous) • tympanic (tympanic plexus, lesser petrosal) • carotid sinus • pharyngeal branches • pharyngeal plexus
X: vagus	ganglia (jugular, nodose) • in the jugular fossa (meningeal branch, auricular branch) • in the neck (pharyngeal branch, superior laryngeal ext and int, recurrent laryngeal, superior cervical cardiac) • in the thorax (inferior cardiac, pulmonary branches, anterior vagal trunk, posterior vagal trunk) • in the abdomen (celiac branches - renal branches - hepatic branches of anterior vagal trunk - anterior gastric branches of anterior vagal trunk - posterior gastric branches of posterior vagal trunk)
XI-XII	accessory • hypoglossal

de:Nervus hypoglossus

it:Nervo ipoglosso lt:Poliežuvinis nervas nl:Ondertongzenuw ja:舌下神経 no:Nervus hypoglossus pl:Nerw podjęzykowy pt:Nervo hipoglosso fi:Kielen liikehermo zh:舌下神经