Hypoglossal nerve
From Wikipedia, the free encyclopedia
| Nerve: Hypoglossal nerve | ||
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| Hypoglossal nerve, cervical plexus, and their branches. | ||
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| Plan of hypoglossal nerve. | ||
| Latin | N. Hypoglossus | |
| Gray's | subject #207 914 | |
| Innervates | genioglossus, hyoglossus, styloglossus, thyrohyoid, omohyoid, sternothyroid and sternohyoid | |
| To | ansa cervicalis | |
| MeSH | A08.800.800.120.330 | |
The hypoglossal nerve is the twelfth cranial nerve. 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, the nerve 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 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) and the accessory nerve (XI).
[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 at 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 motorneuron disease, such as fasciculation and atrophy.
[edit] Additional images
 Veins of the tongue. The hypoglossal nerve has been displaced downward in this preparation. |
