cns anatomy

1. Hypoglossal Nerve
(Cranial Nerve XII)
Dr. Mohamed Alzain Mohamed

2. (‫يلقي‬ ‫ال‬ ‫بالكلمة‬ ‫ليلقي‬ ‫الرجل‬‫إن‬‫لها‬
‫خريف‬‫سبعين‬ ‫به‬ ‫فتهوي‬ً‫ال‬‫با‬‫في‬ً‫ا‬
‫جهنم‬)

3. .
hypoglossal nerve is a motor nerve
that supplies all the intrinsic
muscles of the tongue as well as
the styloglossus, the hyoglossus,
and the genioglossus muscles.

4. Muscles of Tongue

5. .

6. Components
 GSA

7. Hypoglossal Nucleus
 beneath the floor of the lower part of the fourth
ventricle .
 receives corticonuclear fibers from both cerebral
hemispheres.
 cells responsible for supplying the genioglossus
muscle only receive corticonuclear fibers from
the opposite cerebral hemisphere.

9. Course of the Hypoglossal Nerve
 emerge on the anterior surface of the medulla
oblongata between the pyramid and the olive .
 leaves the skull through the hypoglossal canal.
 between the internal carotid artery and the
internal jugular vein .
 passes deep to the posterior margin of the
mylohyoid muscle lying on the lateral surface of
the hyoglossus muscle.

10. Hypoglossal nerve lesions
 Damage to the hypoglossal nerve in the neck
would result in an ipsilateral lower motor neuron
lesion.
 This would cause the protruded tongue to
deviate to the side of the lesion. Why ?

11. Lingual nerve is at risk during removal of the lower third molar or during operations of the
submandibular gland / duct
Damage to the hypoglossal nerve – tongue
deviates to the paralyzed side; longstanding
paralysis wasting of the muscles
Normal
Paralysis
Normal genioglossus pulls the same side forwards leaving the paralyzed side
stationary

12. why?
 If a patient has a lesion of the corticonuclear
fibers  upper motor neuron.
 on protrusion, the tongue will deviate to the side
opposite the lesion. Why ?

13. ‫اكبركذبة‬

14. ‫إهداء‬