1. Accessory and Hypoglossal nerves

2. 11th CN: Accessory Nerve Type: Motor (SVE) Origin : 2 roots
cranial root: arises from the medulla
Spinal root : from upper 5 cervical segments
Emerges from : jugular foramen then the 2 roots separate

3. Cranial Part Origin: Nucleus ambiguus (NA) in the medulla oblongata
Site of emergence: The fibers emerge from the anterior surface of the medulla oblongata between the olive and the inferior cerebellar peduncle (ICP)

4. Spinal Part
Origin:
Formed by the axons of the nerve cells in the spinal nucleus which is located in the ventral grey horn in the upper 5 cervical segments

5. The nucleus ambiguus and the spinal nucleus receive bilateral corticonuclear fibers (from both cerebral hemispheres)

6. Course The cranial root :
joins the vagus nerve and distributed with its pharyngeal and laryngeal branches
Spinal part:
fibers emerge from the spinal cord, form a nerve trunk that ascends into the cranial cavity through the foramen magnum, pass laterally and join the cranial root.

7. Course Function: Spinal part ctd.:
Descends first in the carotid sheath (bet. I.C.A. and I.J.V. )
Then emerges from the sheath, pass backwards, to pierce the sternomastoid m., cross the posterior triangle of the neck to end in the trapezius
Supply both muscles
Function:
Movements of the soft palate, larynx, pharynx.
Controls the movements of neck

9. Lesion Lesion results into: Difficulty in swallowing and speech
Inability to turn the head
Inability to shrug (raise) the shoulder
Winging of scapula

10. 12th CN: Hypoglossal Nerve
Type: Motor (GSE)
Origin: Hypoglossal nucleus of the medulla (in the floor of 4th ventricle)
Foramen of exit from skull: Hypoglossal canal

11. The hypoglossal nucleus receives corticonuclear fibers from both cerebral hemispheres EXCEPT
the region that supplies genioglossus muscle (it receives contralateral supply only)
Also receives afferent fibers from nucleus solitarius and trigeminal sensory nucleus.

12. Site of emergence:
The fibers emerge from the anterior surface of the medulla oblongata between the pyramid and the olive.
Pyramid
Olive

13. Course
Descends in the carotid sheath between internal jugular vein and internal carotid artery
It leaves the sheath and pass forward and medially crossing ICA &ECA
It enters the digastric triangle
Finally , it pass deep to the mylohyoid muscle to reach the tongue where it breaks into terminal branches

14. Course
During its initial course, it carries C1 fibers which leave in a branch to take part in the formation of ansa cervicalis (a loop of nerves supplying neck muscles)
C1 fibers

15. Distribution: Function:
Supplies motor innervation to all of the muscles of the tongue Except the palatoglossus (which is supplied by the vagus).
Carries proprioceptive afferents from the tongue muscles.
Function:
Controls the movements and shape of the tongue during speech and swallowing

16. LESION Lesion of the nerve results into: Loss of tongue movements
Difficulty in chewing and speech
The tongue paralyses, atrophies, becomes shrunken and furrowed on the affected side (LMN paralysis)
On protrusion, tongue deviates to the affected side
If both nerves are damaged, person can’t protrude tongue
Normal