2217 Cranial Nerves Slides

Human Neurobiology 910.217

Brainstem and Cranial Nerves II

Prof. Stuart Bunt


Patterning of the cranial nerves

Human Neurobiology 910.217A reminder about embryology


Names and NumbersUnderstand the names!

Olfactory I

Optic II

Oculomotor III

Trochlear IV

Trigeminal V

Abducens (t) VI

Facial VII

Vestibulocochlear VIII

Glossopharyngeal IX

Vagus X

Accessory XI

Hypoglossal XII

Sensory Sensory & motor Motor


Nerves covered in other lectures

1 Olfactory 2 Optic 3,4,6 Extraocular eye muscles 8 Vestibulo-cochlear

5 Motor and Sensory to the face and muscles of mastication (sensory, motor and mesencephalic nucleus for proprioception)


Note position of nerves on the brainstem

I Cerebrum

II Diencephalon

III, IV Midbrain

V Pons

VI, VII, VIII Junction : Pons-Medulla

IX, X, XI, XII Medulla oblongata


Nerves run from 1 to 12


Cranial nerves exit from the skull

except spinal branch of accessory (XI), which has some spinal roots


Can use anatomical knowledgeto identify sites of lesions

Remember positions 1-12 Note many pathways

(which you will learn later) pass nearby

Cranial nerve symptoms usually pretty obvious

Often serious (brainstem involvement)


Sensory cranial nerves 1. Olfactory, only sensation

to enter the cortex without passing through the thalamus (old sense?)

Rhinencephalon forms the cortex?


Sensory nerves

2. Optic (chiasm) 8. Vestibulo-cochlear


Motor nerves

3. Occulomotor extraolcular eye

muscles except:-

4. Trochlear (only one that emerges dorsally) trochlear muscle

6. Abducens lateral rectus


Motor nerves (cont.) 11. Accessory 12. Hypoglossal

5. Trigeminal 7. Facial 9. Glossopharyngeal 10. Vagus

Mixed nerves


Facial Nerve (a) The nerve of the second

arch Contributes to ear formation Tongue formation Facial musculature migrates

up over first arch

A mixed (sensory and motor) cranial nerve

Sensory from the ear Special sensory from the

tongue


Facial Nerve (b)

Motor to the muscles of facial expression, stylohyoid, posterior belly of digastric and stapedius (to dampen loud sounds), all attached to structures derived from the second pharyngeal arch.


Facial Nerve (c)

Viscero-motor (parasympathetic) to pterygopalantine ganglion

the glands of the mucosa of the nose and palate the lacrimal gland

submandibular ganglion submandibular and sublingual salivary glands

otic ganglion parotid gland


Innervation of the tongue


Clinical Evaluation Upper Motor

Neuron cortex controls lower

opposite face forehead and eye

closure dual consensual reflexes

Lower Motor Neuron all muscles on oneside affected taste affected


7th nerve damage

Bells palsy pain around ear no sensory impairment complete palsy rapid recovery(2-8wks) Entrapment in facial

canal after infection? steroids in severe cases

where taste affected


Other 7th nerve lesions

Ramsay-Hunt syndrome Herpes Zoster of 7th

nerve very severe pain in ear vescicles poor recovery

Hemifacial spasm irritation of nerve by

blood vessel?


Glossopharyngeal Nerve (9) Nerve of the third pharyngeal arch somatic motor to stylopharyngeus visceral motor to parotid via otic

ganglion special sense to the posterior 1/3 of the

tongue sensory to posterior pharynx, soft

palate, post. 1/3 of the tongue, tympanum, etc.

Sensory from Carotid sinus (pressure) and carotid body (pCO2)

Important for swallowing reflex.


Vagal Nerve (10) The wanderer cf vagrantnerve of 4th Arch Motor to all smooth muscle Secretory to all glands Afferent from all mucous surfaces in the gut

and its derivatives as far as the splenic flexure Motor to all muscles of the larynx, pharynx

and palate (except stylopharyngeus and tensor veli palatini)

Taste from a few taste buds on the epiglottis Inhibits cardiac muscle Sensory to the outer ear drum, external

auditory meatus and behind the auricle


Accessory Nerve (11) Motor nerve to the

sternocleidomastoid muscle and trapezius

A somitic, spinal nerve that re-enters the foramen magnum to look like a cranial nerve. (accessoryto the vagus)

Has both spinal and brainstem origins

Damage leads to trouble turning the head

Human Neurobiology 910.217Hypoglossal Nerve

Motor nerve supplies occipital somite derivatives

Intrinsic and extrinsic muscles of the tongue

Leaves the brainstem above the olive as a series of small rootlets

Damage leads to deviation of the tongue towards the effected side

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2217 Cranial Nerves Slides