cranial nerves

first cranial nerve

olfactory

types of fibers in olfactory nerves

special sensory (afferent)

function of olfactory nerves

smell or olfaction

origin of olfactory nerves

nasal cavity

olfactory system consists of

olfactory epithelium, bulbs and tracts along with olfactory areas of the brain

effect of damage of olfactory nerve

impaired sense of smell / anosmia

clinical test to determine if there’s olfactory nerve damage

determine whether subject can smell aromatic substance

 olfactory fibers cross the skull base through the

the olfactory foramina of the cribriform plate

2nd cranial nerve

optic nerve

types of fibers of optic nerve

somatic sensory

optic nerve function

vision

origin of optic nerve

retina

termination of optic nerve

thalamus

 optic nerve fibers cross the skull base through the

optic canal

effect of damage to optic nerve

blindness in part or all of the visual field

clinical test to determine if there’s damage to optic nerve

* inspect retina with ophthalmoscope
* test visual fields and visual acuity

3rd cranial nerve

oculomotor

type of fibers in oculomotor

mainly somatic motor with parasympathetic fibers

function of oculomotor nerve

eye movements, elevation of eyelids, constriction of pupil and focusing

origin of oculomotor

midbrain

termination of somatic fibers of oculomotor

* levator palpebrae superioris muscle
* superior rectus muscle
* inferior rectus muscle
* medial rectus muscle
* inferior oblique muscle

termination of parasympathetic fibers of oculomotor nerve

* constrictor pupillae
* ciliary muscle

oculomotor nerve enters orbit via

superior orbital fissure

oculomotor nerve branches

superior and inferior division

effects of damage to oculomotor nerve

* drooping of eyelids
* dilated pupils
* inability to move eyes in certain directions
* tendency of eye to rotate laterally at rest
* double vision
* difficulty focusing

clinical tests for damage of oculomotor nerve

* look for differences in size and shape of right and left pupils
* test pupillary response to light
* test ability to track moving objects
* test raising the upper eyelid

4th cranial nerve

trochlear nerve

types of fibers of trochlear nerve

pure motor somatic fibers

function of trochlear nerve

eye movements

origin of trochlear nerve

midbrain (back)

termination of trochlear nerve

superior oblique muscle

cranial course of trochlear nerve

superior orbital fissure

trochlear nerve exits brain

dorsally

effects of damage of trochlear nerve

* double vision and inability to rotate eye inferolaterally
* eye points superolaterally and patient often tilts head towards affected side

clinical test for trochlear nerve damage

test ability to rotate eye inferolaterally

6th cranial nerve

abducens nerve

types of fibers of abducens nerve

pure motor / somatic

function of abducens nerve

eye movements

origin of abducens nerve

inferior pons

termination of abducens nerve

lateral rectus muscle

cranial course of abducens nerve

superior orbital fissure

effect of damage of abducens nerve

* at rest affected eye is fixed medially
* inability to rotate eye laterally

clinical test for damaged abducens nerve

test lateral eye movements

5th cranial nerve

trigeminal

nuclei of trigeminal nerve

1 motor and 3 sensory nuclei

sensory nuclei of trigeminal

* mesencephalic nucleus
* pontine trigeminal
* spinal trigeminal nucleus

mesencephalic nucleus is responsible for

proprioceptive fibers

pontine trigeminal nucleus is responsible for

touch and pressure fibers

spinal trigeminal nucleus is responsible for

pain and temperature fibers

divisions of trigeminal nerve

* ophthalmic V1
* maxillary V2
* mandibular V3

types of fibers in V1

pure sensory

function of v1

main sensory nerve of upper face, pain temperature and touch

origin of V1

superior region of face, surface of eyeball, tear gland, superior nasal mucosa, frontal and ethmoid air sinuses

termination of V1

pons

cranial course of V1

superior orbital fissure

branches of V1

lacrimal, frontal and nasociliary nerves

effect of damage of V1

loss of sensation of the upper face

clinical test for V1 damage

test the corneal reflex (blinking in response to light touch to eyeball)

types of fibers of V2

pure sensory

function of V2

main sensory nerve of middle face, pain temperature and touch

origin of V2

Middle region of face, nasal mucosa, maxillary air sinus, palate, upper teeth & gums

termination of V2

pons

cranial course of V2

foramen rotundum then infraorbital foramen

effects of damage of V2

loss of sensation of middle face

clinical test for V2 damage

test sense of touch, pain, and temperature with light touch, pinpricks and hot & cold objects

regions where maxillary nerve passes

* cranial cavity
* pterygopalatine fossa
* infratemporal fossa
* infraorbital canal and foramen
* face

branches of V2 maxillary nerve

* Superior alveolar nerve (anterior, posterior and middle)
* Middle meningeal nerve
* Infraorbital nerve
* Zygomatic nerve
* Inferior palpebral nerve
* Superior labial nerve
* Pharyngeal nerve
* Greater and lesser palatine nerves
* Nasopalatine nerve

Post ganglionic fibres from the pterygopalatine ganglion (derived from the facial nerve) travel **with** the maxillary nerve to:

* Lacrimal gland
* Mucous glands of the nasal mucosa

type of fibers V3 mandibular nerve

mixed, motor and sensory

function of V3

innervates muscles of mastication and main sensory nerve of lower face, pain temperature and touch

sensory origin of V3

inferior region of face, anterior 2/3rd of tongue, lower teeth & gums, floor of mouth, dura mater

sensory termination of V3

pons

motor origin of V3

pons (motor nucleus)

motor termination of V3

* 4 muscles of mastication (masseter, temporalis, 2 pterygoids)
* 2 tensors (tensor palatini and tensor tympani in middle ear)
* anterior belly of digastric
* mylohyoid

7th cranial nerve

facial nerve

types of fibers of facial nerve

mixed (motor & sensory) and parasympathetic

function of facial nerve

**Major motor N. of facial expression**, autonomic control of lacrimal glands, nasal and palatine glands, submandibular & sublingual salivary glands and sense of taste

sensory origin of facial nerve

taste buds on anterior 2/3 of tongue and palate

sensory termination of facial nerve

pons

motor origin of facial nerve

pons

motor termination of facial nerve

divides into temporal, zygomatic, buccal, mandibular & cervical branches

***Somatic motor f*****ibers of facial nerve** end on

digastric muscle, stapedius muscle of middle ear & muscle of facial expression

parasympathetic fibers of facial nerve end on

submandibular, sublingual salivary glands and lacrimal glands

branches of facial nerve

* greater petrosal nerve
* nerve to stapedius
* chorda tympani
* nerve to posterior belly of digastric muscle
* nerve to stylohyoid muscle
* posterior auricular nerve
* 5 terminal branches to the muscles of scalp, face & platysma, through Temporal, zygomatic, buccal, mandibular and cervical branches

cranial course of facial nerve

internal auditory meatus then facial canal then stylomastoid foramen

effects of damage to facial nerve

* inability to control facial muscle
* sagging resulting from loss of muscle tone (bell’s palsy)
* distorted sense of taste especially sweets

clinical tests for damage of facial nerve

* test anterior 2/3rd of tongue with sugar, salt, vinegar
* test response of tear glands to amonia fumes
* test motor function by asking subject to close eyes , smile, whistle, frown, raise eyebrows

type of fibers of glossopharyngeal nerve

mixed and parasympathetic

function of glossopharyngeal

* swallowing
* salivation
* gagging
* regulation of blood pressure and respiration
* general and taste sensations from posterior 1/3 of tongue to pharynx

sensory origin of glossopharyngeal nerve

Pharynx, middle ear, posterior 1/3 of tongue, (including taste buds), internal carotid arteries

9th cranial nerve

glossopharyngeal

sensory termination of glossopharyngeal nerve

medulla oblongata

motor origin of glossopharyngeal nerve

medulla oblongata

motor termination of glossopharyngeal nerve

parotid salivary gland, glands of posterior tongue, and stylopharyngeus muscle

branches of glossopharyngeal nerve

* meningeal branch
* tympanic branch
* nerve to stylopharyngeus
* carotid sinus nerve
* pharyngeal branches
* tonsillar branches
* terminal lingual branches

facial nerve nuclei

* nucleus of superior salivatory nerve
* motor nucleus of seventh nerve
* nucleus of fascia solitarius

cranial course of glossopharyngeal nerve

jugular foramen

effects of damage of glossopharyngeal nerve

* loss of bitter and sour taste
* impaired swallowing

clinical test for damage of glossopharyngeal nerve

* Test gag reflex, swallowing, and coughing.
* Test the taste sensation of posterior 1/3 of tongue using bitter and sour substances.

10th cranial nerve

vagus