Cranial Nerves

Cranial Nerves I and II

cranial nerves that emerge from the brain itself.

Cranial Nerves III and IV

cranial nerves that emerge at the level of the midbrain.

Cranial Nerves V, VI, VII, and VIII

cranial nerves that emerge at the level of the pons.

Cranial Nerves IX, X, XI, and XII

cranial nerve that emerge at the level of the medulla oblongata.

General Somatic Afferent

for general sensations.

Special Somatic Afferent

for hearing, balance, and vision.

General Viseral Afferent

for viscera; sensation of the internal organs.

Special Visceral Afferent

for smell, taste.

General Somatic Efferent

for somatic striated muscle.

General Visceral Efferent

for glands and smooth muscles; parasympathetic innervation.

Special Visceral Efferent

for branchial arch striated muscles.

Olfactory Bulb

\- located above the cribriform plate at the ethmoid bone

\- contains follicles where sensory input travels from the mucosa of the nose

Secondary Olfactory Area

\- at the hippocampal gyrus

\- have the ability to store different emotional reactions to the specific olfactory sensations that one perceives

• Mitral Cell

• Tufted Cell

• Granular Cell

cells in the olfactory bulb.

Synaptic Glomeruli

penetrates in the cribriform plate of the ethmoid bone and synapses with the cells in the olfactory bulb to transfer olfactory sensation from the receptor to the bulb itself and to the olfactory tract.

Olfactory Tract

divided into the medial and lateral stria.

• Periamygdaloid

• Prepiriform

• Etorhinal Area

division of lateral stria of the olfactory tract.

Periamygdaloid and Prepiriform

subserves the primary olfactory area.

Entorhinal Area

subserves the secondary olfactory area.

Olfactory nerve

its main function is the sense of smell.

• Test for sense of smell using common and non irritating odor

• It should be assessed one at a time

test for olfactory nerve.

Anosmia

\- inability to differentiate specific scent

\- frontal lobe lesion

\- seen most commonly when there is a traumatic injury (coup-contrecoup injury)

\- may be ipsilateral or bilateral

• Black Eye

• Rhinorrhea

occurs when there is a frontal bone fracture.

Rhinorrhea

\- leak of CSF in cavernous sinus; sweet in taste

\- may also be pinkish due to blood

Presbyopia

blurred vision due to old age.

Visual Agnosia

secondary visual cortex.

True Blindness

affected is the primary visual cortex.

Optic Nerve

\- pure sensory cranial nerve

\- function is for vision alone

• Visual Acuity Test

• Visual Eye Field Test

• Test Pupillary Reaction to Light

• Test for Accommodation

• Pupillary Light Reflex

test for optic nerve.

Snellen Chart

standard test used for visual acuity test.

20/200

what reading considered legally blind.

• Central

• Peripheral

common visual eye field can be divided into these:

Oculomotor Nerve

cranial nerve for automatic pupillary constriction.

Pupillary Reaction to Light

purpose of this test is to know if pt can see the light.

Test of Accommodation

patient’s eye constricts as the object approaches the eye.

• Pretectal Nucleus

• Edinger Westphal

two nucleus concerned for pupillary light reflex.

Direct Light Reflex

constriction of the ipsilateral pupil; adjacent to the stimuli.

Consensual Light Reflex

constriction of the contralateral pupil; opposite to the stimuli.

T

T/F if the optic nerve is affected, both the (L) and (R) direct and consensual light reflex is affected.

Argyll Robertson Pupil

\- (+) pupil constriction to accommodation

\- (-) pupil constriction to light reflex

Anisocoria

unequal pupillary constriction.

Oculomotor Nerve

- pure motor

- two motor nuclei:

• Main motor nuclei/somatic - voluntary

• Accessory parasympathetic nucleus/parasympathetic - involuntary

- turns the eye up, down, and in and elevates the eyelid

- subserves all the extraocular muscles except for superior oblique and lateral rectus

External Strabismus

\- exotropia

\- lateral deviation of the eyeball

Ptosis

drooping of the upper eyelid.

• Eye Pursuit

• Pupillary Size and Shape

• Pupillary Reflex

tests for oculomotor nerve.

Cranial Nerves III, IV, and IV

cranial nerves concerned for visual tracking.

Trochlear Nerve

\- the most slender of the cranial nerves and the only one to leave the posterior surface of the brainstem

\- turns adducted eye down

\- subserves superior oblique

* Eye Pursuit

test for trochlear nerve.

Vertical Diplopia

\- has to tilt the head in order to align the eyes

\- cannot turn eyes downward and inward

\- pt looks upward; only inferior oblique moves

Superior Oblique

when this muscle is affected the patient has great difficulty in turning the eye downward and laterally.

Trigeminal Nerve

- mixed; sensory and motor

- motor:

• muscles of mastication

• tensor tympani

• tensor veli palatini

• mylohyoid

• anterior belly of the digastric muscle

- sensory:

• sensations of face

• sensation of the mouth and tongue

• sensation of the cornea (test: corneal reflex)

• Opthalmic

• Maxillary

• Mandibular

three branches of the trigeminal nerve.

Opthalmic

\- sensory fibers only and exits at the superior orbital fissure

\- subserves upper portion, most of the forehead to the nose

Maxillary

\- sensory fibers only and exits at the foramen rotundum

\- subserves upper lip

Mandibular

\- sensory and motor fibers; exits at foramen ovale

\- subserves lower lip and jaw

Tensor Tympani

muscles that is subserved by the trigeminal nerve that regulates the amount of sound that enters the ear.

• Clenching teeth

• Test for superficial sensation

• Corneal Reflex

tests for trigeminal nerve.

Trigeminal Neuralgia

\- tic douloureux

\- abnormal pain sensation on the trigeminal nerve distribution (commonly: V2 and V3)

Cranial Nerves V and VII

cranial nerves that is concerned with corneal reflex.

Abducens Nerve

\- longest intracranial nerve

\- responsible in giving motor control to lateral rectus

Internal Strabismus

\- esotropia

\- medial deviation of the eyeball

• Eye Position

• Eye Pursuit

test for abducens nerve.

Facial Nerve

\- mixed type of nerve

\- controls muscle of facial expression, stapedius muscle, and digastric muscle

\- parasympathetic: salivary and lacrimal glands

\- visceral: anterior 2/3 of the tongue

\- somatic: small region of the external ear

• Temporal

• Zygomatic

• Buccal

• Marginal Mandibular

• Cervical

divisions of the facial nerve.

• Stylomastoid Foramen

• Chorda Tympani

• Stapedius

• Geniculate Ganglion

• Internal Auditory Meatus

• Pons

areas wherein the facial nerve travels/go through.

Nervus Intermedius

division of the facial nerve concerned with parasympathetic functions (salivary and lacrimal).

Hyperacusis

\- increased sensitivity to sounds

\- can be unilateral or bilateral

Hemifacial Paralysis

\- due to paralysis/weakness of the muscles if facial expression

\- accumulation of saliva

Non noxious stimuli in the front of the tongue

test for taste sensation of facial nerve.

• Vestibular

• Cochlear

two components of the vestibulocochlear.

• Balance

• Eye head coordination

test for vestibular.

Sensory Neural Deafness

occurs when there is a problem within the cochlea or the neural pathway to the auditory cortex.

Conduction Deafness

occurs when sound is impeded through the external ear, the middle ear, or both.

Rinne’s Test

used to differentiate bone and air conduction.

Bone Conduction

sound travel via bone.

Air Conduction

sound travel via air.

Weber’s Test

used to test bone conduction alone.

Whispered Voice Test or Ticking Watch Test

alternative test if there is no tuning fork.

Schwabach Test

\- lest sensitivity; not commonly used

\- alternate placing of the tuning fork on the mastoid process of both pt and PT

Glossopharyngeal Nerve

=largest motor component: stylopharyngeus

- parasympathetic: parotid glands

- somatic: middle ear

- visceral sensory:

• special: posterior 1/3 of the tongue

• general chemoreceptors and baroreceptors of carotid body

Nucleus Solitarius

- gustatory nuclei/cardiorespiratory nucleus

- nuclei which orginate branch of glossopharyngeal nerve that supplies chemoreceptors and baroreceptors

- divided into:

• caudal - cardiorespiratory nucleus

• rostral - gustatory nucleus (posterior 1/3 of the tongue)

Vagus Nerve

\- one of the longest cranial nerve; has lot of visceral functions

\- general sensation: external ear

\- responsible parasympathetic and sympathetic of visceral organ and movement of uvula

\- motor for gag reflex

\- least likely to be injured; once it is injured, it can be life threathening

Levator Veli Palatini

muscle that moves the uvula.

\- Patient’s Voice

\- Patient’s Swallowing

\- Movements of the soft palate and the pharynx

\- Gag Reflex

test for vagus nerve.

Accessory Nerve

subserves trapezius and SCM

Examine muscle bulk and strength of trapezius and SCM

test for accessory nerve.

Hypoglossal Nerve

controls voluntary pushing motion of the tongue and retraction.

• Patient’s articulation

• Resting position of tongue

• Tongue movements

test for hypoglossal nerve.

• Dysarthria

• Hemiatrophy of the tongue

• Fasciculation of the tongue

signs that there is a problem with hypoglossal nerve.