Cranial Nerve Assessment — Week 2 (Internship 2)

Vocabulary flashcards covering cranial nerves, their functions, tests, and common abnormal findings from Week 2 notes.

Olfactory nerve (CN I)

Sensory nerve for smell; olfactory bulb at the cribriform plate; first CN to lose function after brain injury; anosmia.

Anosmia

Inability to detect odors; often due to olfactory nerve/frontal lobe issues.

Foster Kennedy syndrome

Olfactory groove/sphenoid ridge mass causing ipsilateral anosmia, ipsilateral optic atrophy, and contralateral papilledema.

Optic nerve (CN II)

Sensory nerve for vision; retina contains cones (day/color) and rods (night).

Cones

Retinal cells responsible for daylight and color vision.

Rods

Retinal cells responsible for night vision.

Nyctalopia

Night blindness; often due to rod dysfunction or vitamin A deficiency.

Vitamin A (retinol)

Fat-soluble vitamin essential for photoreceptor function; deficiency can cause Nyctalopia.

Snellen chart

Visual acuity test; normal is 20/20; 20/200 denotes legal blindness.

20/20 vision

Normal visual acuity at 20 feet.

20/200 vision

Legal blindness; significantly reduced distance vision.

Visual field by confrontation

Peripheral vision test comparing each eye's field of view.

Anisocoria

Unequal pupil sizes.

Pupillary light reflex

Afferent limb (CN II) detects light; efferent limb (CN III) constricts pupil.

PERRL

Pupils Equal, Round, Reacting to Light.

PERRLA

Pupils Equal, Round, Reacting to Light and Accommodation.

Monocular blindness

Loss of vision in one eye due to optic nerve/retina pathology.

Bitemporal hemianopia

Loss of outer visual fields in both eyes from optic chiasm lesion.

Homonymous hemianopia

Loss of the same visual field in both eyes; lesion posterior to chiasm.

Optic chiasm

Crossing of nasal retinal fibers; lesion leads to binasal/temporal field defects.

Vestibulocochlear nerve (CN VIII)

Sensory nerve for hearing (cochlear) and balance (vestibular).

VOR (vestibulo-ocular reflex)

Eye movements stabilizing vision during head movements; tests vestibular function.

Vertigo

Spinning dizziness due to vestibular system disturbance.

Deafness

Hearing loss; types include conductive, sensorineural, and cortical.

Weber test

Tuning fork test; lateralizes to affected ear in conductive loss; to better ear in sensorineural loss.

Rinne test

Air conduction vs. bone conduction test; normally AC > BC; reversed in conductive loss.

Schwabach test

Comparative bone conduction test between patient and examiner.

Glossopharyngeal nerve (CN IX)

Mixed nerve; taste posterior 1/3 of tongue; sensation in oropharynx; motor to stylopharyngeus; parotid gland; afferent gag reflex.

Posterior tongue taste

Bitter and sour tastes on the posterior third of the tongue.

Gag reflex

Afferent limb CN IX; efferent limb CN X; elicited by posterior pharynx stimulation.

Vagus nerve (CN X)

Mixed nerve; motor to pharynx and larynx; sensory to ear; autonomic to thorax/abdomen.

Uvula deviation

LMN lesion: uvula deviates away from lesion; LMN/CVA distinction: deviation toward the stronger side.

Dysphonia

Hoarseness indicating vocal cord or laryngeal nerve involvement.

Trigeminal nerve (CN V)

Mixed nerve with V1, V2, V3 divisions; sensory face and cornea; motor muscles of mastication; jaw jerk.

Gasserian ganglion

Trigeminal (semilunar) ganglion containing sensory neuron cell bodies.

Mesencephalic nucleus

Trigeminal nucleus for proprioception of the face.

Trigeminal neuralgia

Tic douloureux; sudden, severe facial pain due to trigeminal nerve dysfunction.

Corneal reflex

Afferent limb CN V1; efferent limb CN VII; blink response to corneal touch.

Jaw jerk reflex

Masseter reflex tested via tapping the chin; CN V integrity.

Masseter, temporalis, medial pterygoid

Muscles of mastication responsible for closing the jaw.

Facial nerve (CN VII)

Mixed nerve; motor muscles of facial expression; sensory anterior 2/3 tongue; autonomic lacrimal and salivary glands; stapedius.

Nervus intermedius

Part of CN VII carrying sensory and autonomic fibers; motor component is facial nerve proper.

Bell’s palsy

Peripheral CN VII palsy with unilateral facial weakness; forehead involvement common.

Central facial palsy

Stroke-related CN VII palsy with forehead sparing due to bilateral innervation.

Oculomotor nerve (CN III)

Motor to most extraocular muscles; elevates eyelid; constricts pupil; accommodates lens.

Ptosis

Drooping eyelid from levator palpebrae superioris weakness (CN III).

Pupillary constriction and accommodation

CN III-mediated pupil constriction and lens accommodation.

Trochlear nerve (CN IV)

Motor to the superior oblique; moves eye down and in; intorsion.

Superior oblique

Eye muscle controlled by CN IV responsible for downward/inward movement and intorsion.

Abducens nerve (CN VI)

Motor to lateral rectus; abducts the eye; long intracranial course.

Lateral rectus

Eye muscle abducting the pupil; innervated by CN VI.

Esotropia

Inward turning of the eye; can result from CN VI palsy.

Exotropia

Outward turning of the eye; can result from CN III/V involvement.

Spinal accessory nerve (CN XI)

Motor to trapezius and sternocleidomastoid; weakness causes inability to shrug.

Hypoglossal nerve (CN XII)

Motor to tongue; tongue movements and shaping.

Dysarthria

Difficulty articulating speech; can involve CN X or XII.

Oscillopsia

Perception of oscillating vision; often from vestibulo-ocular or vestibular problems.

Argyll-Robertson pupil

Small irregular pupil that reacts to accommodation but not light; associated with syphilis.