Cranial Nerve Reference Chart

Sensory Nerves: Carry sensory information to the brain

Motor Nerves: Control muscle movement and motor function

Mixed Nerves: Contain both sensory and motor components

Parasympathetic: Autonomic functions (e.g., pupil constriction, salivation, lacrimation)

Clinical Assessment: Systematic evaluation of cranial nerves is essential for neurological examination. Test each nerve individually and document findings carefully for accurate diagnosis.

Functional Overlap Note: Some cranial nerves carry mixed functions (e.g., CN V has both sensory and motor branches), and dysfunction may affect one or both components independently.

Cranial Nerve	Type(s)	Functions	Associated Dysfunctions
Olfactory Cranial Nerve I Cribriform plate → Olfactory bulb	Sensory Test: Identify familiar scents	Sense of smell (olfaction) Contributes to taste perception Unlike other sensory systems, olfactory input bypasses the thalamus and projects directly to the piriform cortex, amygdala, and entorhinal cortex	Unilateral or bilateral loss of sense of smell (anosmia) Reduced taste perception (due to olfactory loss) Hyposmia (reduced smell)
Optic Cranial Nerve II Retina → Optic chiasm → Visual cortex	Sensory Test: Visual acuity, visual fields	Vision and visual perception Light detection and processing Pupillary light reflex (afferent) Visual input relayed through lateral geniculate nucleus (LGN) of thalamus to primary visual cortex in the occipital lobe (Brodmann area 17)	Loss of vision (blindness) Visual field defects Decreased visual acuity Papilledema (optic disc swelling)
Oculomotor Cranial Nerve III Midbrain → Superior orbital fissure	Motor Parasympathetic Test: Eye movements, pupil response	Movement of eyeball (most extraocular muscles) Upper eyelid elevation (levator palpebrae) Pupil constriction (via ciliary ganglion) Lens accommodation	Eye movement problems (diplopia) Ptosis (drooping eyelid) Pupil dilation (mydriasis) Loss of accommodation
Trochlear Cranial Nerve IV Midbrain → Superior orbital fissure	Motor Test: Downward and inward eye movement	Movement of eyeball (superior oblique muscle) Downward and inward eye rotation Due to its long intracranial course and dorsal emergence, CN IV is highly susceptible to injury	Eye movement problems Diplopia (especially looking down) Head tilt compensation
Trigeminal Cranial Nerve V Pons → Three divisions (V1, V2, V3)	Sensory Motor Test: Facial sensation, jaw movement	General sensation in face, scalp, corneas Nasal and oral cavity sensation Chewing (muscles of mastication) Jaw clenching and lateral movement	Loss of facial sensation (numbness) Trigeminal neuralgia (severe facial pain) Loss of corneal reflex Difficulty chewing Jaw deviation
Abducens Cranial Nerve VI Pons → Superior orbital fissure	Motor Test: Lateral eye movement	Movement of eyeball (lateral rectus muscle) Outward (lateral) eye movement Long intracranial course; sensitive to increased ICP	Eye movement problems Inability to abduct eye laterally Diplopia (horizontal) Esotropia (inward eye deviation)
Facial Cranial Nerve VII Pons → Internal auditory canal → Stylomastoid foramen	Sensory Motor Parasympathetic Test: Facial expressions, taste	Taste (anterior 2/3 of tongue) Facial expression (muscles of facial expression) Lacrimation and salivation (via pterygopalatine and submandibular ganglia) Stapedius muscle (hearing protection)	Loss of taste (anterior tongue) Inability to close eye (lagophthalmos) Facial droop/asymmetry Dry eye and mouth Hyperacusis (sound sensitivity)
Vestibulocochlear Cranial Nerve VIII Inner ear → Internal auditory canal → Brainstem	Sensory Test: Hearing tests, balance assessment	Hearing (cochlear division) Balance and equilibrium (vestibular division) Spatial orientation Head position sensing Cochlear branch: hearing; Vestibular branch: balance and spatial orientation	Loss of hearing (sensorineural deafness) Balance problems and vertigo Nystagmus Tinnitus (ringing in ears)
Glossopharyngeal Cranial Nerve IX Medulla → Jugular foramen	Sensory Motor Parasympathetic Test: Gag reflex, swallowing	Taste and sensation from posterior tongue Swallowing (stylopharyngeus muscle) Speech articulation Parotid salivation (via otic ganglion) Carotid body/sinus monitoring	Inability to swallow (dysphagia) Hoarse voice Loss of gag reflex Loss of taste (posterior tongue) Dry mouth
Vagus Cranial Nerve X Medulla → Jugular foramen → Widespread distribution	Sensory Motor Parasympathetic Test: Voice, swallowing, gag reflex	Taste and sensation from epiglottis and pharynx Swallowing and speech Viscera regulation (heart, lungs, GI tract to splenic flexure) Heart rate and digestive regulation Digestive fluid secretion	Inability to swallow (dysphagia) Hoarse voice or vocal cord paralysis Delayed gastric emptying Cardiac arrhythmias Loss of gag reflex
Accessory Cranial Nerve XI Medulla/Spinal cord → Jugular foramen	Motor Test: Head turning, shoulder shrug	Head and shoulder movement Sternocleidomastoid muscle (head turning) Trapezius muscle (shoulder elevation) Neck stabilization	Inability to move head and raise shoulders Weakness turning head to opposite side Shoulder droop Neck muscle atrophy
Hypoglossal Cranial Nerve XII Medulla → Hypoglossal canal	Motor Test: Tongue movement, speech	Movement of tongue muscles Speech articulation Swallowing assistance Food manipulation in mouth	Inability to move tongue Tongue deviation (toward lesion side) Difficulty with speech (dysarthria) Difficulty swallowing Tongue atrophy and fasciculations

Clinical Mnemonics and Testing Guidelines

Cranial Nerve Names (Traditional)

"Oh, Oh, Oh, To Touch And Feel Very Good Velvet, Ah Heaven"
Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory, Hypoglossal

Cranial Nerve Functions

"Some Say Marry Money, But My Brother Says Big Brains Matter More"
Sensory, Sensory, Motor, Motor, Both, Motor, Both, Sensory, Both, Both, Motor, Motor

Eye Movement Testing

H-Pattern Testing: Test all directions of gaze in an "H" pattern to assess CN III, IV, and VI function systematically. Note any diplopia, nystagmus, or restricted movement.

Facial Nerve Testing

Seven Functions: Facial expression, taste (anterior 2/3 tongue), lacrimation, salivation, stapedius reflex, sensation (small area), and corneal reflex contribution.

Trigeminal Divisions

V1 (Ophthalmic): Forehead and upper eyelid
V2 (Maxillary): Cheek and upper lip
V3 (Mandibular): Jaw and lower lip + motor to jaw muscles

Rapid Screening

Quick Assessment: Visual acuity (II), eye movements (III,IV,VI), facial sensation and strength (V,VII), hearing (VIII), speech and swallowing (IX,X,XII), shoulder shrug (XI).

Urgent Neuro-Ophthalmologic Signs

"Down and Out" Eye: CN III palsy - eye looks down and outward with ptosis and dilated pupil
Bell's Palsy: CN VII - inability to close eye, facial droop, loss of forehead wrinkles
Jaw Deviation: CN V motor - jaw deviates toward the side of lesion when opening mouth

Disclaimer: This chart is provided for educational purposes only and is not intended to replace a neurological examination, diagnostic imaging, or consultation with a qualified medical professional. Cranial nerve evaluation requires individualized clinical assessment within the context of each patient's symptoms and history. PsychConcierge PLLC ("PsychConcierge.com") makes no guarantees regarding the completeness or clinical applicability of this information for any specific case and disclaims all liability for outcomes associated with reliance on this content.

Cranial Nerve Functions and Dysfunctions

Clinical Mnemonics and Testing Guidelines