The Cranial Nerves

Clinical Assessment

The “FACE” of Cranial Nerves

J Carley MSN, MA, CNEFall 2009

1

2 2

3 3

4 45 66 88 910

12

I OlfactoryII OpticIII OculomotorIV TrochlearV Trigeminal

VI AbducensVII FacialVIII AcousticIX Glossopharyngeal

X VagusXI Spinal AccessoryXII Hypoglossal

Cranial Nerves

Cranial NervesWhen assessing the cranial nerves, there are

3 items the examiner must know:

Function (Motor, Sensory, Mixed)TestingSigns of Dysfunction

Cranial Nerves

CN I – Olfactory Nerve Function: special sensory

Testing: Use 2-3 vials of familiar odors Test one nostril at a time with patient’s eyes closed Use least irritating scent first and allow the patient

to rest in between vials Signs of Dysfunction: anosmia

O O O T T A F A G V S H

Cranial Nerves CN II – Optic Nerve

Function: special sensory

Testing: Snellen Eye chart Fundus Exam Visual fields via confrontation Pupillary Light reflex

Signs of Dysfunction Blindness Loss of pupillary constriction (sensory)

O O O T T A F A G V S H

Cranial Nerves

CN III – Occulomotor Nerve Function: somatic & visceral motor

Testing: Six Cardinal Fields of Gaze Pupillary Light reflex: (motor) Accommodation

Signs of Dysfunction: Eye turned down & out w/ ptosis Mydriasis, Loss of accommodation, Diplopia

O O O T T A F A G V S H

Cranial Nerves CN IV – Trochlear Nerve

Function: somatic motor

Testing: Six Cardinal Fields of Gaze

Signs of Dysfunction: Vertical diplopia Excycodeviation of the eye

O O O T T A F A G V S H

Cranial Nerves

CN V – Trigeminal Nerve Function:

Branchial motor – mastication General Sensory – sensory to the face

O O O T T A F A G V S H

Cranial Nerves

CN V – Trigeminal Nerve Testing:

Sharp & light touch over the three divisions Corneal Blink Reflex (sensory) Clinch teeth & Jaw Jerk

Signs of Dysfunction: Weakness Hemianesthesia Absent Corneal Blink Reflex

O O O T T A F A G V S H

Cranial Nerves

CN VI – Abducens Nerve Function: somatic motor Testing:

Six Cardinal Fields of Gaze Signs of Dysfunction:

Horizontal diplopia Medial deviation of the eye

O O O T T A F A G V S H

Cranial Nerves

CN VII – Facial Nerve Function:

Branchial motor – facial muscles Visceral motor – glandular fcn General Sensory – skin of the auricle Special Sensory - taste

O O O T T A F A G V S H

Cranial Nerves

CN VII – Facial Nerve Testing:

Branchial motor component: facial expression Special Sensory: taste to the anterior 2/3 of tongue

Signs of Dysfunction: Hemiparesis Dry eye Lagophthalmos Dry mouth Loss of taste

O O O T T A F A G V S H

Cranial Nerves

CN VIII – Acoustic (Vestibulocochlear) Nerve

Function: special sensory Testing: hearing tests: Rinne, Weber, Audiology,

whisper, fingertips Signs of Dysfunction:

Vertigo Nystagmus Disequilibrium Sensorineural deafness

O O O T T A F A G V S H

Cranial Nerves

CN IX – Glossopharyngeal Nerve

Function: Branchial Motor – elevation of pharynx during

swallowing & speech Visceral Motor – parotid gland fcn Visceral Sensory – communication between carotid

body & sinus General Sensory - tongue Special Sensory - taste

O O O T T A F A G V S H

Cranial Nerves

CN IX – Glossopharyngeal Nerve

Testing:

Branchial Motor: swallowing General Sensory: gag reflex Special sensory: taste of posterior 1/3 of tongue

O O O T T A F A G V S H

Cranial Nerves

CN IX – Glossopharyngeal Nerve

Signs of Dysfunction Dysphagia Dry mouth Loss of taste Loss of gag reflex

TYPICALLY, IX and X are tested together

O O O T T A F A G V S H

Cranial Nerves

CN X – Vagus Nerve Function:

Branchial Motor – deglutition & phonation Visceral Motor – smooth muscles of the thoracic &

abdominal viscera Visceral Sensory – thoracic & abdominal viscera General Sensory – external ear

TYPICALLY, IX and X are tested together

O O O T T A F A G V S H

Cranial Nerves

CN X – Vagus Nerve Testing:

Branchial motor: swallowing, gag reflex, soft palate elevation with uvula remaining while saying “Ah”

Signs of Dysfunction: Dysphagia Hoarseness Uvula deviation

O O O T T A F A G V S H

Cranial Nerves

CN XI – Spinal Accessory Nerve Function: somatic motor Testing: Resisted shoulder elevation & head rotation Signs of Dysfunction:

Atrophy & Weakness Fasciculations Neck or shoulder deviation

O O O T T A F A G V S H

Cranial Nerves

CN XII – Hypoglossal Nerve Function: somatic motor Testing:

Stick out tongue Press tongue against check while palpating to test

muscle strength Articulation of hard consonants: ‘L’, ‘T’, ‘D’, & ‘N’

Signs of Dysfunction: Atrophy & Weakness Deviation Dysarthria

O O O T T A F A G V S H