Cranial Nerves

Clinical Assessment

The “FACE” of Cranial Nerves

I OlfactoryII OpticIII OculomotorIV TrochlearV Trigeminal

VI AbducensVII FacialVIII AcousticIX Glossopharyngeal

X VagusXI Spinal AccessoryXii Hypoglossal

Cranial Nerves

Cranial Nerves

When assessing the cranial nerves, there are 4 items the examiner must know:– Function– Name & Location of Primary Nuclei– Testing– Signs of Dysfunction

Cranial Nerves

CN I – Olfactory Nerve– Function: special sensory– Name & Location of 1o Nuclei: cribriform plate – 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

Cranial Nerves

CN II – Optic Nerve– Function: special sensory– Name & Location of 1o Nuclei: retina– Testing:

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

– Signs of Dysfunction Blindness Loss of pupillary constriction (sensory)

Cranial Nerves

CN III – Occulomotor Nerve– Function: somatic & visceral motor– Name & Location of 1o Nuclei:

Somatic Motor Nucleus: EOM Visceral Motor: pupillary constriction & accommodation

– 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

Cranial Nerves

CN IV – Trochlear Nerve– Function: somatic motor– Name & Location of 1o Nuclei– Testing:

Six Cardinal Fields of Gaze

– Signs of Dysfunction: Vertical diplopia Excycodeviation of the eye

Cranial Nerves

CN V – Trigeminal Nerve– Function:

Branchial motor – mastication General Sensory – sensory to the face

– Name & Location of 1o Nuclei – Motor Sensory

– Mesencephalic Nucleus: proprioception– Pontine Trigeminal Nucleus: touch– Nucleus of Spinal Tract (spinal trigeminal tract): pain & temp

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

Cranial Nerves

CN VI – Abducens Nerve– Function: somatic motor– Name & Location of 1o Nuclei– Testing:

Six Cardinal Fields of Gaze

– Signs of Dysfunction: Horizontal diplopia Medial deviation of the eye

Cranial Nerves

CN VII – Facial Nerve– Function:

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

– Name & Location of 1o Nuclei: Facial Motor Nucleus Superior Salivatory Nucleus Nucleus of Spinal Tract Nucleus Solitarius

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

Cranial Nerves

CN VIII – Acoustic (Vestibulocochlear) Nerve

– Function: special sensory– Name & Location of 1o Nuclei:

Vestibular Nucleus Dorsal & Ventral Cochlear Nucleus

– Testing: hearing tests: Rinne, Weber, Audiology

– Signs of Dysfunction: Vertigo Nystagmus Disequilibrium Sensorineural deafness

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

Cranial Nerves

CN IX – Glossopharyngeal Nerve– Name & Location of 1o Nuclei:

Nucleus Ambiguous Inferior Salivatory Nucleus Nucleus Solitarius Nucleus of Spinal Tract Nucleus Solitarius

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

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

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

Cranial Nerves

CN X – Vagus Nerve– Name & Location of 1o Nuclei:

Nucleus Ambiguous Dorsal Vagal Nucleus Nucleus Solitarius Nucleus of Spinal Tract

– Testing: Branchial motor: swallowing, gag reflex, soft palate elevation with uvula

remaining while saying “Ah”

– Signs of Dysfunction: Dyspagia Hoarsness Uvula deviation

Cranial Nerves

CN XI – Spinal Accessory Nerve– Function: somatic motor– Name & Location of 1o Nuclei– Testing: Resisted shoulder elevation & head rotation

– Signs of Dysfunction: Atrophy & Weakness Fasciculations Neck or shoulder deviation

Cranial Nerves

CN XII – Hypoglossal Nerve– Function: somatic motor– Name & Location of 1o Nuclei– 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