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
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