Page 1084 - Small Animal Internal Medicine, 6th Edition

1056 PART IX Nervous System and Neuromuscular Disorders

TABLE 58.5
VetBooks.ir Regional Assessment of Cranial Nerves SENSORY INPUT MOTOR FUNCTION

ACTION
CRANIAL NERVE TEST
Menace response Threatening gesture towards CN2—optic nerve CN7—facial nerve
eye; results in a blink
Palpebral reflex Touching medial or lateral CN5—trigeminal nerve CN7—facial nerve
canthus of eye results in blink medial: ophthalmic branch
lateral: maxillary branch
Pupillary light reflex Shining a light in the eye elicits CN2—optic nerve CN3—oculomotor nerve
pupillary constriction (parasympathetic)
Examine for head tilt Evaluate head position CN8—vestibulocochlear —
Vestibulo-ocular reflex Move head from side to side CN8—vestibulocochlear CN3—oculomotor nerve
and dorsoventrally, evaluating CN4—trochlear nerve
for normal eye movements CN6—abducent nerve
and strabismus
Positional nystagmus Flip animal on back and observe CN8—vestibulocochlear —
Facial sensation eyes for nystagmus CN5—trigeminal nerve —
Palpebral response
Pinch lip
Insert hemostat in nose to
stimulate nasal septal mucosa
Jaw tone Assess jaw tone and ability to CN5—trigeminal nerve CN5—trigeminal nerve
close the mouth (mandibular branch)
Facial symmetry Examine for facial symmetry, CN2—optic nerve (menace) CN7—facial nerve
ability to blink, twitch lip, and CN5—trigeminal nerve
move ears (palpebral, corneal reflex,
lip pinch)
Gag reflex Manual stimulation of the CN9—glossopharyngeal CN9—glossopharyngeal nerve
Eat, drink pharynx induces contraction CN10—vagus nerve CN10—vagus nerve
Observe swallowing
Tongue evaluation Inspect the tongue for symmetry, CN5—trigeminal nerve CN12—hypoglossal nerve
observe tongue movements CN7—facial nerve
during eating and drinking CN12—hypoglossal nerve

A B

FIG 58.22
Evaluating the menace response, vision, and pupils. (A) Assess the menace response by
making a menacing gesture toward the eye. (B) Shine a light in the eye to assess
pupillary light reflexes.