Topic 12: Cranial Nerves - Part 1 & 2

True

T or F: Cranial Nerves NEVER cross except for CN IV - clinical findings are on the same sides as the nerve impacted

bilateral innervation

Cranial motor nuclei (lower motor neurons) recieve what kind of innervation from the primary motor cortex

• Exception: lower face CN VII & Tongue CN XII

contralateral

What type of innervation does the lower face CN VII receive from the motor cortex?

contralateral

Which innervation is stronger (contralateral or bilateral) for the Tongue CN XII

olfactory nerves

CN I: sensory only

• Sensory: smell

• Function: carry info from nasal mucosa to olfactory bulb and terminate in temporal lobe (pyriform cortex)

olfactory nerve lesion

CN Lesion: ipsilateral, impaired sense of smell

optic nerves

CN II: sensory only

• Sensory: vision

• Originates: from cerebral cortex

• Part of the Visual Pathway - receives message from the eye and sends to lateral geniculate nucleus

visual feild

In what field are images on the left side seen by both eyes but only processed by the contralateral visual cortex

• message crosses at optic chiasm

monocular blindness

Type of Lesion in the Optic Nerve CN II: damage at the point of the optic nerve between the eye and optic chiasm

• blindness in that one eye

• the other eye remains functional and views most of visual feild

bitemporal hemianopsia

Type of Lesion in the Optic Nerve CN III: pathology of the optic chiasm

• loss of vision in the temporal visual field for BOTH eyes

• Tunnel vision - can only see though nasal fields

homonymous hemianopsia

Type of Lesion in the Optic Nerve CN III: lesion in the optic tract

• loss of vision in the same visual field of both eyes

• ex: damage to right temporal and right nasal field

oculomotor nerve

CN III - motor vision

• Originates in midbrain

• Lesion: ipsilateral, paralyzed eyelid, lateral deviated eye

• Eye goes down and out

trochlear nerve

CN IV - motor vision

• Originates in midbrain

• Lesion: contralateral, impaired downward gaze

• Eye shows upwards and outward deviation

abducens nerve

CN VI - motor vision

• Originates from pons

• Lesion: ipsilateral, partial ocular paralysis w/ medially fixed eye

• Eye is cross-eyed

trigeminal nerves

CN V: motor & sensory

• Originates: pons

• Contains 3 main nerves

trigeminal nerves

CN that has motor functions: mastication

trigeminal nerves

CN that has sensory functions: face, oral and nasal cavity, teeth, gums, eyeballs

opthalmic nerve

One of the main 3 Trigeminal Nerves:

Sensory Functions: forehead, eyeball, upper eyelid, nose

maxillary nerve

One of the main 3 Trigeminal Nerves:

Sensory functions: nose, upper cheeks, lower eyelid, upper gum and teeth, soft and hard palates

mandibular nerve

One of the main 3 Trigeminal Nerves:

Sensory & Motor: jaw, lower gum and teeth

trigeminal nerve lesion

CN Lesion: ipsilateral

• Motor: (LMN) paralysis of jaw, jaw deviates to side of injury

• Sensory: loss of facial sensation