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SCOTT.LEHBAUER@LETHBRIDGECOLLEGE.AB.CA
Cranial Nerves
Cranial Nerves
Cranial nerves are nerves that originate in the cranium
There are 12 pairs of cranial nervesThe first two pairs attach to the forebrain The others originate in the brain stem
Cranial Nerves
I – Olfactory Nerve
FUNCTIONPurely sensory
nerveCarries afferent
impulses for the sense of smell
TEST smell bilaterally
Olfactory Nerve (83)
II – Optic Nerve
FUNCTIONPurely sensoryCarry afferent
impulses for vision
TEST See bilaterally Optic Nerve (84)
III – Oculomotor Nerve
FUNCTIONChiefly motor nerveCause pupil
constrictionEye movement
TEST Pupil contraction
when light is shined into eye Oculomotor Nerve (85)
IV – Trochlear Nerve
FUNCTIONPrimarily motor
nervesCause eye
movement in one of the extrinsic eye muscles (Superior oblique)
TESTTracking of eye from
left to right
Trochlear Nerve (86)
V – Trigeminal Nerve (The largest Cranial Nerve)
FUNCTION Mixed nerve Provides sensory
and motor input for the face and associated structures
TEST Sensation on three
sections of the face bilaterally
Trigeminal Nerve (87)
VI – Abducens Nerve
FUNCTIONMotor nerveSupplies motor
fibers to the lateral rectus muscles which move the eye
TEST eye tracking from
left to right Abducens (88)
VII – Facial Nerve
FUNCTIONMixed nerve the chief motor
nerve for the muscles of the face
TEST Wrinkle foreheadClose eyesmile Facial Nerve (89)
Bell’s Palsy
Is characterized by paralysis of the face muscles on the affected side and partial loss of taste sensation.
The lower eyelid droops, corner of the mouth sags, tears may continuously drip from eye to eye
These symptoms are caused by damage to the facial nerve
VIII – Auditory Nerve
FUNCTIONMostly sensory,
some motorBranches transmit
the afferent fibers affecting the sense of equilibrium and hearing
TEST Bilateral hearingBalance with your
eyes closedAuditory Nerve (90)
IX – Glossopharyngeal Nerve
FUNCTIONMixed nerveProvides motor
fibers to the muscles of the tongue and pharynx
TEST Gag reflex Glossopharyngeal Nerve (91)
X – Vagus Nerve
FUNCTION Mixed nerve Motor fibers supply
heart, lungs and abdominal viscera
Regulates heart rate, breathing rate and digestive system activity
TEST Say “Ah” uvula is
midline Swallow
Vagus Nerve (92)
XI – Spinal Accessory Nerve
FUNCTIONMotor Nerveinnervates
trapezius and Sternocleidomastoid
TEST Shoulder Shrug
against resistance Spinal Accessory Nerve (93)
XII – Hypoglossal Nerve
FUNCTIONMotor Nerve
(primarily motor)Carries motor
fibers to the tongue
TESTStick out tongue
and look for tremors Hypoglossal Nerve (94)
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