Cranial Nerves - Extended Review

Question 1

CN I

Answer 1

OLFACTORY NERVE (I)
[SENSORY - SMELL]
- found on the CRIBRIFORM PLATE OF ETHMOID
- ORIGIN:
olfactory epithelium
- DESTINATION:
olfactory bulbs
- PATHO:
ANOSMIA - loss of smell; from fracture of ethmoid bone/lesions of olfactory fibers
- CLINICAL TEST:
sniff aromatic substances

Question 2

CN II

Answer 2

OPTIC NERVE
[SENSORY - VISION]
- found on the OPTIC CANAL of SPHENOID BONE
- ORIGIN:
RETINA OF EYE
- DESTINATION:
DIENCEPHALON/OPTIC CHIASMA
- PATHO:
ANOPSIA - visual defects due to blindness in eye due to nerve
- CLINICAL TEST:
finger & eye chart

Question 3

CN III

Answer 3

OCULOMOTOR NERVE
[MOTOR - EYE MOVEMENT/PUPIL REFLEX]
- found on the SOF of SPHENOID
- ORIGIN:
midbrain
- DESTINATION:
LEVATOR PALPEBRAL SUPERIORIS
EXTRAOCULAR MUSCLES (sup, inf, med,)
- PATHO:
DIPLOPIA - double vision
EXTERNAL STRABISMUS - eye moves outward (lazy eye)
- CLINICAL TEST:
penlight & object test

Question 4

CN IV

Answer 4

TROCHLEAR NERVE
[MOTOR - EYE MOVEMENT]
- found on the SOF of SPHENOID
*smallest CN
- ORIGIN:
MIDBRAIN
- DESTINATION:
SUPERIOR OBLIQUE MUSC.
- PATHO:
DOUBLE VISION
XXX - EYE ROTATION INFEROLATERALLY
- CLINICAL TEST:
same as CN III

Question 5

CN V

Answer 5

TRIGEMINAL NERVE
[BOTH - FEEL/MASTICATION]
- found on the SOF of sphenoid
*largest CN
- ORIGIN: *has 3 branches
OPTHALMIC: eyes, nasal cavity, forehead, sup. eyelid
MAXILLARY: inf. eyelid, UPPER oral cavity
MANDIBULAR: LOWER oral cavity
- DESTINATION:
mandibular motor fibers, mastication muscles, deep ear muscle
- PATHO:
TRIGEMINAL NEURALGIA - a painful twitch in jaw area
- CLINICAL TEST:
corneal reflex test, safety pin test, open mouth test

Question 6

CN VI

Answer 6

ABDUCENS NERVE
[MOTOR - LATERAL RECTUS (EYE MUSC.)]
- found on SOF of sphenoid
- ORIGIN:
PONS (ventral)
- DESTINATION:
LATERAL RECTUS/EXTRAOCULAR MUSC.
- PATHO:
INTERNAL STRABISMUS - eye moves inward
- CLINICAL TEST:
same with CN III

Question 7

CN VII

Answer 7

FACIAL NERVE
[BOTH - FACIAL EXP., TEARS, TASTE, NASAL/SALIVARY GLANDS]
- found on TEMPORAL via IAM
- ORIGIN:
ANTERIOR 2/3 of the TONGUE
- DESTINATION:
LACRIMAL/NASAL/SUBLING/SUBMAND glands + FACIAL EXP MUSCLES
- PATHO:
BELL’S PALSY - paralysis of facial muscles/partial loss of taste
- CLINICAL TEST:
taste test & face symmetry test

Question 8

CN VIII

Answer 8

VESTIBULOCOCHLEAR NERVE
[BOTH - HEARING & BALANCE]
- found on TEMPORAL via IAM
- ORIGIN:
base b/w PONS/MEDULLA/special sensory receptors of inner ear
- DESTINATION:
vestibular branch - balance
cochlear branch - hearing
- PATHO:
DEAFNESS/VERTIGO
- CLINICAL TEST:
hearing test/tuning fork test

Question 9

CN IX

Answer 9

GLOSSOPHARYNGEAL NERVE
[BOTH - TONGUE MVMT, TASTE, SWALLOW]
- from TEMPORAL - via JUGULAR FORAMEN
*BP in the carotid artery
- ORIGIN:
POST 1/3 TONGUE, PHARYNX/PALATE, CAROTID ARTERY
- DESTINATION:
PHARYNGEAL MUSC (swallow - somatic motor)
PAROTID SALIVARY GLAND (visceral motor)
- PATHO:
IMPAIRMENT of SWALLOW, TASTE, & TONGUE MVMT
- CLINICAL TEST:
gag reflex test

Question 10

CN X

Answer 10

VAGUS NERVE
[BOTH - HR, BREATHING, GI ACTIVITY]
*only CN that leaves head region “vagrant = wanders”
- from TEMPORAL - via JUGULAR FORAMEN
- ORIGIN:
(sensory) PHARYNX/DIAPHRAGM/THORACIC/ABDOMINOPELVIC CAVITIES
- DESTINATION:
(motor)
(somatic) LARYNX, THROAT
(visceral) RESP./CARDIO/THORACIC/ABDOMINOPELVIC CAVITIES
- PATHO:
HOARSENESS/LOSS OF VOICE
- CLINICAL TEST:
same as CN IX

Question 11

CN XI

Answer 11

ACCESSORY NERVE
[MOTOR - MUSCULAR MVMT.]
- from TEMPORAL - via JUGULAR FORAMEN
- ORIGIN:
SPINAL CORD C1-C5
- DESTINATION:
STERNOCLEIDOMASTOID/TRAPEZIUS MUSC.
- PATHO:
DIFFICULTY with SHRUGGING/TURNING HEAD
- CLINICAL TEST:
rotate head test

Question 12

CN XII

Answer 12

HYPOGLOSSAL NERVE
[MOTOR - TONGUE MVMT.]
- found on OCCIPITAL via HYPOGLOSSAL CANAL
- ORIGIN:
MEDULLA
- DESTINATION:
TONGUE MUSC.
- PATHO:
DIFFICULTY in SPEECH/SWALLOWING, TONGUE SYMMETRY
*can lead to TONGUE DEVIATION to one side due to LESIONS
- CLINICAL TEST:
protrusion & retraction of tongue