Cranial Nerves Flashcards
cranial nerves
nerves that exit from the brain to transmit information to/from the brain
are cranial nerves part of the CNS or PNS
PNS
exceptions: CN I and II
where do most cranial nerves exit
ventral brainstem
exception: CN I and II (enter brain)
skull foramina
openings in the skull that allow passage of cranial nerves and vessels
extraocular muscles
muscles attached to the eye that are involved in eye movement
- dorsal rectus
- ventral rectus
- lateral rectus
- medial rectus
- dorsal oblique
- ventral oblique
- retractor bulbi
dorsal rectus
moves eye upward
ventral rectus
moves eye downward
lateral rectus
moves eye to the outside (away from nose)
medial rectus
moves eye to the inside (toward nose)
retractor bulbi
pulls eye back into socket
strabismus
misalignment of the eye
CN I
olfactory nerve
(NOT an actual nerve - bundle of sensory nerve fibers)
CN I function
afferent: special sense of smell
has olfactory receptors in nasal epithelium
CN I exit
olfactory bulb –> cribriform plate –> nasal epithelium
CN II
optic nerve
(NOT an actual nerve - bundle of sensory nerve fibers)
CN II function
afferent: supplies visual information
has rods/cones (receptors) in the retina
CN II entry
optic canal
enters cranial vault (NOT exit)
CN III
oculomotor nerve
CN III function
efferent: motor to 4 extraocular muscles (DR, VR, MR, VO) and lifts eyelid
parasympathetic: pupil constriction
CN III exit
orbital fissure
CN IV
trochlear nerve
CN IV function
efferent: motor to 1 extraocular muscle (contralateral DO)
CN IV exit
orbital fissure
exits brainstem dorsally
CN V
trigeminal nerve
CN V function
afferent: sensory to face
efferent: motor to muscles of mastication
branches of CN V
- ophthalmic (afferent)
- maxillary (afferent)
- mandibular (efferent)
CN V exits
ophthalmic: orbital fissure
maxillary: round/rostral alar foramen
mandibular: oval foramen
CN VI
abducens nerve
CN VI function
efferent: motor to 2 extraocular muscles (LR, RB)
CN VI exit
orbital fissure
CN VII
facial nerve
CN VII function
afferent: special sense of taste, sensory to inner pinna
efferent: motor to muscles of facial expression
parasympathetic: salivary and lacrimal glands
CN VII exit
stylomastoid foramen
CN VIII
vestibulocochlear nerve
CN VIII function
afferent: sensory for hearing and balance
CN VIII exit
internal acoustic meatus
exits cranial cavity NOT skull
CN IX
glossopharyngeal nerve
CN IX function
afferent: sensory and taste to upper pharynx and caudal 1/3 of tongue
efferent: motor to muscles of the pharynx
parasympathetic: visceral sensory information (BP, pCO2, blood pH), parotid and zygomatic salivary glands
CN IX exit
jugular/tympano-occipital foramen
CN X
vagus nerve
CN X function
afferent: sensory to pharynx, back of ear, external meatus, taste to epiglottis
efferent: motor to muscles of the pharynx and most of larynx
parasympathetic: visceral sensory functions (decrease HR, increase bronchoconstriction, increase GI secretion/motility)
CN X exit
jugular/tympano-occipital foramen
CN XI
accessory nerve
CN XI function
efferent: motor to muscles of larynx and esophagus, neck, and shoulders
CN XI exit
jugular/tympano-occipital foramen
cranial and spinal roots split but both exit at same opening
CN XII
hypoglossal nerve
CN XII function
efferent: motor to intrinsic (some extrinsic) muscles of the tongue
CN XII exit
hypoglossal foramen
afferent only cranial nerves
CN I - olfactory
CN II - optic
CN VIII - vestibulocochlear
efferent only cranial nerves
CN III - oculomotor
CN IV - trochlear
CN VI - abducens
CN XI - accessory
CN XII - hypoglossal
mixed cranial nerves
CN V - trigeminal
CN VII - facial
CN IX - glossopharyngeal
CN X - vagus
cranial nerves with parasympathetic fibers
CN III - oculomotor
CN VII - facial
CN IX - glossopharyngeal
CN X - vagus
CN III (oculomotor) deficits
mydriasis
ventro-lateral strabismus
drooping eyelid
CN IV (trochlear) deficits
difficult to assess rotation
best seen in animals with vertical/horizontal pupils
CN VI (abducens) deficits
medial strabismus
CN VII (facial) deficits
droopy face
CN XII (hypoglossal) deficits
paralysis/paresis or atrophy of the tongue muscles
CN V: ophthalmic branch function
sensory to upper part of face, dorsal nasal cavity, majority of eye and associated structures
CN V: maxillary branch function
sensory to lower eyelid, lateral skin around eyes, nasal mucosa, upper teeth/lip/palate, and nose
CN V: mandibular branch
sensory to rostral 2/3 of tongue, oral cavity, and lower face/teeth
motor to muscles of mastication, opens auditory tube
CN V (trigeminal) deficits
ophthalmic: corneal ulcers due to loss of protective mechanism
mandibular: open jaw, head muscle atrophy
salivation nerve pathway
afferent: CN VII (taste)
efferent: CN VII via chorda tympani nerve (parasympathetic)
