Intro to Cranial Nerves Flashcards
what cranial nerve nuclei DO NOT originate in the brainstem?
CNI and CNII (outgrowth of forebrain)
function of CNI
special sense (olfaction - smell)
where do CN I fibers pass?
cribiform plate and synapse in olfactory bulb
where do secondary neurons for CNI travel?
secondary neurons travel from olfactory bulb down olfactory tract to the forebrain
function of CNII
special sense (sight)
where do fibers from CN II go?
leave retina and enter middle cranial fossa via optic canal
what is unique about CN II?
fibers cross each other in the optic chiasm before forming optic tracts
function of CN III
somatic motor and parasympathetic
what somatic motor function does CN III provide
- superior rectus m 2. medial rectus m 3. inferior rectus m 4. inferior oblique m
what parasympathetic function does CN III carry?
innervates sphincter pupillae m, causes pupillary constriction
where does CN III exit the cranium?
superior orbital fissure
function of CN IV
motor to superior oblique m, extraocular muscle
where does CN IV exit the cranium?
superior orbital fissure
function of CN V?
somatic motor and sensory
muscles of mastication
- temporalis 2. masseter 3. medial pterygoid 4. lateral pterygoid
motor innervation of CN V?
- deep temporal nerves (off V3) – Temporalis 2. masseteric nerve (off V3) – masseter 3. nerve to medial pterygoid (off V3) – medial pterygoid and tensor veli palatini 4. nerve to lateral pterygoid (off V3) – lateral pterygoid 5. nerve to mylohyoid (off V3 - specifically inferior alveolar) – mylohyoid and anterior belly of digastric
what muscles does CN V innervate?
- temporalis 2. masseter 3. medial pterygoid 4. tensor veli palatini 5. lateral pterygoid 6. mylohyoid 7. anterior belly of digastric
sensory innervation of CNV
sensory innervation of face and anterior 2/3 of tongue (via lingual)
what contains cell bodies for sensation to the face?
trigeminal ganglion (in the medial cranial fossa, under dura)
explain the sensory innervation of V1
from scalp to upper eyelid and bridge and tip of nose
explain sensory innervation of V2
lower eyelid, side of nose to upper lip
explain the sensory innervation of V3
lower lip to around chin
branches of V3
- auriculotemporal n
- meningeal branch
- posterior deep temporal n
- anterior deep temporal n
- masseteric n
- buccal n to buccinator muscle
- lingual n
- inferior alveolar n
- n to mylohyoid
- n to lateral pterygoid
- n to medial pterygoid and tensor veli palatini
- mental n
- n to tensor tympani
- lesser petrosal n (from glossopharyngeal N)
- parotid branches
- articular and anterior auricular branches
- superficial temporal
function of CN VI
somatic motor
motor innervation of CNVI
lateral rectus muscle
how does CNVI exit cranium?
superior orbital fissure
what could result from damage to CNVI?
medial strabismus of eye - ESOTROPIA (uninhibited medial rectus activity due to inactive lateral rectus)
function of CNVII
- special sense (taste)
- somatic motor
- parasympathetic
special sense function of VII
taste to anterior 2/3 of tongue via chorda tympani
motor innervation branches of CNVII
- posterior auricular branch
- temporalis
- zygomatic
- buccal
- mandibular
- cervical
muscles innervated by CNVII
muscles of facial expression plus extra
specific muscles innervated by CNVII
- auricularis anterior – PA and temporal
- auricularis posterior – PA and temporal
- auricularis superior – PA and temporal
- buccinator – buccal
- corrugator supercili – zygomatic and temporal (hate lines)
- depressor anguli oris – mandibular and buccal
- depressor labii inferioris – mandibular and buccal
7a. depressor septi nasi – zygomatic and buccal - posterior belly of digastric
- frontal belly of occipitofrontalis – temporal
- levator anguli oris – zygomatic and buccal
- levator labii superioris – zygomatic and buccal
- levator labii superioris alaeque nasi – zygomatic and buccal (flares nostril)
- mentalis – marginal mandibular
- nasalis – zygomatic and buccal
- occipital belly of occipitofontralis m – PA
- orbicularis oculi
- orbicularis oris – zygomatic, buccal, mandibular
- platysma
- stapedius `
- stylohyoid
- zygomaticus major – zygomatic and buccal
- zygomaticus minor – zygomatic and buccal
action of auricularis anterior
elevates and draws ear forward
action of auricularis posterior – PA and temporal
retract and elevate ear
action of auricularis superior
retract and elevate ear
action of buccinator
mastication, compresses cheeks and expels air between lips (duck face)
action of corrugator supercilli
draws eyebrows downward and medially (hate lines)
action of depressor labii inferioris
depresses angle of mouth
action of depressor septi nasi
narrows nostril and draws septum down
action of depressor labii inferioris
depress lower lip and draws downward
action of frontal belly of occipitofrontalis
raises eyebrows
action of levator anguli oris
elevates angle of mouth
action of levator labii superioris alaeque nasi
dilates nostril, elevates upper lip
action of levator labii superioris
dilates nares and elevates upper lip
action of mentalis
raises and protrudes lower lip (pouty face)
action of nasalis
draw ala of nose toward nasal septum, compress nostrils, opens nostrils
acction of occipital belly of occipitofrontalis
moves scalp backward
action of orbicularis oculi
closes eyelids
action of orbicularis oris
compression, contraction, protrusion of lips (pursing, duck face)
action of platysma
tenses skin of neck
action of procerus
draws down medial aspect of eyebrows, transferse wrinkles of bridge of nose
action of risorius
retracts angle of mouth
action of zygomaticus major
draws angle of mouth backward and upward
action of zygomaticus minor
elevates upper lip
parasympathetics of CNVII
greater petrosal nerve and chorda tympani supply lacrimal, sublingual and submandibular glands
where does CNVII exit
internal acoustic meatus, and then through stylomastoid foramen
action of CNVIII
special sense – hearing and balance
where does CNVIII exit>
internal acoustic meatus, then splits into cochlear and vestibular nerves
what occurs once CNVIII enters internal acoustic meatus?
splits into cochlear nerve for hearing and vestibular nerve for equilibrium and balance
function of CNIX
- somatic motor
- general sense
- special sense – taste
- parasympathetic
motor innervation of CNIX
stylopharyngeus only
somatic innervation of CNIX
sensory to portions of pharynx, soft palate, posterior 1/3 of tongue
special sense of CNIX
taste to posterior 1/3 of tongue
explain somatic and special sensory innervation of the tongue
anterior 2/3 – taste: chorda tympani from CNVII, general sense: lingual N from V3
posterior 1/3 – taste and general sense: CN IX
parasympathetic innervation of CNIX
parasympathetic to parotid gland
where does CNIX exit the cranial fossa?
jugular foramen (with 10 and 11)
function of CNX
- somatic motor
- sensory
- parasympathetic
motor suppy of CNX
soft palate, pharynx, intrinsic laryngeal muscles via recurrent laryngeal
sensory innervation CNX
inferior pharynx and larynx
parasympathetic innervation CNX
parasympathetic to thorax and abdomen
where does CNX leave cranial fossa?
jugular foramen with IX and XI
function of CN XI
somatic motor
what muscles does XI innervate?
trapezius and sternocleidomastoid
what makes up CNXI?
rootlets from C1-C5
describe the route of CNXI
travels into the foramen magnum from the spinal cord (C1-C5) and then leaves the posterior cranial fossa via jugular foramen
what is a sign of CNXI injury?
saggy drooped shoulder from lack of trapezius
function of CNXII
somatic motor to intrinsic and extrinsic muscles of tongue
where does CNXII leave posterior cranial fossa?
hypoglossal canal
sign of CNXII damage?
apex of tongue deviates toward the damaged side
what nerves exit through the superior orbial fissure?
- oculomotor (3)
- trochlear (4)
- opthalmic (5-1)
- abducens (6)
what nerves travel through the cavernous sinus?
- oculomotor (3)
- trochlear (4)
- opthalmic (5-1)
- maxillary (5-2)
- abducens (6)
