(7) Cranial Nerves Flashcards
mnemonic to remember cranial nerve names
On = Olfactory Occasion= Optic Our= Oculomotor Trusty = Trochlear Truck= Trigeminal Acts = Abducens Funny= Facial Very= Vestibulocochlear Good= Glossopharyngeal Vehicle= Vagus Any= Accessory How= Hypoglossal
mnemonic to remember sensory/motor/both of cranial nerves
Some= olfactory Say= optic Money= oculomotor Matters= trochlear But= trigeminal My= abducens Brother= facial Says= vestibulocochlear Big= glossopharyngeal Brains= vagus Matter= accessory Most= hypoglossal
3 different types of nerves
sensory (afferent) vs motor (efferent)
somatic vs visceral
general sensory vs special sensory
general sensory vs special sensory example
general= pain, temperature, touch, proprioception
special= vision, hearing, smell (NOT TASTE)
6 nerve types
somatic sensory (Ss)-- sensations from face special sensory (Sp) -- smell, vision, hearing somatic motor (Sm)-- extraocular muscles (innervate skeletal muscle)
Visceral sensory (Vi)-- gut distension, taste visceral motor (A)-- salivary gland pharyngeal (P) -- facial muscle
most skeletal muscle of the body is derived from…
myotomes
innervation of myotomes is
somatic motor
some skeletal muscle in the head and neck are derived from…
branchial (gill) arches
innervation is pharyngeal motor (P)
- give rise to muscle of facial expression, chewing, jaw
what are ganglia?
similar structure and function
outside CNS (in PNS)
2 neuron chain of general visceral efferents (autonomics)
- preganglionic neuron projects to ganglion; synapses (acetycholine) onto post ganglionic neuron
- post ganglionic neuron projects to target
general visceral efferents arise entirely from…
spinal cord
general visceral efferents sympathetics emerge from
intermediate horn spinal cord (T2-L3) and travel through sympathetic chain
general visceral efferents sympathetics synapse..
either within chain or abdominal or pelvic ganglia
preganglionic and postganglionic length of general visceral efferents sympathetics
preganglionic= short
post-ganglionic= long
post ganglionic neurotransmitter
general visceral efferents sympathetics
noradrenaline
is there a sympathetic component of cranial nerves?
NO sympathetic component
general visceral efferents parasympathetics emerge from
- principle supply from cranial nerves
- part of some cranial nerves (and sacral spinal nerves)
general visceral efferents parasympathetics length of pre/post ganglionic
pre-ganglionic= long
post-ganglionic= short
post ganglionic neurotransmitter
general visceral efferents parasympathetics
acetycholine
preganglionic portiosn of general visceral efferents parasympathetics found where?
at specific nucleus in brainstem, or found in grey matter of lowest levels of the spinal cord (S2-S4)
what is CN I
Olfactory nerve
is CN I sensory/motor/both
sensory only
what type of sensory is CNI
special sensory (Sp)
- olfaction and smell
multiple elements of CNI passes from…
olfactory epithelium through skull to reach olfactory bulb where it synapses
what is CNII
Optic nerve
is CN II sensory/motor/both
sensory only
what type of sensory is CNII
Special sensory (Sp)
- vision from retina
CNII fibers cross where? terminate?
some fibers cross at optic chiasma
- terminate in thalamus (LGN), midbrain (superior colliculus), and hypothalamus
what is CNIII
oculomotor
is CNIII sensory/motor/both
motor only
what type of motor is CNIII
somatic motor (Sm)
Visceral Motor (A)
somatic motor of CNIII
- most extraocular eye muscles (medial, superior, inferior recti; inferior oblique; levator palpebrae superioris)
visceral motor of CNIII
pupil diameter
- constriction, parasympathetic
CNIII emerges from…
anterior, rostral midbrain
damage to CNIII results in
eye movement problems
6 muscles the produce eye movement
- superior rectus
- lateral rectus
- medial rectus
- inferior rectus
- superior oblique
- inferior oblique
6 different eye movements
adduction abduction elevation depression extorsion intorsion
what is adduction eye movement & what muscle
pupil toward midline/nose
- medial rectus
what is abduction eye movement & what muscle
pupil away from nose (temporally)
- lateral rectus
what is elevation eye movement & what muscle
move pupil up within orbit
- superior rectus + inferior oblique
what is depression eye movement & what muscle
move pupil down within orbit
- inferior rectus + superior oblique
what is extorsion eye movement
pupil rotate away from midline
what is intorsion eye movement
pupil rotate toward midline
levator palpebrae superioris contributes to
elevation of the upper eyelid
weakness of levator palpebrae results in (what is it called)
weakness of muscle or loss of innervation leads to droopy eye lid called ptosis
oculomotor nerve carries… (pre/post ganglionic)
preganglionc parasympathetics to the ciliary ganglion
post-ganglionic carried by the short ciliary nerve to the eye
what is CN IV
Trochlear
is CN IV sensory/motor/both
Motor only
what type of motor CN IV
somatic motor (Sm)
- extraocular eye muscles (nerve supply for superior oblique)
movement of eyeball
CN IV emerges from
posterior caudal midbrain/rostral pons
what makes CN IV special?
only nerve that emerges from posterior of brainstem
damage to CN IV results in?
when ask for depression (move down in orbit), eye deviates from midline
what is CN V
trigeminal nerve
is CN V sensory/motor/both
BOTH
what motor and sensory is CN V?
pharyngeal (P)
somatic sensory (Ss)
pharyngeal CNV (2)
(motor)
- muscles of mastication (chewing)
- inner ear muscle (tensor tympani)
somatic sensory of CN V (2)
- sensation (pain, temperature, touch, conscious proprioception) from face, scalp, cornea, nasal and oral cavity, anterior 2/3 tongue, dura (surrounding brain)
- unconscious proprioception (muscles of mastication)
where does CN V emerge from?
lateral pons, mid-pons
4 muscles of mastication
temporalis
masseter
medial pterygoids
lateral pterygoids
sensory fibers of trigeminal nerve are distributed to surface of face in what 3 divisions?
ophthalmic division
maxillary division (cheek bones)
mandibular division (lower jaw, teeth)
what is tensor tympani
muscle that attaches to tympanic membrane directly
tympanic membrane (where the ear canal terminates– the eardrum)
what is the function of tensor tympani?
dampen nose of chewing
- when tensed, muscle pulls the malleus medially, tensing tympanic membrane and damping vibration in the ear ossicles
- reducing perceive amplitude of sounds
what is CN VI?
abducens nerve
is CN VI sensory/motor/both
motor only
what type of motor is CN VI?
somatic motor (Sm)
- extraocular eye muscles (lateral rectus muscle)
damage to CN VI results in??
loss of function/weakness in lateral rectus, difficult move eye laterally
CN VI emerges from
caudal pons, medial
what is CN VII?
facial nerve
is CN VII sensory/motor/both
BOTH
what type of sensory and motor is CN VII
motor: pharyngeal, visceral motor
sensory: visceral sensory, somatic sensory
pharyngeal CN VII
muscles of facial expression
inner ear muscle (stapedius)
visceral motor CN VII
salivary glands (submandibular sublingual) via submandibular ganglia
lacrimal glands (tears) via pterygopalatine ganglia
(parasympathetic) – increases saliva and tear production
visceral sensory CN VII
anterior 2/3 tongue (Taste)
somatic sensory CN VII
skin of outer ear
CN VII emerges from
caudal pons, lateral
2 functions of muscles of facial expression?
- make you smile, frown, close eyes tightly
- many muscles innervated by facial nerve
function of the stapedius
dampens the vibrations of the stapes by pulling on the neck of that bone
- help control amplitude of sound waves
- dampens ability of stapes vibration and protects inner ear from high noise levels (own voice volume)
what is CN VIII
vestibulocochlear nerve
is CN VIII sensory/motor/both
sensory only
what type of sensory is CN VIII
special sensory (Sp)
balance and hearing
CN VIII emerges from?
caudal pons, lateral
what part of ear detects gravity
semicircular canals (part of vestibular apparatus), info is collected by vestibular nerve
- detects gravity, direction of head in space
what is CN IX
glossopharyngeal nerve
is CN IX sensory/motor/both
both
motor and sensory components of CN IX
motor: pharyngeal, visceral motor
sensory: visceral sensory, somatic sensory
pharyngeal component of CN IX
- stylopharyngeus (swallowing)
visceral motor component of CN IX
parotid gland (salivation) - parasympathetic
visceral sensory component of CN IX (3)
- taste fibers posterior 1/3 of tongue
- pharynx sensation (gag reflex) – afferent limb
- carotid body/sinus
somatic sensory component of CN IX (3)
- general sensation of posterior 1/3 of tongue
- ear: inner tympanic membrane
- outer ear skin
(pain, temperature)
visceral motor of CN IX pre/post-ganglionics
pre= synapse to otic ganglia
post= travel to parotid gland (salivary gland)
- stimulates saliva
visceral sensory of CN IX carotid body/sinus
body= chemoreceptors monitoring blood O2, CO2, and pH
Carotid sinus: baroreceptors monitoring blood pressure
- higher control of cardiac function
- sensory info carried by glossopharyngeal nerve
what is CN X?
vagus nerve
is CN X sensory/motor/both?
both
motor and sensory components of CN X
motor: pharyngeal, visceral motor
sensory: somatic sensory, visceral sensory
CN X pharyngeal component
muscles in pharynx, larynx, and upper esophagus
- speech and swallowing, gag reflex (Efferent limb)
CN X visceral motor component
- parasympathetic control of thoracic (lungs/heart) and abdominal viscera (stomach, intestine etc)
- principle parasympathetic control**
somatic sensory of CN X
- general sensation: external ear, innervate external tympanic membrane
visceral sensory of CN X (2)
- sensation from viscera; larynx, esophagus, gut
- aortic bodies (chemoreceptors, baroreceptors)
CN X emerges from
mid medulla, laterally
vagus nerve delivers pre ganglionic parasympathetic to
ganglia on target organs
- go to structures in thorax and abdomen
post-ganglionic vagus nerve located
within the target tissue, within walls/structure of visceral structures
what is CN XI
accessory nerve
is CN XI sensory/motor/both
motor only
motor component of CN XI
pharyngeal
- sternocleidomastoid and trapezius muscles
- movement of head and shoulders
CN XI is formed by
rootlets from cervical spinal cord
what is CN XII
hypoglossal nerve
is CN XII sensory/motor/both
motor only
motor component of hypoglossal nerve
somatic motor
- muscles of tongue
- movement of tongue
CN XII emerges from
medulla, laterally (more anterior)
which 3 nerves are purely special sensory
CNI olfactory
CNII optic
CN IX vestibulocochlear
which nerve is both somatic and visceral motor
CN III oculomotor
what 5 nerves are purely motor
CN II optic - extraocular eye muscles CN III oculomotor - extraocular eye muscles CN VI abducens- extraocular eye muscles CN XI accessory CN XII hypoglossal
what 4 nerves are both motor and sensory
CN V trigeminal
CN VII facial
CN IX glossopharyngeal
CN X vagus
cranial nerve nuclei are organized into ….
functional columns
at what levels of the spinal cord is somatic present??
every level
at what levels of the spinal cord is visceral present?
thoracic and sacral
what type of nerve is most medial?
somatic motor
motor=medial
what type of nerve is most lateral?
special sensory
sensory=lateral
cranial nerve nuclei compact and restricted to a…
restricted (rostral-caudal) to a sub-region of a single level of brainstem
- typically near the level where nerve emerges/enters the brainstem
caudal medulla at pyramidal decussation what cranial nerve nucleus is present?
- associated with what nerve?
somatic sensory nucleus associated with trigeminal nerve
the trigeminal sensory nucleus extends where?
extends full length of the brainstem
trigeminal sensory nucleus 3 components
- spinal trigeminal nucleus (lower part)= medulla + pons
- main sensory nucleus (where nerve connects)= pons
- mesencephalic nucleus (upper part)= pons + midbrain
3 somatic sensory modalities of spinal trigeminal nucleus
crude touch, pain and temperature
- spinothalamic tract
2 somatic sensory modalities of
discriminative touch and conscious proprioception
- dorsal column medial lemniscus pathway
somatic sensory modality of mesencephalic nucleus
unconscious proprioception
- associated with muscles of mastication
- spinocerebellar pathways
CN V primary neuron 2 locations
in the trigeminal ganglion (of spinal trigeminal nucleus)
and the mesencephalic nucleus
output from the spinal and main nuclei do what?
cross and enter the spinothalamic tract and medial lemniscus
- travel to the thalamus (ventral posterior nucleus)
- then to somatosensory cortex
mesencephalic nucleus projections go to
trigeminal motor nucleus providing proprioceptive feedback (and reflexes) for muscles of mastication
- also projections to the cerebellum (trigeminocerebellar fibres) via the inferior cerebellar peduncle
caudal medulla (caudal to the obex) is dominated by (what 2 things)
SpVn = spinal trigeminal nucleus
SpVtr= spinal trigeminal tract
what is the hypoglossal nucleus
somatic motor (most medial)
what is the vagas nerve nucleus (autonomic)
dorsal motor nucleus of the vagus
- autonomic( parasympathetic)
solitary nucleus and tract
- carries fibres for what 3 cranial nerves?
visceral sensory
- tract carries fibers from CN VII (facial), IX (glossopharyngeal), X (vagus)
solitary nucleus projects to
ventral posterior nucleus and hypothalamus (ipsilateral)
via the central tegmental tract
visceral sensory info from solitary nucleus is carried by..
central tegmental tract to the thalamus
at the caudal pons, fibers for what cranial nerves are present?
fibers for abducens (CN VI) and facial nerves (CNVII)
at the caudal pons what 2 cranial nerve nuclei are present
- facial motor nucleus (pharyngeal)
- abducens nucleus (somatic motor)
course of projections from the facial nucleus
projections go first posterior and rostral, then hair pin turn and wraps around abducens nucleus to exit the brainstem
- turn gives rise to the facial colliculus, and is formed by internal genu
internal genu of the facial nerve are the… and form the….
they are the most posterior fibers
produce facial colliculus
what 3 trigeminal nerve nuclei are present at mid pons
- main nucleus
- mesencephalic nucleus (unconscious proprioception)
- motor nucleus (pharyngeal)- muscles of mastication
what cranial nerve nuclei is present at the rostral pons
continuation of mesencephalic nucleus of the trigeminal nerve (CN V)
what cranial nerve nuclei is present at the caudal midbrain
trochlear nucleus (trochlear nerve, CN IV)
somatic motor, medially located
what is so special about the trochlear nerve nuclei
it is the only CN with motor nucleus that decussates, and exits posterior margin
4 somatic motor nerve nuclei
oculomotor nucleus (CN III) trochlear nucleus (CN IV) abducens nucleus ( CN VI) hypoglossal nucleus (CN XII)
where is the medial longitudinal fissure located
always present at midline
connects nuclei associated with eye movements
- CN III (oculomotor)
- CN IV (optic)
- CN VI (abducens)
4 pharyngeal nerve nuclei
Trigeminal motor nucleus (CN V) - mid pons
facial motor nucleus (CN VII) - caudal pons
nucleus ambiguus (glossopharyngeal, vagus)
accessory nucleus (CN XI)
5 autonomic parasympathetic nerve nuclei
- nucleus of edinger westphal (CN III oculomotor)
- superior salivary nucleus (CN VII facial)
- inferior salivary nucleus (CN IX glossopharyngeal)
- dorsal motor nucleus of the vagus (CN V)
- nucleus ambiguus (CN X vagus)
nucleus of edinger westphall
CN III (oculomotor)
innervation of iris via ciliary ganglia
superior salivary nucleus
CN VII (facial)
innervation of lacrimal gland via pterygopalatine ganglia and submandibular gland via submandibular ganglia
inferior salivary nucleus
CN IX (glossopharyngeal)
- innervation of parotid gland via otic ganglia
exception to rule of one nucleus, one functional type
- pharyngeal/branchiomeric component
- autonomic component
visceral sensory of the solitary nucleus and tract
found in medulla, tract extending from pons
- taste sensation mediated by upper portion of solitary nucleus
- viscera = lower part of nucleus
primary visceral sensory neurons for CN VII found in…
geniculate ganglion
primary visceral sensory neurons for CN IX found in
inferior ganglion of IX
primary visceral sensory neurons for CN X found in
inferior ganglion of X
what are considered visceral sensations?
blood pressure, blood oxygen level
primary somatic sensory neurons for CN V are located in (2)
trigeminal ganglia and mesencephalic nucleus
fibers from CN VII, IX and X project to the …
spinal nucleus and the main sensory necleus via the spinal tract
- skin of the ear
CN VII primary somatic sensory neuron
geniculate ganglion
- project to spinal trigeminal nucleus
(from outer ear)
CN VII primary visceral sensory neuron
geniculate ganglion
- project to solitary nucleus, travel with tract
(taste buds anterior 2/3 tongue)
CN VII pharyngeal nucleus
facial motor nucleus (does loop)
- muscles of facial expression and stapedius
CN VII visceral motor nucleus
to salivary, nasal and palatine and lacrimal glands (via submandibular and pterygopalatine ganglia)
- superior salivary nucleus give rise to preganglionic fibers to ganglia that innervate salivary and lacrimal glands
CN IX primary somatic sensory neuron
superior ganglia of IX
- project ot spinal trigeminal nucleus
CN IX primary visceral sensory neuron
inferior ganglion of IX
2 visceral sensory
- taste buds posterior 1/3 tongue
- carotid body, and sinus, mucosa, pharynx, posterior tongue, middle ear (travel to solitary nucleus)
CN IX brachial motor (pharyngeal) nucleus
nucleus ambiguus
CN IX visceral motor projects to
parotid glands via otic ganglion
CN X primary somatic sensory nuclei
superior ganglion of X
outer ear
- project to spinal trigeminal nucleus
CN X primary visceral sensory nuclei
inferior ganglion of X
2 visceral sensory
- from epiglottal taste buds
- from larynx, pharynx, thorax, abdomen
CN X brachial motor projects to
larynx and pharynx
CN X visceral motor 2 components
thorax and abdomen
