ANATOMY - cranial nerves Flashcards
what is the modality of CN I (olfactory nerve)
special sensory - smell
what is the extracranial location of CN I (olfactory nerve)
lies within the olfactory mucosa in nasal cavity
what cranial foramina does CN I (olfactory nerve) pass through
cribriform plate of the ethmoid bone in the anterior cranial fossa
what is the intracranial course of CN I (olfactory nerve)
olfactory nerve synapses in the olfactory bulbs then pass through olfactory tract to cortical areas
where is the primary olfactory cortex
temporal lobe
how would you test CN I (olfactory nerve)
ask patient to smell a smell and cover other nostril
CN I is the ____ cranial nerve
shortest
CN I (olfactory nerve) is the only sensory modality that doesnt synapse in the _____ prior to reaching cortex
thalamus
what is the modality of CN II (optic nerve)
special sensory - vision
what is the extracranial course of the CN II (optic nerve)
neurones of the retina travel posteriorly via optic nerve from posterior hemisphere of eye through the orbit
what cranial foramina does CN II (optic nerve) pass through
optic canal in the middle cranial fossa
what is the intracranial course of CN II (optic nerve)
travels around the pituitary stalk to optic chiasm to form optic tract
what is the CN II (optic nerve) connection with the CNS
diencephalon
how can CN II (optic nerve) be tested
Acuity - snellen chart colour - ishihara plates fields - 4 quadrants reflexes - pupillary light reflexes fundoscopy
what is the modality of CN III (oculomotor)
somatic motor
what does CN III (oculomotor) supply motor control to
levator palpebra superioris (LPS)
SR, MR, IR, IO (AO3)
CN III (oculomotor) also has autonomic features. What does it provide autonomic supply to and what does this cause
sphinter pupillae and ciliary muscle - pupil constriction
what is the intracranial course of CN III (oculomotor)
travels towards the orbit in the lateral wall of the cavernous sinus
what cranial foramina does CN III (oculomotor) pass through
SOF
what is the extracranial course of CN III (oculomotor)
passes through SOF into orbit and supplies all extraocular muscles except 2
where is the parasympathetic synapse of CN III (oculomotor)
ciliary ganglion
what is CN III (oculomotor) connection with the CNS
superior colliculus of the midbrain (mesencephalon)
how can the parasympathetics of CN III (oculomotor) be tested
pupillary light reflex
how can the motor supply of CN III (oculomotor) be tested
H test
where are preganglionic parasympathetic neurons of CN III (oculomotor) found
Edinger-Westphal nucleus
where are somatic motor neurons of CN III (oculomotor) found
oculomotor nucleus
what is the modality of CN IV (trochlear)
somatic motor
what does the motor supply of CN IV (trochlear) go to
Superior oblique
what is the intracranial course of CN IV (trochlear)
travels towards the orbit in the lateral wall of the cavernous sinus
what cranial foramina does CN IV (trochlear) pass through
SOF
what is the extracranial course of CN IV (trochlear)
passes through SOF into orbit and supplies SO
what is CN IV (trochlear) connection with the CNS
inferior colliculus - lower midbrain (mesencephalon)
how can the motor supply of CN IV (trochlear) be tested
H test
CN IV (trochlear) is the only cranial nerve to exit _____
posteriorly
does CN IV (trochlear) cross the midline
yes
what are the 3 divisions of the trigeminal nerve (CN V)
CN V1 - opthalmic division
CN V2 - maxillary division
CN V3 - mandibular division
what are the modalities of the 3 branches of trigeminal nerve (CN V)
CN V1 - sensory
CN V2 - sensory
CN V3 - sensory and motor
what is trigeminal nerve (CN V) connection with the CNS
Pons
what is the intracranial course of trigeminal nerve (CN V)
inferior to edge of tentorium cerebelli between the posterior and middle cranial fossa
what cranial foramina do the branches of trigeminal nerve (CN V) go through
V1 - SOF
V2 - foramen rotundum
V3 - foramen ovale
what is the extracranial course of the sensory axons of trigeminal nerve (CN V)
course from the superficial and deep structures of the face posteriorly towards respective cranial foramena
what is the extracranial course of the motor axons of mandibular division of trigeminal nerve CNV3
course from the foramen ovale towards the skeletal muscles they supply
what is the superficial sensory supply of CN V1 (5)
forehead upper eyelid cornea all conjunctiva skin of root/tip/bridge of nose
what is the deep sensory supply of CNv1 (4)
bones and soft tissue of the orbit (except orbital floor and lower eyelid)
upper anterior nasal cavity
paranasal sinuses (Except maxillary sinus)
anterior and posterior cranial fossa
what is the superficial sensory supply of CN V2 (4)
skin of lower eyelid
skin over maxilla
skin of ala of nose
skin/mucosa of upper lip
what is the deep sensory supply of CN v2 (5)
lower posterior nasal cavity maxilla maxillary sinus floor of nasal cavity/palate maxillary teeth and assoc. soft tissues (gingiva and mucosa)
what is the superficial sensory supply of CN V3
skin over mandible and TMJ
what is the deep sensory supply of CN V3 (6)
middle cranial fossa mandible anterior 2/3 of tongue floor of mouth buccal mucosa mandibular teeth and assoc. soft tissues
what supplies the angle of the mandible
C2 C3 (greater auricular nerve)
what does CN V3 provide motor supply to (5)
muscles of mastication tensor veli palatini tensor tympani mylohyoid anterior belly of digastric
what are the 3 jaw closing muscles
masseter
temporalis
medial pterygoid
what is the jaw opening muscle
lateral pterygoid
what nucleus receives sensory information from trigeminal nerve (CN V) with proprioceptive information from chewing muscles
mesencephalic nucleus
what is the main nucleus involved in trigeminal nerve (CN V)
pontine trigeminal nucleus
what does the pontine trigeminal nucleus receive information about
discriminative touch, vibration
what trigeminal nuclei receives information regarding pain and temperature
spinal nucleus
the mesencephalic nucleus is the only site in the CNS where …
cell bodies of primary afferent neurons live inside the CNS
sensory nuclei of trigeminal nerve (CN V) forms a long column of neurones that stretch down from _____ to ____
midbrain
upper 2 segments of the cervical spinal cord
what forms the 1st part of the afferent branch of the corneal reflex
long ciliary nerves
what forms the 2nd part of the afferent branch of the corneal reflex
CN V1
what forms the efferent limb of the corneal / blink reflex
CN VII
how can the sensory innervation of trigeminal nerve (CN V) be tested
ask patient to close eyes and gently brush the skin in each area with a fine tip of cotton wool
ask patient to say when they can feel it and compare both sides
how could the motor innervation of trigeminal nerve (CN V) be tested
palpate the strength of contraction of the masseter and temporalis by asking patient to clench teeth
ask patient to open jaw against resistance
what is the modality of CN VI (abducent)
somatic motor - eye movement
what does CN VI (abducent) supply
Lateral rectus
what is the way to remember what nerves supply what extraocular eye muscles
LR6 SO4 AO3
what is CN VI (abducent) connection with the CNS
pontomedullary junction (caudal pons)
what is the intracranial course of CN VI (abducent)
travels towards the orbit within the cavernous sinus
what cranial foramina does CN VI (abducent) pass through
SOF
what is the extracranial course of CN VI (abducent)
passes through SOF into orbit to supply LR
how can the motor function of CN VI (abducent) be tested
H test
what is the modality of CN VII (facial nerve)
special sensory (taste)
motor
parasympathetic
what is the connection of CN VII (facial nerve) with the CNS
pontomedullary junction (caudal pons)
what is the intracranial course of CN VII (facial nerve)
directly into IAM in posterior cranial fossa
what cranial foramen does CN VII (facial nerve) pass through
IAM (in) stylomastoid foramen (out)
where is the IAM located
petrous temporal bone
the facial nerve courses through the petrous part of the temporal bone in the ____ ear via the ____ ___
middle
facial canal
the facial nerve splits into 4 main branches what are they
chorda tympani
nerve to stapedius
greater petrosal nerve
terminal motor branches
what does the chorda tympani supply
special sensory (taste) to anterior 2/3 of the tongue parasympathetic supply to submandibular and sublingual glands (secretomotor)
what does the greater petrosal nerve supply
parasympathetic supply to mucous glands and lacrimal glands
what does the nerve to the stapedius supply
motor supply to stapedius muscle
CN VII (facial nerve) increases/reduces stapedius muscle movement
reduces
to protect internal ear from excessive noise
parasympathetics to the lacrimal and mucous glands of the midface come from CN VII (facial nerve) that supplies parasympathetics to the ______ ganglion
pterygopalatine ganglion
the somatic motor axons of CN VII (facial nerve) supply what
muscles of facial expression
the motor branch of CN VII (facial nerve) passes out of the ________ ____, passes ____ to the ear and goes through the _____ ____
stylomastoid foramen, anterior to the ear
goes through the parotid gland
what are the 5 branches of the facial nerve
Temporal branch Zygomatic branch Buccal branch Marginal mandibular branch Cervical branch
give 4 muscles of facial expression
frontalis
orbicularis oculi
elevators of lips
orbicularis oris
where do the muscles of facial expression originate and insert
on bone
insert into superficial fascia
how can the motor function of the facial nerve be tested
ask patient to raise eyebrows, close eyes tightly, smile, puff out cheeks, hold air
what nerve does chorda tympani join with to supply the sublingual and submandibular glands
lingual nerve (CN V3)
the facial nerve has _ components and _ nuclei
3
2
what is the modality of CN VIII (vestibulocochlear)
special sensory - hearing and balance
what is the extracranial course of CN VIII (vestibulocochlear)
axons from cochlear and vestibular apparatus
what cranial foramina does CN VIII (vestibulocochlear) pass through
IAM in posterior cranial fossa
where is CN VIII (vestibulocochlear) connection with the CNS
pontomedullary junction
how can CN VIII (vestibulocochlear) be tested
Renne and Weber tests
what is the modality of CN IX (glossopharyngeal)
special sensory - taste sensory motor visceral afferent parasympathetic
what is CN IX (glossopharyngeal) connection with the CNS
upper medulla
CN IX (glossopharyngeal) has _ components
4
what are the 4 nuclei of CN IX (glossopharyngeal)
solitary nucleus
spinal trigeminal nucleus
inferior solitary nucleus
nucleus ambiguus
what is the intracranial course of CN IX (glossopharyngeal)
directly towards jugular foramen in posterior cranial fossa
what cranial foramina does CN IX (glossopharyngeal) pass through
jugular foramen
what is the extracranial course of CN IX (glossopharyngeal)
descends towards pharynx and mouth
what does CN IX (glossopharyngeal) provide general sensory innervation to
posterior 1/3 tongue
mucosa of most of nasopharynx and oropharynx
mucosa of some of laryngopharynx (overlap with CN X)
palatine tonsil
eustachian tube
middle ear cavity
what does CN IX (glossopharyngeal) provide special sensory (taste) to
vallate papillae (with taste buds) or posterior 1/3 tongue
what does CN IX (glossopharyngeal) provide visceral afferent to
carotid sinus baroreceptors and carotid body chemoreceptors
what does CN IX (glossopharyngeal) provide somatic motor to
stylopharyngeus
what does CN IX (glossopharyngeal) provide parasympathetic supply to
parotid gland (secretomotor) otic ganglion
general sensory axons of CN IX (glossopharyngeal) form the afferent limb of what reflex
gag
how can you test to see if CN IX (glossopharyngeal) is working
gag reflex
pain from the pharynx can refer where and why
ear
both sensory supply from CN IX (glossopharyngeal)
carotid sinus massage is used in the management of what
specific tachycardias
what splits tongue into posterior 1/3 and anterior 2/3
midline location of foramen caecum - site of origin of thyroid
what is the modality of CN X (vagus nerve)
sensory + special sensory
motor
visceral afferent
parasympathetic
where is CN X (vagus nerve) connected to the CNS
upper medulla, immediately inferior to CN IX
CN X (vagus nerve) has _ components
4
what are the 4 nuclei of CN X (vagus nerve)
dorsal nucleus - motor and parasympathetic
solitary nucleus
spinal trigeminal nucleus
nucleus ambiguus
what is the intracranial course of CN X (vagus nerve)
directly towards jugular foramen in posterior cranial fossa
what cranial foramen does CN X (vagus nerve) pass through
jugular foramen
in the neck CN X (vagus nerve) runs within what
carotid sheath
in the carotid sheath CN X (vagus nerve) travels posterior to and between what
common carotid artery
internal jugular vein
CN X (vagus nerve) gives off the recurrent laryngeal nerves. what do these hook under
left - under arch of aorta
right - under right subclavian artery
in the chest the right vagus nerve travels on the lateral aspect of ____
trachea
in the chest the left vagus nerve travels on the lateral aspect of the ____
aortic arch
both vagus nerves pass ____ to the lung root
posterior
both vagus nerves pass through diaphragm on the surface of the ____ at level ____
oesophagus
T10
what ganglia do branches of the vagus nerve pass onto in the abdomen
coeliac and superior mesenteric ganglia
both CN X pass onto surface of ___ in the abdomen
stomach
CN X provides parasympathetic function to what
smooth muscle of the trachea, bronchi and gastro-intestinal tract up until the splenic flexure and regulates heart rhythm
where do the very last parasympathetic axons of the vagus nerve pass to
splenic flexure
CN X provides motor innervation to what
majority of the muscles of the pharynx, soft palate and larynx (not the stylopharyngeus)
also palatoglossus
CN X provides special sensory (taste) to what
epiglottis
what branches of CN X innervate the muscles of the pharynx
pharyngeal branches
what branches of CN X innervate the muscles of the larynx
recurrent laryngeal nerves
except cricothyroid - external laryngeal nerve
vagus nerve provides sensory innervation to what
pharynx larynx trachea oesophagus and thoracic and abdominal viscera
how could you test CN X motor function: muscles of the palate
ask patient to say ahh
uvula should lift straight up in the midline
if there is unilateral pathology, uvula will point to the working side
how could you test CN X motor function: pharyngeal muscles
ask patient to swallow small amount of water
how could you test CN X motor function: laryngeal muscles
ask patient to speak
asking the patient to say ahh also tests what
CN V3
what is the modality of CN XI (spinal accessory nerve)
motor
what does CN XI (spinal accessory nerve) provide motor supply to
sternocleidomastoid and trapezius
what is CN XI (spinal accessory nerve) connection with the CNS
cervical spinal cord
what is the intracranial course of CN XI (spinal accessory nerve)
ascends through foramen magnum then travels towards jugular foramen in posterior cranial fossa
what cranial foramina does CN XI (spinal accessory nerve) pass through
jugular foramen in posterior cranial fossa
what is the extracranial course of CN XI (spinal accessory nerve)
axons supply SCM on deep surface then continue across the posterior triangle to supply trapezius and SCM
how can you test CN XI (spinal accessory nerve)
ask patient to shrug shoulders, turn head, flex neck and turn towards opposite side
what modality is CN XII (hypoglossal nerve)
motor
what does CN XII (hypoglossal nerve) supply motor function to
muscles of the tongue (except 1)
what is the exception to CN XII (hypoglossal nerve) supplying muscles of the tongue
palatoglossus is supplied by CN X
what muscles of the tongue does CN XII (hypoglossal nerve) supply
genioglossus
hyoglossus
styloglossus
what is the CN XII (hypoglossal nerve) connection to the CNS
via many rootlets lateral to the pyramids of the medulla
what is the intracranial course of CN XII (hypoglossal nerve)
passes anteriorly to hypoglossal canal
what is the extracranial course of CN XII (hypoglossal nerve)
descends lateral to carotid sheath and at level of hyoid turns anteriorly towards lateral aspect of tongue
how can CN XII (hypoglossal nerve) be tested
ask patient to stick out tongue - tongue will point to side of unilateral lesion
what is the only cranial nerve to exit laterally
VIII
the soma of sensory nerve cells of cranial nerves will be found where
ganglia outside the CNS - analogous to the DRGs for the spinal nerves (except mesencephalic - CN V)
what CNs emerge close to midline
III
IV
VI
XII
true/false
each cranial nerve has their own nuclei which is only used by that nerve
false
many nuclei in the brainstem are shared by more than one cranial nerve
what tract gives motor input to cranial nerves
corticobulbar
corticobulbar input is bilateral except for ….
facial nerve which is only bilateral to area of forehead and around eyes - below this is only a crossed fibre (contralateral)
CN palsy:
down and out eye
dilated pupil
ptosis
CN III
CN IV palsy
vertical diplopia and head tilt away from the affected side
what makes the vertical diplopia of CN IV palsy worse
walking
reading
CN palsy:
diplopia
affected eye resting in adduction and inability to abduct the eye.
CN VI
affected eye resting in adduction (due to unopposed activity of the medial rectus)
what is the most common cause of accessory nerve palsy
iatrogenic e.g. lymph node removal
inputs to parasympathetic cranial nerves mainly come from where
hypothalamus
