HS2-3 Cranial Nerves Flashcards
To which nervous system do the cranial nerves belong?
PNS
What are the two primary modalities of cranial nerves?
sensory
motor
List the submodalities of cranial nerves and their associated functions. (3, 2)
sensory:
general sensory = innervation of skin, membranes, muscles joints
special sensory = innervation of special sensory organs
visceral sensory = innervation of viscera
motor:
somatic/branchial motor = innervation of skeletal muscle
visceral motor = innervation of smooth muscle
Differentiate between exteroceptive sensation and propioceptive sensation.
exteroceptive = pain, temperature, touch, pressure
propioceptive = joint position, tension of muscles
Generally speaking, what is the function of the general sensory modality of cranial nerves?
transmission of exteroceptive and proprioceptive sensation
Generally speaking, what is the function of the special sensory modality of cranial nerves?
transmission of unique sensations (vision, smell, hearing, balance, taste)
Generally speaking, what is the function of the visceral sensory modality of cranial nerves? (2)
transmission of diffuse pain from thoracic and abdominal viscera
transmission of internal stimuli isuch as blood pressure (baroreceptors) and O2 content (chemoreceptors) in blood
The somatic motor modality of cranial nerves refers to
innervation of structures that develop from somites
The branchial motor modality of cranial nerves refers to
innervation of structures that derive from pharyngeal arches
What kinds of fibers do cranial nerves carry?
cranial nerves only carry parasympathetic fibers — they do not carry sympathetic fibers
Where are the parasympathetic ganglia for parasympathetic fibers of cranial nerves located?
mostly located in head
Generally speaking, what is the function of the visceral motor modality of cranial nerves?
innervation of smooth muscle
List the 12 cranial nerves.
I - olfactory
II - optic
III - oculomotor
IV - trochlear
V - trigeminal
VI - abducent
VII - facial
VIII - vestibulocochlear
IX - glossopharyngeal
X - vagus
XI - accessory
XII - hypoglossal
The cranial nerves are numbered in what order?
from rostral to caudal
olfactory nerve (CN I): modality
special sensory = smell
olfactory nerve (CN I): innervated structure
olfactory organ = olfactory neurons in nasal cavity
olfactory nerve (CN I): foramen
cribiform plate
olfactory nerve (CN I): extracranial course (2)
short olfactory nerves
connection to olfactory bulb + tract within skull
optic nerve (CN II): modality
special sensory = vision
optic nerve (CN II): innervated structure
retina
optic nerve (CN II): foramen
optic canal
optic nerve (CN II): extracranial course
within orbit
(T/F) The optic nerve is only a cranial nerve by convention.
True. Structurally, it is an extension of the forebrain.
oculomotor nerve (CN III): modality (2)
somatic motor
visceral motor
oculomotor nerve (CN III): innervated structures (2 sets)
somatic motor = 4 of 6 extraocular muscles + levator palpebrae superioris
visceral motor = sphincter pupillae + ciliary muscles
oculomotor nerve (CN III): foramen
superior orbital fissure
oculomotor nerve (CN III): extracranial course
within orbit, splits into superior and inferior division
trochlear nerve (CN IV): modality
somatic motor
trochlear nerve (CN IV): innervated structure
one of the extraocular muscles (superior oblique)
trochlear nerve (CN IV): foramen
superior orbital fissure
trochlear nerve (CN IV): extracranial course
within orbit
What are the three primary branches of the trigeminal nerve (CN V)?
opthalmic nerve (CN V1)
maxillary nerve (CN V2)
mandibular (CN V3)
The trigeminal nerve is associated with which pharyngeal arch?
1st
opthalmic nerve (CN V1): modality
general sensory
opthalmic nerve (CN V1): innervated structures (4)
skin of forehead
scalp
orbit
parts of nasal cavity
opthalmic nerve (CN V1): foramen
superior orbital fissure
opthalmic nerve (CN V1): extracranial course
within orbit, where it gives off various branches
maxillary nerve (CN V2): modality
general sensory
maxillary nerve (CN V2): innervated structures (6)
skin of lateral external nose
inferior eyelid
anterior cheek
upper lip
palate
maxillary teeth
maxillary nerve (CN V2): foramen
foramen rotundum
maxillary nerve (CN V2): extracranial course
enters pterygopalatine fossa, where it gives off various branches
mandibular nerve (CN V3): modality (2)
general sensory
branchial motor
mandibular nerve (CN V3): general sensory innervated structures (5)
mucosa of anterior 2/3 of tongue
floor of mouth
mandibular teeth
external ear
buccal/parotid/temporal region of face
What innervates the muscles of mastication?
mandibular nerve (CN V3)
What are the four muscles of mastication?
masseter
temporalis
medial pterygoid
lateral pterygoid
mandibular nerve (CN V3): branchial motor innervated structures (5)
muscles of mastication
mylohyoid
anterior belly of digastric
tensor tympani
tensor veli palatine
mandibular nerve (CN V3): foramen
foramen ovale
mandibular nerve (CN V3): extracranial course
enters infratemporal fossa, where it gives off various branches
abducens nerve (CN VI): modality
somatic motor
abducens nerve (CN VI): innervated structure
one of the extraocular muscles (lateral rectus)
abducens nerve (CN VI): foramen
superior orbital fissure
abducens nerve (CN VI): extracranial course
within orbit, lateral
The facial nerve (CN VII) is associated with which pharyngeal arch?
2nd pharyngeal arch
facial nerve (CN VII): modalities
general sensory
special sensory
branchial motor
visceral motor
List the four major branches of the facial nerve and their innervated structures.
1st = greater petrosal nerve = pterygopalatine ganglion in pterygopalatine fossa → lacrimal gland
2nd = nerve to stapedius in tympanic cavity
3rd = chorda tympani = taste to anterior 2/3 of tongue
4th = auricular branch = somatic sensory for skin over mastoid process and within external acoustic meatus
What is the pathway for the chorda tympani?
through tympanic cavity into infratemporal fossa, where it merges w/ lingual nerve
What are the foramina associated with the facial nerve?
facial nerve enters skull through internal acoustic meatus, but leaves skull via various foramina
Describe the pathway of the facial nerve branches that supply muscles of facial expression.
exits skull through stylomastoid foramen and branches within parotid gland
vestibulocochlear nerve (CN VIII): modality
special sensory (hearing, balance)
vestibulocochlear nerve (CN VIII): innervated structures
specialized sensory cells in cochlea (hearing)
semicircular ducts/utricle/saccule of inner ear (balance)
vestibulocochlear nerve (CN VIII): foramen
leaves cranial cavity through internal acoustic meatus
vestibulocochlear nerve (CN VIII): extracranial course
does not leave skull
What are the branches of the vestibulocochlear nerve (CN VIII)?
vestibular nerve
cochlear nerve
The glossopharyngeal nerve (CN IX) is associated with which pharyngeal arch?
3rd pharyngeal arch
glossopharyngeal nerve (CN IX): modality
general sensory
special sensory (taste)
visceral sensory
branchial motor
visceral motor
glossopharyngeal nerve (CN IX): innervated structures (6)
stylopharyngeus
parotid gland (via tympanic nerve + otic ganglion)
tympanic cavity
carotid sinus + carotid body
mucosa of oropharynx
posterior 1/3 of tongue
glossopharyngeal nerve (CN IX): foramen
major portion of nerve exits through jugular foramen
What are the branches of the glossopharyngeal nerve? List their name and associated innervated structures.
1st = tympanic nerve = innervates tympanic cavity
2nd = carotid sinus nerve = innervates carotid sinus + body
3rd = small branchial motor nerve = innervates stylopharyngeus
Explain how the lesser petrosal nerve arises.
preganglionic parasympathetic fibers in tympanic plexus reorganize and form lesser petrosal nerve, which connects to otic ganglion
The vagus nerve is associated with which pharyngeal arches?
4th and 6th pharyngeal arches
vagus nerve (CN X): modality
general sensory
special sensory (taste)
visceral sensory
branchial motor
visceral motor
vagus nerve (CN X): innervated structures (6)
inferior pharynx
entire larynx
root of tongue
epiglottis
soft palate
thoracic and abdominal organs
vagus nerve (CN X): foramen
jugular foramen
List the important branches of the vagus nerve in the head and neck region. (3)
pharyngeal branches = muscles of soft palate + pharynx
superior laryngeal nerve = mucosa of larynx up to vocal folds + cricothyroid muscle
recurrent laryngeal nerve = mucosa of larynx inferior to vocal folds + internal laryngeal muscles
accessory nerve (CN XI): modality
somatic motor
accessory nerve (CN XI): innervated structures
sternocleidomastoid
trapezius
accessory nerve (CN XI): foramen
jugular foramen
hypoglossal nerve (CN XII): modality
somatic motor
hypoglossal nerve (CN XII): innervated structures
motor to most extrinsic and all instrinic muscles of tongue
hypoglossal nerve (CN XII): foramen
hypoglossal canal
Which four cranial nerves have preganglionic parasympathetic fibers as components?
III (oculomotor)
VII (facial)
IX (glossopharyngeal)
X (vagus)
What are the four parasympathetic ganglia of the head?
ciliary ganglion (CN III)
pterygopalatine ganglion (CN VII)
submandibular ganglion (CN VII)
otic ganglion (CN IX)
CN III: preganglionic pathway, ganglion, postganglionic pathway, target organs
preganglionic: inferior division of III
ganglion: ciliary
postganglionic: short ciliary nerves
target organs: ciliary muscles + sphincter pupillae
CN VII: preganglionic pathway, ganglion, postganglionic pathway, target organs
preganglionic: greater petrosal nerve + nerve of pterygoid canal
ganglion: pterygopalatine
postganglionic: maxillary nerve + zygomatic nerve
target organs: lacrimal gland + mucous glands of oral and nasal cavities
CN VII: preganglionic pathway, ganglion, postganglionic pathway, target organs [submandibular ganglion]
preganglionic: chorda tympani
ganglion: submandibular
postganglionic: lingual nerve
target organs: submandibular and sublingual salivary glands
CN IX: preganglionic pathway, ganglion, postganglionic pathway, target organs
preganglionic: tympanic + lesser petrosal nerves
ganglion: otic
postganglionic: auriculotemporal nerve
target organ: parotid gland
CN X: preganglionic pathway, ganglion, postganglionic pathway, target organs
preganglionic: vagus
ganglion: ganglia on viscera
postganglionic: direct branches to organs
target organs: thoracic and abdominal viscera
Parasympathetic fibers in the head are usually distributed along cranial nerves. How are sympathetic fibers distributed in the head?
they follow the arterial supply to the head
Where do all preganglionic sympathetic nerve fibers arise?
in thorax, at levels T1 to L2 of spinal cord
Broadly speaking, what is the function of the vagus nerve?
parasympathetic innervation to abdominal viscera, heart, and lungs
List the four major branches of the vagus nerve and their associated functions.
superior laryngeal nerve
external branch of superior laryngeal nerve = motor innervation of cricothyroid
internal branch of superior laryngeal nerve = sensory innervation of laryngeal mucosa
recurrent laryngeal nerve = muscles of larynx
Describe the positioning of the recurrent laryngeal nerve.
right side hooks around right subclavian artery
left side hooks around aorta
Which cranial nerves pass through the cribiform plate?
olfactory nerve (CN I)
Which cranial nerves pass through the optic canal?
optic nerve (CN II)
Which cranial nerves pass through the superior orbital fissure?
oculomotor nerve (CN III)
trochlear nerve (CN IV)
opthalmic nerve (CN V1)
abducens nerve (CN VI)
Which cranial nerves pass through the foramen rotundum?
maxillary nerve (CN V2)
Which cranial nerves pass through the foramen ovale?
mandibular nerve (CN V3)
Which cranial nerves pass through the internal acoustic meatus?
facial nerve (CN VII)
vestibulocochlear nerve (CN VIII)
Which cranial nerves pass through the jugular foramen?
glossopharyngeal nerve (CN IX)
vagus nerve (CN X)
accessory nerve (CN XI)
Which cranial nerves pass through the hypoglossal canal?
hypoglossal nerve (CN XII)
What is the mnemonic to remember whether a cranial nerve as a sensory, motor, or mixed modality?
In the oral/nasal cavities, the greater petrosal nerve (first branch of facial nerve) runs with which other nerve? How does this nerve further branch?
runs with zygomatic nerve to mucosal glands
zygomatic nerve further branches to give lacrimal nerve, which innervates lacrimal glands
Where does the greater petrosal nerve synapse?
pterygopalatine ganglion
The chorda tympani (third branch of facial nerve) can be seen running alongside with which other nerve? Where do these two nerves end up?
hitchhikes with lingual nerve to synapse at submandibular ganglion, thus innervating submandibular and sublingual glands
What are the targets of the branchial motor modality of the facial nerve? (4)
muscles around ear (via posterior auricular nerve)
posterior belly of digastric
stylohyoid
muscles of facial expression
Which two cranial nerves have all five major modalities?
glossopharyngeal
vagus
The tympanic plexus associated with the glossopharyngeal nerve eventually converges into
the lesser petrosal nerve
Describe the pathway of the lesser petrosal nerve. (2)
synapses at otic ganglion
runs alongside auriculotemporal nerve to parotid gland
What provides motor innervation to the cricothyroid?
vagus nerve
