Cranial Nerves (minus V and VII) Flashcards
What ar the cranial nerve names and their brain associations?
Forebrain: CN I (olfactory); CN II (optic)
Midbrain: CN III (oculomotor)
CN IV (trochlear)
Pons: CN V (trigeminal)
CN VI (abducens)
CN VII (facial)
CN VIII (vestibulocochlear)
Medulla oblongata: CN IX (glossopharyngeal)
CN X (vagus)
CN XI (accessory)
CN XII (hypoglossal)
Which ones have parasympathetic fibers? What kind? Where do they synapse?
CN III (oculomotor) to ciliary ganglion
CN VII (facial) to submandibular and pterygopalatine
CN IX (glossopharyngeal) to otic
CN X (vagus) to the lower body
all have pregangionic parasympathetic fibers
- The cell bodies of all general sensory neurons are located in ganglia of which cranial nerves?
- These ganglia are analogous to the _____.
- What kind of neurons are they?
- Which ones have taste neurons?
- (V) Trigeminal nerve
(VII) Facial nerve*
(IX) Glossopharyngeal nerve*
(X) Vagus nerve * - dorsal root ganglia of the spinal cord
- (pseudounipolar neurons)
- *have taste
Where are motor neurons located?
What kind of neurons are they?
in all cranial nerves in NUCLEI in the brainstem (analogous to the ventral horn of the spinal cord)
multipolar neurons
The _____ innervate all of the structures derived from the branchial arches. They are?
Skeletal muscles derived from branchial arches are said to be innervated by ____ fibers, as opposed to all other muscles which are innervated by ____ fibers.
branchiomeric cranial nerves
Trigeminal nerve (V) Branchial arch 1 Facial nerve (VII) - Branchial arch 2 Glossopharyngeal nerve (IX) - Branchial arch 3 Vagus nerve (X) - Branchial arches 4 - 6 Accessory nerve (XI) - Branchial arches beyond arch 6?
**so all the ones with general sensor PLUS accessory nerve
branchial motor or special visceral efferent; general somatic efferent
This nerve supplies a branchial arch, but has no general sensory neurons in its ganglia.
Accessory (CN XI) supplies branchial arches >6
These nerves have both taste and general sensory neurons AND supply branchial arches.
(VII) Facial nerve (2)
(IX) Glossopharyngeal nerve (3)
(X) Vagus nerve (4-6)
What are the ocular muscles and what supplies them?
SO4 LR6 AR3
superior oblique eye muscle - CN IV (trochlear)
lateral rectus eye - CN VI (abductens)
all the rest - CN III (occulomotor)
Levator palpebrae superioris; Superior, Medial, and Inferior rectus eye muscle; Inferior oblique eye muscle
Trace the course of CN III, pay close attention to the parasympathetic fibers.
Oculomotor nerve:
emerges from ventral aspect of midbrain
proceeds through lateral wall of cavernous sinus
enters orbit thorugh superior orbital fissure (with CN IV and VI)
divides into superior and inferior division
parasymp component is in inferior division and leaves as parasympathetic (motor) root of the ciliary ganglion; goes to ciliary ganglion and sypanses; postgang fibers travel as short ciliary nerves to eyeball
Describe control of the pupil.
Parasympathetic: short ciliary nerves from ciliary ganglion supply ciliary muscle (change lense for near vision) and sphincter of the pupil (controls light)
Sympathetic: dilator of the pupil is controled by postgang fibers from superior cervical ganglion
Describe CN VIII.
Vestibulocochlear nerve
has two divisions: vesibular (sensory re: balance and equilibirium) and cochlear (sensory re: hearing)
enters internal acoustic meatus with CN VII (facial)
What kind of fibers does CN IX have?
Glossopharyngeal
- branchial motor / special visceral
- pregang. parasym
- visceral sensory (carotid body/sinus)
- special sensory (taste)
- general sensory
What are the branches of CN IX?
- tympanic
- carotid nerve (carotid sinus/bodies)
- motor to stylopharyngeus muscle (only muscle)
- pharyngeal and tonsillar branches (sensory)
- lingual branch (sensory/taste to posterior 1/3 of tongue)
Describe the course of CN IX out of the skull.
- emerges from medulla oblongata from post olivary sulcus
- has two sensory ganglia (sup, inf) in jugular foramen
- exits skull in jugular foramen with CN X, XI
What is an example of referred pain via CN IX?
How do you test if there is a lesion of CN IX? Why not a gag reflex test?
middle ear pain from tonsillitis
taste test in posterior 1/3 of tongue; you can try to use gag refelx by stroking posterior 1/3 of tongue, if vagus is still in tact. however, if vagus is also compromised, IX may induce gag reflex but pharyngeal muscles are mostly innervated by vagus so they will not be functional, thus is there no gag b/c afferent or efferent is faulty?
What types of fibers are in CN X?
VAGUS NERVE
- branchial motor / special visceral
- pregang. parasym
- visceral sensory
- special sensory (taste)
- general sensory
What are the branches of CN X in the head/neck?
- meningeal (sensory to dura mater)
- auricular (sensory to ear)
- pharyngeal
- carotid (sinus/bodies)
- aortic (baroreceptors/chemoreceptors)
- superior laryngeal branch
- recurrent laryngeal branch
Describe the innervation of the pharynx and palate.
Pharyngeal plexus contains pharyngeal branch of IX, X and postgang. sympathetic fibers from superior cervical ganglion
motor: pharynx mainly X except stylopharyngeus (CN IX)
palate mainly X except tensor of the palate (V3)
sensory: contributions from VII, IX, X
Describe the superior laryngeal branch of X.
Divides into:
(1) internal largyngeal (sensory+taste)
- runs with superior laryngeal artery; pierces thyrohyoid membrane
- supplies larynx, epiglottis, valleculae
(2) external laryngeal (motor)
- runs with superior thyroid artery
- supplies cricothyroid muscle (only larynx muscle NOT supplied by recurrent laryngeal nerves)
What are symptoms and tests for lesion in X?
Symptoms: increased pulse rate, constant nausea, decreased rate of respiration, a sensation of suffocation, and a hoarse, low voice, difficulty swallowing.
Tests used: gag reflex (contraction of the pharyngeal constrictors upon touching the pharyngeal wall or the base of the tongue), faulty movement of the uvula, and a paralyzed vocal cord on the affected side as seen with a laryngoscope.
Trace CN XI.
Accessory nerve
- emerges from C1-5 between D and V rootlets
- ascends/ enters skull via foramen magnum
- exits skull via jugular foramen
- runs down and lateral to superior border of SCM either pierces or runs deep to SCM, supplying it
- continues down and lateral to trapezius IN THE INVESTING FASCIA (so superficial), supplying it
Symptoms of lesion of XI?
Accessory nerve; innervates sternocleidomastoid and trapezius
Lesion of this nerve will result in weakness in turning the head to the opposite side as well as sagging of the shoulder.
- What kind of fibers does CN XII have?
- Trace it.
- What hitchhikes on it?
- What does it supply?
- The hypoglossal nerve is a pure motor nerve.
- It emerges from the medulla oblongata from the pre-olivary sulcus. It leaves the skull via the hypoglossal canal.
- Branches of VR C1 hitchhike on it.
- The hypoglossal nerve supplies all muscles of the tongue with the exception of the palatoglossus (vagus nerve)
Symptoms of lesion of XII?
Paralysis of the tongue. Sensations are still there.
When tongue is stuck out, it will turn to the side of the lesion due to genioglossus muscle from unaffected side.
Describe CN I.
olfactory nerve
- contains special sensory fibers for smell
- specialized bipolar neurons in the olfactory mucosa on the top of the nasal cavity send axons through the cribriform plate to the olfactory bulb of the forebrain
Describe CN II.
The optic nerve
- travels through the optic canal along with the ophthalmic artery
- contains special sensory fibers for sight.
Describe the tympanic nerve and plexus.
tympanic nerveis a branch of the glossopharyngeal nerve (IX)
- enters tympanic cavity (middle ear)
- its pregang. parasym and sensory fibers mix with postgang. symp. fibers from superior cervical ganglion to form tympanic plexus
- all pregang. parasym. fibers reconverge as lesser petrosal nerve
- exit temporal bone via hiatus of the lesser petrosal nerve
- leaves skull via foramen ovale and enters infratemporal fossa
- synapses at otic ganglion
- postgang. parasym fibers join auriculotemporal nerve (V3) to go to parotid gland (saliva)
Describe the parasympathetic fibers of CN III and CN IX.
CN III (oculomotor): part of inferior division, leaves as parasympathetic (motor) root of the ciliary ganglion –> synapse on ciliary ganglion –> leave as short ciliary nerves to get to cilary muscles/sphincter of pupil
CN IX (glossopharyngeal): part of tympanic branch/plexus, exits plexus as lesser petrosal nerve, goes through hiatus of lesser petrosal nerve and foramen ovale –> synapse on otic ganglion –> hitchhike on auriculotemporal nerve (V3) to get to parotid gland
What is the ciliary ganglion near?
What is the otic ganglion near?
Optic nerve (CN II)
Mandibular nerve (CN V3)
What are the nerves and the arteries to the Larynx?
Nerves:
(1) superior laryngeal (X) –> internal branch provides sensory, external branch provides motor to circothyroid
(2) recurrent laryngeal (X) provides motor to the rest
Artery:
(1) Superior laryngeal (from sup thyroid <- ext. carotid)
(2) inferior laryngeal (from inf. thyroid <- thyrocervical trunk)
What nerves and arteries supply the pharynx?
Nerves: ALL FORM THE PHARYNGEAL PLEXUS
(1) Pharyngeal branch ohf vagus (main supply)
(2) stylopharyngeal branch of glossopharyngeal
(3) postgang. sympathetic from sup. cervical ganglia
Artery:
(1) ascending pharyngeal (from ext. carotid)
(2) pharyngeal branches (from inf. thyroid)
What nerves and arteries supply the auricular area?
Nerves:
(1) great auricular (from cervical plexus; skin)
(2) posterior auricular (facial nerve)
(3) auricular branches (vagus; sensory)
(4) auriculotemporal (trigeminal V3)
Arteries:
(1) posterior auricular (ext. carotid)
