CN 5 Flashcards
Largest CN?
Trigeminal
CN has a _____ motor portion and ______ sensory
Small, large
V1-ophthalmic- M/S?
Sensory
V2-maxillary-M/S?
Sensory
V3-mandibular-M/S?
Both
CN fibers originate in _____ _____ and descend in _____ ______ to ______ nucleus in the ________
Precentral gyrus
Descend in corticobulbar tract
To motor nucleus
Trigeminal motor nucleus receives projections from where?
Both cerebral hemispheres
Motor root exits _______ ______ and passes beneath _____ _____ and exits skull through _____ _____
Lateral pons
Trigeminal ganglion
Foramen ovale
What does the motor (V-3) pathway supply?
Muscles of mastication (temporalis, masseter, med/lat pterygoid)
Tensor tympani, tensor evil palatine, mylohyoid, anterior belly of digastric
Because trigeminal motor nucleus receives projections from both hemispheres, if there was a lesion on one side, what will the affects be?
Not much affect-redundancy
Function of temporalis
Close jaw
Retract
Internal/medial pterygoid function
Syncs: close and protrude
Unilateral: side to side jaw movement
Masseter
Close and protrude
External/lateral pterygoid
Sync: open and protrude jaw
Unilateral: pulls mandible contralaterally
What does unilateral trigeminal motor weakness cause during opening?
Jaw to deviate toward the side of weakness
If you had a weak right pterygoid what would you find?
Jaw deviates to the right on opening
Inability to move jaw to the left on command
Unilateral weakness of CN5 signifies a lesion potentially where?
- brain stem (dismally)
- trigeminal ganglion
- motor root of CN 5
Will there be weakness with UMN lesion of CN5?
No
Besides muscle weakness, what else might you find with a LMN lesion of CN 5
Atrophy
Fasciculations
Decreased jaw jerk reflex
Atrophy of masseter
Flattening of jowl
Atrophy of temporalis
Hallowing of the temple on ipsilateral Sid
Severe bilateral weakness of muscles of mastication with inability to close mouth suggest
Bilateral corticobulbar lesions
- motor neuron disease (ALS)
- neuromuscular transmission disorder (MG)
- myopathy
CN V1,2,3 converge on trigeminal ganglion aka _____ aka ______ ganglion located in _____ ______
Semilunar
Gasserian
Meckel’s cave
After converging at the trigeminal ganglion, a large sensory root of trigeminal nerve enters brainstem at the _______. Some _____ their branches and terminate on the ____ ______ nucleus and others ______ and terminate in the _____ _____
Pons
Ascend and terminate on main sensory nucleus
Descend and terminate in the spinal nucleus
Fibers with what sensations terminate in the main sensory nucleus
Touch and pressure
Fibers with what sensations pass to the spinal nucleus
Pain and temperature
From the main sensory and spinal nuclei axons ascend in the _____ and _____ ______ ______ to the ____ ____ ___ _____ nucleus
Dorsal and ventral trigeninothalamic tract
Ventral posterior medial (VPM) thalami nucleus
Once ascending to the VPM, fibers project to the _____ cortex in the ____ ___ ____
Sensory
Post central gyrus
What does CN v-1 supply?
Bridge and side of nose upper eyelid forehead scalp to vertex eyeball-superior 1/2 cornea Lacrimal gland Nasal septum Lateral wall of nasal cavity Ethmoid sinus Tentorium cerebelli
What does CN 5-2 supply
Cheek Lateral forehead Side of nose Upper lip Upper teeth/gums Palate Nasopharynx Posterior nasal cavity Meninges of anterior/middle cranial fossa
What does CN 5-3 sensory part supply
Inner cheek Temple Lateral scalp EAM tympanic membrane TMJ Mandible Lower teeth/gums Anterior 2/3tongue (GEN SENSORY) Lower lip Chin Anterior and middle cranial fossa
Does CN 5-3 supply sensory innervation to the angle of the jaw?
No
Sensory fibers from where synapse in the inferior (caudal) aspect of the spinal nucleus?
pre-auricular
Sensory fibers from where synapse in the middle aspect of the spinal nucleus?
Middle ring of the face
Sensory fibers from where synapse in the superior/rostral aspect of the spinal nucleus?
Perioral ring
If patient presents with unilateral or bilateral onion skin distribution of sensory loss it suggests a lesion where?
Spinal nucleus.
Outer face—lower parts of spinal nucleus
Inner face—upper part of spinal nucleus
Lesions distal to trigeminal ganglion will involve what?
Isolated divisions ex: V1,2,3
Lesions central to the trigeminal ganglion will affect what
All 3 branches of sensory distribution of CN 5
Lesions involving the spinal nucleus of the brainstem will cause what
Sensory dysfunction in an “onion skin” appearance
CN 7 function types
Parasympathetic
Visceral sensory
General somatosensory
Parasympathetic innervation to what CN7
Tears and saliva
Visceral sensory function of CN7
Taste (ant 2/3)
CN 7. Main trunk carries ____ _____ fibers that control ____ ____ and smaller branchL ____ ____ carries fibers for ______, _____ ____, and _____ _____
Brachial motor that control facial expression
Nervous intermedius
Parasympathetic, visceral sensory and general somatosensory function
CN 7 path.
Primary motor cortex in ____ _____. ________ tracts descend to ____ _____ in ______ and synapse with _______
Precentral gyrus in corticobulbar tracts
Descend to facial nucleus in pons
Synapse with LMNs’ (facial N)
Facial N exits ____ at ______ _____ and transverse ____ _____ and enters the ____ ____ ____ and travels in the _____ _____ with CN ____
Brainstem at cerebellopontine angle
Transverse subarachnoid space
Enter the internal AM
Travels in auditory canal with CN 8
After CN 7 travels in auditory canal with CN8, it runs inferiorly in the ____ ___. The main portion then ______ the skull through the ______ ____ and passes through the _____ _____. Here it divides into _____ major ____ _____ branches to supply ______ of facial expression
Facial canal
Exits skull through stylomastoid foramen
Pass through parotid gland
Divides into 5 brachial motor branches
Supply muscles of facial expression
What muscles of facial expression does CN 7 supply
- frontalis
- orbicularis oculi/oris
- buccinator
- platysma
- posterior/digastric
- stapedius muscle
What does the platysma do
Frown
What does the stapedius muscle do
Dampens movement of middle ear ossicles
-protective mechanism of sound at loud events
Preganglionic fibers of CN7 originate in the ____ ____ ____ and branch into ___ nerves: ____ ___ and _____ ____
Superior Salvatore nucleus
- Greater petrosal
- Chorda tympani
Greater petrosal nerve goes through ___ ganglion and has ____ _____ fibers to the _____ ___ and ____ ___
Sphenopalatine ganglion
Postganglionic parasympathetic fibers to lacrimal gland and nasal mucosa
Chorda tympani exits skull through ____ ____ and joins ___ ___ to reach ______ ganglion. Has ____ ____ supply to ____ and ____ _____ glands
Petrotympanic fissure
Joints lingual nerve to reach submandibular ganglion
Postganglionic parasympathetic supply to submandibular and sublingual salivary glands
Submandibular and sublingual glands receive parasympathetic innervation from? And sympathetic?
Para: chorda tympani
Symp: superior cervical ganglion and carotid plexus
Sympathetic innervation causes what from submandibular/sublingual glands?
Vasoconstriction and scant, thick, mucoid secretion low in enzyme
Lesion in internal acoustic meatus would cause what.
Look up! Slide 42
Visceral sensory pathway for CN7. ______ _____ carries fibers from ant 2/3 tongue that has cell bodies in the _____ ganglion. It synapses with secondary neurons in the ____ _____/_____ _____ and ascends via ____ ______ tract where it reaches the _______ and these neurons protect to _____ ___ ____ in the ______ gyrus
Chorda tympani
Geniculate
Nucleus solitaries/gustatory nucleus
Ascends via central tegmental tract and reaches the VPM nucleus
Project to cortical taste area in the postcentral gyrus
General somatosensory pathway of CN7. Primary sensory neurons located in _____ ganglion and synapse in the _____ nucleus where they then continue to the ______ cortex in the ______ gyrus
Geniculate
Synapse in trigeminal nucleus
Somatosensory cortex in the postcentral gyrus
Where does the facial nerve provide somatic sensation
Region near the EAM
UMN lesion in CN7 cause what?
Contralateral face weakness sparing the forehead
**recall upper face has both hemispheres contributing and unaffected hemisphere can compensate
Where could the lesion be if there is left sided facial weakness—sparing the forehead?
CN 7 UMN lesion on the R
Where could the lesion be if the entire left side of the face is weak?
CN7 LMN lesion on the left
What part of the face has innervation from both hemispheres?
Upper part—forehead
Why UMN lesion results in sparing of the forehead, and LMN lesion doesn’t
What pathology cause loss of facial movement on entire side of face
Bell’s palsy-LMN issue
What pathology causes facial weakness sparing the forehead?
Stroke—UMN lesion
What should be considered if patient can raise both eyebrows?
Stroke
Two types of lesions of CN7
Peripheral/nuclear/infranuclear
(Aka at nucleus or below)
Central/supranuclear
Where is the lesion in CN7 in a peripheral lesion?
From the facial nucleus and distal
S/s of peripheral/nuclear/infranuclear lesion of CN7
Ipsilateral to lesion
- complete facial paralysis
- smoothening of brow
- difficulty closing eye
- flat nasolabial fold
- drooping of mouth
Where might the lesion be in a central/supranuclear lesion of CN 7
Lesion of motor cortex or corticobulbar tracts
S/s of central/supranuclear lesion of CN7
- contralateral to lesion
- lower portion of face
- spare forehead/can raise eyebrow
- drooping mouth
- flattened nasolabial fold
The 5Ds. 3Ns, and A for stroke
D: dysarthria, dysphasia, diplopia, dizziness, drop attacks
N: numbness, nystagmus, nausea
A: Ataxia
Aguesia
Complete loss of taste
Cause of aguesia
Olfaction dysfunction (Vit A, b6,12,zinc,copper def)
- viral infection
- aging
- toxic
- metabolic
Unilateral deficits in taste causes?
Lesions of nucleus solitarious or facial nerve
** if peripheral lesion it must be proximal to stylomastoid foramen because if distal would only affect muscles
Lesion distal to stylomastoid foramen would cause what>
Weakness of muscles of facial expression
