Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuroscience > Cranial Nerve Lesions > Flashcards

Cranial Nerve Lesions Flashcards

1
Q

Corticonuclear projections

A

. From cerebral cortex to brainstem nuclei
. Arise from neurons in PMC (area 6), M-1 (4) and somatosensory cortex (3,1,2,5) cortices
. Projections affect voluntary control of mm. Innervated by strainstem nuclei
. Bilateral except. CN VII and XII

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

CN III GSE component

A

. Located in midbrain, axons of LMNs exit oculomotor nucleus to enter ipsilateral oculomotor n.
. Innervation is to ipsilateral extraocular mm. (SR, IR, MR, IO, and levator palpebrae superioris)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Is there corticonuclear projections to brainstem motor nuclei of CN III, IV, and VI?

A

No

. Cerebral cortex influences these through connections w/ PPRF (gaze) centers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

GVE component of CN III

A

. Preganglionic parasympathetics in Edinburgh-westphal nucleus exit brainstem w/ GSE fibers
. Synapse on postganglionic neurons in ciliary ganglion in the orbit
. Postganglionic fibers innervate the sphincter pupillae and ciliary ganglion in the orbit
. Postganglionic fibers innervate sphincter pupillae and ciliary mm. To constrict pupil and change lens shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Mydriasis w/ no response to light may be a clinical sign of ____

A

Pressure on CN III in its course from midbrain to orbit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Lesions of CN III (LMN or n.)

A

. Ptosis
. Lat. strabismus (eye abducted and inf. Rotated from unopposed SO/LR)
. Mydriasis
. Loss of pupillary light reflex and accommodation reflex from denervation of sphincter pupillae m.
. Inability to laterally gaze to side opposite the lesion w/o diplopia (denervation of MR)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

CN IV GSE component

A

. In midbrain, LMNs decussate and exitbrainstem on dorsal side
. Innervation is contralat. SO m.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Lesions of CN IV

A

. Isolated lesions uncommon
. Affected eye is somewhat elevated at rest due to unopposed IO
. Patient experiences diplopia in vertical plane
. Tests for it: have patient look medially and then inf. To isolate SO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

GSE component of CN VI

A

. In caudal pons
. Axons of LMNs exit brainstem at pontomedullary junction
. Innervation is to ipsilateral LR m.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Lesions fo CN VI

A

. LMN in pons or n.
. Med. strabismus (affected eye is adducted due to unopposed action of MR)
. Inability to laterally gaze to side of lesion w/o diplopia
. Lesion in pons will always affect ipsilateral PPRF causing gaze preference away from side of lesion due to PPRF involvement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

SVE component of CN V

A

. In pons
. Motor trigeminal nucleus has axons of LMNs exiting in trigeminal motor root of ipsilateral trigeminal n.
. Innervation to ipsilateral mm. Of mastication, tensor veli palatini, tensor tympani, mylohyoid, and ant. Belly of digastric mm.
. Corticonuclear projections are bilaterally equal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Lesion to trigeminal motor component

A

. Jaw protrudes to side of lesion from unopposed action of healthy pterygoids on opposite side
. Jaw-jerk reflex absent due to paralysis of mm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Corneal (blink) reflex

A

. Unilateral stimulation of cornea results in reflex blinking and eye closure
. Afferent limb: CN V1 to spinal trigeminal nucleus
. Central connections: bilat. Projections to facial motor nuclei
. Efferent limb: facial nn. To orbicularis oculi mm.
. Direct response: stimulated eye closes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Lacrimal (tear) reflex

A

. Unilateral stimulation of cornea (pain) results in tear production
. Afferent limb: CN V1 to spinal trigeminal nucleus
. Central connections: bilat. Projections to sup. Salivatory nuclei (preganglionic parasympathetic (GVE) neurons) in pons
. Efferent limbs: facial nn. To pterygopalatine ganglion via the greater petrosal n. To lacrimal gland for tear production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

SVE component of CN VII

A

. Located in caudal pons
. Axons of LMNs exit facial motor nucleus to enter ipsilateral motor root of facial n.
. Innervation to mm. Of facial expression, stapedius, stylohyoid, and post. Belly of digastric mm.
. W/in pons, the facial motor nucleus receives bilat. Corticonuclear projections for innervation of upper facial mm. (Sup. To and orbicularis oculi mm.)
. Facial motor nucleus receives contralat. Corticonuclear projections only for innervation of lower facial mm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

GVE component of CN VII

A

. Preganglionic parasympathetic located in sup. Salivatory nucleus in pons
. Axons leave nucleus to enter ipsilateral facial n.
. Postganglionic neurons located in pterygopalatine and submandibular ganglia
. Innervation is mucous glands of oral and nasal cavities, lacrimal gland, and submandibular and sublingual salivary glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

CN VII LMN lesion effects

A

. LMN lesions cause complete ipsilateral face flaccid plegia, fasciculations may be present

18
Q

CN VII Lesion peripheral to stylomastoid foramen

A

. Lesion to stylomastoid foramen: plegia of face mm. (Bell’s palsy)

19
Q

CN VII lesion in facial canal prox. To chorda tympani junction

A

. Lesion in facial canal prox. To junction w/ chorda tympani (same as Bell’s w/ loss of taste over 2/3 tongue)

20
Q

CN VII lesion in facial canal prox. To origin of n. To stapedius m.

A

. Plegia of mm., of facial expression
. Loss of taste over ant. 2/3 tongue
. Hyperacousis

21
Q

CN VII lesion prox. To genticulate ganglion

A

. Plegia of mm. Of facial expression
. Loss of taste over ant. 2/3 tongue
. Hyperacousis
. Absence of lacrimation

22
Q

CN VII UPM lesion

A

. Paresis of contralat. Lower face ONLY
. Disuse atrophy over time
. No fasciculations

23
Q

Innervation of motor component of face

A

. Upper face is bilaterally innervated
. Patient w/ unilateral cortical lesion will still be able to wrinkle brow and close eyes
. Lower face is not bilaterally innervated and will lose mobility in contralateral side of face to lesion
. If patient is told something funny they can smile bilaterally though due to processing in hypothalamus and limbic system

24
Q

SVE component of CN IX

A

. In nucleus ambiguus in medulla
. Axons of LMNs enter ipsilateral CN IX
. Innervation to stylopharyngeus m.
. Corticonuclear projections are bilateral

25
Q

GVE component of CN IX

A

. Preganglionic parasympathetic neurons from inc. salivatory nucleus enter ipsilateral CN IX, course through tympanic plexus and less petrosal n. To otic ganglion in infratemporal fossa
. Postganglionic join auriculotemporal branch of mandibular n. And provide secretomotor innervation to parotid gland

26
Q

Lesions of CN IX LMNs or actual nerve

A

. Very rare
. Difficult to test stylopharyngeus alone so use gag reflex to test
. Lesion of n. Or inf. Salivatory nucleus causes loss of parotid gland secretions

27
Q

SVE component of CN X

A

. In nucleus ambiguus, LMN axons enter ipsilateral vagus n.
. Innervation to soft palate, mm. Of pharynx and larynx
. Corticonuclear projections are bilateral

28
Q

GVE component of CN X

A

. Preganglionic parasympathetic neurons in dorsal motor nucleus of vagus in medulla enter ipsilateral vagus n.
. Postganglionic neurons in ganglia in pharynx, larynx, thoracic, and abdominal viscera
. Innervation to mucous membranes of pharynx and larynx and to smooth m. And glands of thoracic and abdominal viscera
. Efferent limb of carotid sinus reflex for controlling HR is carried by these fibers in nucleus ambiguus

29
Q

Unilateral lesion of CN X

A

. Often in conjunction w/ CN IX lesion due to proximity
. Ipsilateral plegia of soft palate (droops) and deviation of uvula to intact side
. Ipsilateral vocal cord palsy causing hoarseness and coughing early on (then adapts over time)
. Visceral signs of unilateral lesion generally negligible bc of bilateral distribution of vagal fibers in periphery

30
Q

Bilateral lesion of CN X

A

. Vocal cord plegia may lead death by asphyxiation
. Lesions involving GVE fibers in nucleus ambiguus may accelerate HR to point of death
. Upper motor neurons lesion of corticonuclear projections are difficult to detect due to bilateral innervation

31
Q

SVE component of CN XI

A

. In ventral horn of spinal cord at C1-5 levels
. Axons of LMNs enter ipsilateral CN XI
. Rootlets emrge from lat. aspect of spinal cord btw dorsal and ventral roots
. Join to form common trunk lateral to spinal cord
. The n. Enters skull via foramen magnum and exits through jugular foramen
. Innervation to ipsilateral SCM and trap mm.

32
Q

Lesions of CN XI

A

. Ipsilateral should sag and inability to elevate upper limb above horizontal plane due to loss of trap m.
. Paresis or plegia when pointing chin away from side of lesion esp. against resistance
. Chin points to side of lesion due to loss of SCM and unopposed action o intact SCM on other side

33
Q

GSE component of CN XII

A

. In hypoglossal nucleus in medulla
. Axons of LMNs enter ipsilateral hypoglossal n.
. Innervation is to ipsilateral intrinsic and extrinsic mm. Of tongue (except palatoglossus)
. Corticonuclear projections are contralat.

34
Q

LMN lesion of CN XII

A 
. LMN in medulla or actual n. Issue 
. Plegia of ipsilateral tongue mm. 
. Deviation of tongue to side of lesion due to unopposed action of interact genioglossus m. 
. Atrophy of ipsilateral mm. 
. Fasciculations ipsilateral to lesion
35
Q

CN XII UMN lesions of corticonuclear to contralateral hypoglossal nucleus

A

. Contralat. Paresis in tongue mm.
. Deviation of tongue opposite to lesion due to unopposed genioglossus
. Disuse atrophy over time
. No fasciculations

36
Q

Hallmark of brainstem lesions

A

. Involves CNs and corticospinal tract where they course in close proximity

37
Q

Alternating hemiplegias

A

. Involve lesion of CN and CST
. Assoc. w/ paramedian lesions that interrupt CST and a CN exiting brainstem at that level
. Ipsilateral LMN signs for CN
. Contralat. UMN signs for CST

38
Q

Alternating hypoglossal hemiplagia

A

. Medial medullary syndrome
. Assoc. w/ infarct of paramedian branch of ant. Spinal a.
. Involves med. portion of ventral medulla
. LMN signs for ipsilateral hypoglossal n.
. Contralat. UMN for ipsilateral CST (rostral to decussation)
. Contralat. Loss of tactile sensation and conscious proprioception due to loss of ipsilateral medial lemniscus

39
Q

Alternating abducens hemiplegia

A

. Assoc. w/ infarct of pontine branches of basilar a.
. Involve seed. Portion of ventral caudal pons
. LMN signs for ipsilateral abducens
. Contralat. UMN signs for ipsilateral CST

40
Q

Alternating oculomotor hemiplegia

A

. Weber’s syndrome
. Assoc. w/ infarct of basal branch of post. Cerebral a.
. Involves med. portion of enteral midbrain
. LMN signs for ipsilateral ocumotor n.
. contralat. UMN signs for ipsilateral CST

Neuroscience (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions