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Anatomy (S2)(Unit 1) > Neurology (01/30) Cranial Nerves III, IV, and VI > Flashcards

Neurology (01/30) Cranial Nerves III, IV, and VI Flashcards

1
Q

separates the motor and sensory pathways in the brainstem

A

sulcus limitans

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2
Q

the difference between the nuclear arrangement of the brainstem and the spinal cord is that the brainstem is ______

A

discontinuous

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3
Q

Cranial nerves III, IV, and VI are all ____ ____ nerves

A

somatic motor

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4
Q

what are the two axon types for CN III?

A
  • somatic motor

- autonomic

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5
Q

where is the CNS origin for the somatic motor axon of CN III?

A

oculomotor nucleus

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6
Q

where is the CNS origin for the autonomic axon of CN III

A

edinger-westphal nucleus

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7
Q

what muscles are innervated by the somatic motor axon of CN III

A
  • superior, inferior, medial recti
  • inferior oblique
  • levator palpebrae superioris
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8
Q

what muscles are innervated by the autonomic axon of CN III

A
  • pupillary sphincter
  • pupillary ciliary

(after a synapse in the parasympathetic ganglion)

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9
Q

both CN IV and VI’s axon types are ____ ____

A

somatic motor (only! no autonomic)

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10
Q

superior oblique is responsible for what type of eye movement from neutral position?

A

internal rotation (intorsion)

*look down

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11
Q

inferior oblique is responsible for what type of eye movement from neutral position?

A

external rotation (extorsion)

*look up

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12
Q

at what level of the midbrain does the oculomotor nerve (III) exit?

A

upper midbrain

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13
Q

at what level of the midbrain does the trochlear nerve (IV) exit?

A

lower midbrain (crosses ipsilaterally just as it leaves)

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14
Q

at what level of the midbrain does the abducens nerve (VI) exit?

A

lower pons

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15
Q

CN III innervates the levator palpebrae superioris muscle ______ (ipsilaterally, bilaterally, contralaterally)?

A

bilaterally

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16
Q

CN III innervates the superior rectus muscle ______ (ipsilaterally, bilaterally, contralaterally)?

A

contralaterally

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17
Q

regarding CN III, the column supplying medial rectus, inferior oblique, inferior rectus are projected to ______ (ipsilaterally, bilaterally, contra laterally) muslces?

A

ipsilateral

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18
Q

regarding CN III, the edinger-westphal nucleus is a preganglionic parasympathetic projection to the _______ ciliary ganglion, and innervates ______ and ______

A
  • ipsilateral
  • pupillary sphincter
  • pupillary ciliary
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19
Q

what are the 7 results of a CN III injury?

A
  • ipsilateral eye to lesion deviates laterally
  • cannot move eye medially
  • vertical movement is impaired
  • diplopia
  • ptosis
  • mydriasis
  • pupil does not constrict or focus for near vision
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20
Q

in an injury to CN III, why does the ipsilateral eye deviate laterally?

A

bc the medial rectus is weak and the lateral rectus is no unopposed so pulls it in that direction (lateral strabismus)

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21
Q

in an injury to CN III, why is vertical movement of the eye impaired?

A

bc there is now a weak superior and inferior recti mm as well as the IPSILATERAL inferior oblique

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22
Q

what is diplopia? (happens during injury to CN III)

A

double vision

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23
Q

what is ptosis? (happens during injury to CN III)

A

droopy eyelid (weak ipsilateral levator palpebrae superioris)

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24
Q

what is mydriasis? (happens during injury to CN III)

A

pupil on affected side is dilated (pupillary dilator m is unopposed as pupillary sphincter and ciliary mm are dysfunctional)

25
Q

where are the cell bodies of CN IV located?

A

tegmentum

26
Q

CN IV innervates the ______ superior oblique m

A

contralateral

27
Q

the fibers of CN IV leave the nucleus and turn caudally in paraaqueductal gray, then arch dorsally to decussate and leave the brainstem in _____-_____ junction

A

midbrain-pons

28
Q

an injury to CN IV is more/less noticeable than an injury to CN III

A

less

29
Q

an injury to CN IV results in the patient reporting ______ when going downstair or reading

A

diplopia (double vision)

30
Q

CN that has a long intracranial course that makes is susceptible to increased intracranial pressure (palsy)

A

CN VI

31
Q

CN VI innervates the _____ lateral rectus m that abducts the eye

A

ipsilateral

32
Q

where are the cell bodies for CN VI?

A

in floor of fourth ventricle, caudal pons

33
Q

what two things are medial to the cell bodies of CN VI?

A
  • medial longitudinal fasciculus

- motor fibers of CN VII

34
Q

site where fibers of CN VII wrap around and turn to exit

A

interanl genu of VII

35
Q

CN VI nucleus and internal genu together are called what?

A

facial colliculus

36
Q

injury to CN VI NERVE will cause ____ ______ in which the affected eye deviates medially

A

medial strabismus

37
Q

injury to CN IV NUCLEUS will cause what two things?

A
  • medial strabismus (just like nerve injury)

- lateral gaze paralysis

38
Q

during injury to CN VI, the ______ eye will not abduct past mid position and the _____ eye will not adduct past mid position

A
  • ipsilateral
  • contralateral

*this is due to the fact that the nucleus contains motor neurons and internuclear neurons that ascend the medial longitudinal fasciculus

39
Q

interconects CN’s III, IV, and VI nuclei and allows for coordination of head and eye movement. (both eye work together during lateral gaze

A

medial longitudinal fasciculus

40
Q

injury to the medial longitudinal fasciculus results in what 3 things?

A
  • internuclear ophthalmoplegia (paralysis of the eye due to damage between the nuclei)
  • removal of excitatory input to ipsilateral III nucleus
  • ipsilateral eye to lesion fails to move past mid position during horizontal gaze
41
Q

the first neuron in the constriction of pupils in response to light involves an afferent limb that comprised of _____ ____ cells leading to _____ _____

A
  • retinal ganglion

- pretectal nuclei

42
Q

the second neuron in the constriction of pupils in response to light is the pathway that each pretectal nuclei is linked to both _____-______ _____

A

edinger-westphal nuclei

43
Q

the third neuron in the constriction of pupils in response to light is the preganglionic parasympathetic fibers enter CN ____ and synapse in the _____ _____

A
  • III

- Ciliary ganglion

44
Q

the fourth neuron in the constriction of pupils in response to light is the postganglionic fibers in the short ciliary nerves enter the _____ and ultimately supply the _____ m

A
  • iris

- sphincter

45
Q

at rest, the lens is flattened by tension on its _____ exerted by the _____ _____

A
  • capsule

- suspensetory ligament

46
Q

the lens bulges passively when the ______ m contracts

A

ciliary

47
Q

to view an object close up: ciliary m ____, which relaxes the lens ______ ligaments

A

suspensatory

48
Q

during accommodation, both the ______ pupillae m contracts and the ______m contracts

A
  • sphincter

- ciliary

49
Q

when the sphincter pupillae m contracts during accommodation, the decreased light goes through the _____ of the lens (which is thinner)

A

periphery

50
Q

convergence is when the visual axis of both eyes converge due to increased tone in _____ ____ mm

A

medial rectus

51
Q

where in the brain do sympathetics to the eye originate from ?

A

hypothalamus

52
Q

where do preganglionic sympathetics to the eye emerge from the spinal cord?

A

first thoracic ventral nerve

53
Q

where do the preganglionic sympathies to the eye synapse?

A

superior cervical ganglion

54
Q

eyes moving as a pair

A

conjugate movements

55
Q

type of conjugate movement that involves the eyes moving from one visual target to another in high-speed movement known as SACCADES

A

scanning

56
Q

type of conjugate movement that involves smooth pursuit where the eyes follow an area of interest across a visual field

A

tracking

57
Q

type of conjugate movement that involves a gaze held on an object of interest during head movement, known as VESTIBULO-OCULAR REFLEX

A

compensation

58
Q

type of scanning where each pulls eye to its own side

A

horizontal saccades ***** look at slide 49 to understand this stuff!!!!

Anatomy (S2)(Unit 1) (10 decks)

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