CNS Unit 10 Eye movements and Brainstem pt. 3 Flashcards

1
Q

What muscles does the Oculomotor Nerve Innervate?

CN 3

A
  • Levator Palpebae
  • Superior Rectus
  • Inferior Rectus
  • Middle Rectus
  • Inferior Oblique
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2
Q

The oculomotor nerve has a parasympathetic function. What is the name of the Accessory Parasympathetic Nucleus?

What is this for?

A

Edinger-Westphal Nucleus

This is for Pupil Constriction

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3
Q

What is the difference between Direct Response and Consensual (Indirect) Response in terms of pupil constriction?

A

If light is shined on the Right eye and the Right eye constricts, this is called Direct Response. On the opposite eye its called the Consensual (Indirect) Response.

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4
Q

What is the Accommodation-Convergence Reflex in the eye?

A

This is when there is a change in shape of the lens and constriction of pupil, while the eyes move in to focus on the near object

Example: Holding a pen in front of your face and looking at the wall then switching to looking at the pen.

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5
Q

What would happen if CN 3 were damaged?

A
  • The eye would deviate laterally
  • The pt would have Diplopia (Blurred Vision)
  • The pt would have Ptosis (Drooping eyelid)
  • The pupil will not constrict (But this wont affect the contralateral side)

Both the Pupilary and Accommodation-convervence reflex will be affected on the ipsilateral side

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6
Q

What is the function of the Trochlear Nerve?

CN 4

A

Motor to Superior Oblique

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7
Q

Where is the nucleus for the Trochlear Nerve found?

A

Found in the Periaqueductal Gray at the level of Inferior Colliculus

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8
Q

How does the Trochlear Nerve leave to get to the Superior Oblique muscle?

A

Leaves posterior and wraps around to the ventral side of cerebral peduncle into cavernous sinus area then into Superior Orbital Fissue then to the Superior Oblique muscle

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9
Q

What would happen if the Trochlear Nerve were damaged?

A
  • There would be difficulty moving the eye down and laterally
  • There may be a vertical/medial strabisums or vertical diplopia
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10
Q

What is the Function of the Abducens Nerve?

CN 6

A

Motor to Lateral Rectus

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11
Q

Where is the nucleus for Abducens Nerve found?

A

The nuclei is found in the pons below the floor of the 4th ventricle near the Facial Colliculus

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12
Q

How does the Abducens exit to get to the Lateral Rectus?

A

Exits at Pontomedullary Junction and travels through cavernous sinus area and then through the Superior Orbital Fissue to the Lateral Rectus

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13
Q

What would happen if the Abducens Nerve were to be damaged?

A
  • There would be difficulty turning the eye outward (laterally)
  • Leads to medial strabismus or diplopia
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14
Q

What test is very good at testing the different CN of they eye along with the muscles?

A

The “H” Test

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15
Q

When the Eye is Abducted, what does the Superior Rectus act as?

A

The Superior Rectus acts as a Pure Elevator when the eye is abducted

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16
Q

When the eye is Abducted, what does the Inferior Rectus act as?

A

The Inferior Rectus acts as a Pure Depressor when the eye is abducted

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17
Q

When the eye is Adducted, what does the Superior Oblique act as?

A

The Superior Oblique acts as a Pure Depressor when the eye is adducted

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18
Q

When the eye is Adducted, what does the Inferior Oblique act as?

A

The Inferior Oblique acts as a Pure Elevator when the eye is adducted

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19
Q

What are the Main Components of the Brainstem?

A
  • Cranial Nerves
  • Long Tracts (Motor and Sensory Pathways)
  • Reticular Formation (The core of the brainstem)
  • Cerebellum
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20
Q

On the Ventral side, what CN is associated with the Midbrain?

A

Oculomotor Nerve

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21
Q

On the Dorsal side, what CN is associated with the Midbrain?

A

Trochlear Nerve

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22
Q

What are the 3 main areas of the Midbrain?

A

Tectum, Tegmentum, and Basis

The hole is the Cerebral Aqueduct

  • The Tectum is the “roof”, its a cut of either the superior or inferior colliculi
  • The Tegmentum makes the bulk of the midbrain, here you find the red nucleus
  • The Basis is the most ventral portion, this is where we have a large collectionof fibers for the corticobulbar and corticospinal tracts
    (Corticobulbar pathways carrying info from the cortex to brainstem;
    Corticospinal is info carried from cortex to spinal cord-motor info)
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23
Q

What are the Myelin-Stained sections of the Midbrain at the level of the Superior Colliculi?

A
  • Edinger-Westphal Nucleus (CN 3)
  • Oculomotor Nucleus
  • Mesencephalic Trigeminal Nucleus (CN 5)
  • Red Nucleus
Starred are important
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24
Q

What are the Myelin-Stained sections of the Midbrain at the level of the Inferior Colliculi?

A
  • Trochlear Nucleus
  • Fascicles of Trochlear nerve
  • Superior Cerebellar Peduncle and Decussation
Dont confuse Superior Cerebellar Peduncle and Decussation and Red Nucleus
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25
Q

In the Midbrain what is the function of th Periaqueductal Gray?

A

Pain Modulation

Associated with the Spinothalamic Tract

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26
Q

On the Ventral side, what CN is associated with the Pons?

A
  • Trigeminal (V)
  • Abducens (VI)
  • Facial (VII)
  • Vestibulocochlear (VIII)
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27
Q

On the Dorsal side, what structures are associated with the Pons?

A
  • Facial Colliculus
  • Cerebellar Peduncles: Superior, Middle, Inferior
  • Fourth Ventrical
28
Q

On the Ventral side, what CN is associated with the Medulla?

A
  • Glossopharyngeal
  • Vagus
  • Spinal Accessory
  • Hypoglossal
29
Q

What are the Myelin-Stained sections of the Open Medulla?

A
  • Inferior Olvary Nucleus: Dorsal Accessory, Principal, Medial Accessory
  • Vestibular Nuclei
  • Solitary Nucleus (CN VII, IX, X)
  • Dorsal Motor Nucleus of Vagus (CN X)
  • Hypoglossal Nucleus ( CN XII)
  • Spinal Trigeminal Nucleus (CN V, VII, IX, X)
  • Nucleus Ambiguus (CN IX, X, XI)
30
Q

What are the Myelin-Stained sections of the Closed Medulla?

A
  • Cuneate Nucleus
  • Gracile Nucleus
  • Medial Lemniscus and Sensory Decussation
31
Q

What is the Function of the Rostral Reticular Formation?

A

This merges with the subglobttic region and lateral Hypothalamus

  • This communicates with the subthalamic area
  • This deals with alertness and states of consciousness as well as Arousal
32
Q

What is the Function of the Caudal Reticular Formation?

A

This merges with the spinal cord

  • This works with the Cranial Nerve nulei and spinal cord, to carry out reflexes, motor and autonomic functions
33
Q

What are the cortical areas that are associated with the Rostral Reticular Formation?

A
  • Medial/Lateral Parietal Association Cortex: This deals with communication of the rostral portion of arousal circuits, these arousal ciruits also reside in the upper brainstem and diencephalon
34
Q

What are the Levels of Consciousness?

The 3 A’s

A
  • Alertness: Brainstem and arousal circuits
  • Attention: Additional processing in frontoparietal association cortex
  • Awareness: Subjective and personal experience
35
Q

What are the 5 Subcortical Arousal Systems?

A
  • Upper Brainstem Neurons
  • Upper Brainstem neurons and pntomesencephalic reticular formation neurons
  • Posterior hypothalamic neurons
  • Basal Forebrain Neurons
  • Neurons in the Rostral thalamic intralaminar nuclei and medial thalamic nuclei
36
Q

Subcotical Arousal Systems

What do the Upper Brainstem Neurons release? Where do they project?

A

The typically release the neurotransmitter Norepinephrine, Serotonin, and Dopamine

  • They project to cortical and subcortical forebrain

“How the system wakes up”

37
Q

Subcortical Arousal Systems

What do the Upper Brainstem Neurons and Pontomesencephalic Reticular Formation Neurons Release? Where do they project?

A

Release Acetylcholine and Glutamate

  • They project to the thalamus, hypothalamus and basal forebrain
38
Q

Subcortical Arousal Systems

What do the Posterior Hypothalamic Neurons release? Where do they project?

A

Release Histamine and Orexin

  • They project to cortical and subcortical targets
39
Q

Subcortical Arousal Systems

What do the Basal Forebrain Neurons release? Where do they project?

A

Typically release Acetylcholine

  • It projects to the cerebral cortex
40
Q

Subcortical Arousal Systems

What do the Neurons in the Rostral Thalamic Intralaminar Nuclei and Medial Thalamic Nuclei release? Where do they project?

A

Release Glutamate

  • Projects to the Cerebral cortex
41
Q

How may a patient present if they have damage in the Upper Brainstem Ponsomesencephalic reticular formation?

A

The patient may be in a coma

42
Q

What are the Major Inputs to the Pontomesencephalic Reticular Formation?

A
  • Thalamic reticular nucleus
  • Limbic and Cingulate Cortex (Deals a lot with emotion)
  • Frontoparietal Association Cortex
  • Sensory inputs coming from peripherary
43
Q

Where are the locations of cell bodies of Norepinephrine?

A

Pons: Locus ceruleus and lateral tegmental area

44
Q

What is the Main Target for Norepinepherine?

A

The Entire CNS

45
Q

What is the Function of Norepinephrine?

A

Alertness, and mood elevation

Important for sleep wake cycle

46
Q

Where is the location of the cell bodies of Dopanine?

A

Midbrain: Substantia nigra par compacta and ventral tegmental area

47
Q

What are the Main targets for Dopamine?

A

Striatum, Limbic Cortex, Amygdala, Nulceus Accumbens and Prefrontal Cortex

48
Q

What is the Function of Dopamine?

A

Movement initiative and working memory

49
Q

Where is the location of cell bodies of Serotonin?

A

Midbrain, Pons, and Medulla: Raphe Nuclei

50
Q

What is the Main Target for Serotonin?

A

Entire CNS

51
Q

What is the Function of Serotonin?

A

Alertness, Mood elevation, breathing control

52
Q

Where is the location of cell bodies for Acetycholine?

2 areas

A
  • Basal Forebrain: Nucleus Basalis, medial septal nucleus, and nucleus of diagonal band
  • Pontomesencephalic Region: Pedunculoponine nucleus and laterodorsal tegmental nucleus
53
Q

What are the Main Targets for Acetycholine?

Consider that theres 2 locations for this

A

If in Basal Forebrain: Cerbral Cortex including Hippocampus

If in Pontomesencephalic Region: Thalamus, Cerebellum, Pons, Medulla

54
Q

What is the Function of Acetycholine?

A

Alertness and Memory

55
Q

What are the 5 stages of the Sleep Wake Cycle?

A
  • Stages 1-4: Progressively deeper nonREM (non-rapid eye movement)
    -Controlled by sertonergic neurons of the Raphe Nuclei
  • Stage 5: REM (rapid eye movement)
    -Controlled by nonadrenergic neurons in the locus cereleus
    -Deep sleep
    -Dreaming
    -Easy to awaken
    -Paradoxial sleep: deeper than stage 4 but also resembles the awake state (muscle tone lower, EEG shows lower-voltage mixture of fast activity)
56
Q

What is the Function of the Caudal Reticular Formation?

A
  • Motor
  • Reflex
  • Autonomic Function (Respiration, Circulatory Control)
57
Q

In the Caudal Reticular Formation, what nucleus controls Respiration and circulatory control?

A

The Nucleus Soltarius (Cardiorespiratory Nucleus) in the Medulla

58
Q

Caudal Reticular Formation

What controls Respiratory Rhythm under automatic control?

A

Medulla Circuits

59
Q

Caudal Reticular Formation

What controls Respiratory Rhythm under Voluntary control?

A

The Forebrain

This is when we hold our breath, or change the rhythm of our breathing

60
Q

What artery supplies the Orange Portion?

A

PCA

61
Q

What artery supplies the Dark Purple Portion?

A

Basilar Artery (Para-median branches)

62
Q

What artery supplies the Light Purple Portion?

A

The Basilar Artery (Circumferential Branches, or the Lateral Pontine Arteries)

63
Q

What artery supplies the Green Portion?

A

SCA

64
Q

What artery supplies the Dark Blue Portion?

A

AICA

65
Q

What artery supplies the Light Blue Portion?

A

PICA

66
Q

What atery supplies the Pink Portion?

A

Vertebral Artery (Lateral Branches)

67
Q

What artery supplies the Red Portion?

A

Vertebral Artery (Paramedian Branches) and Anterior Spinal Artery