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Neuroscience > Brain Stem: Midbrain > Flashcards

Brain Stem: Midbrain Flashcards

1
Q

what are the 3 general layers of the Midbrain?

A
  1. Tectum = dorsal
  2. Tegmentum = intermediate
  3. Crus Cerebri = ventral
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2
Q

what structures are on the tectum of the Midbrain?

A

(dorsal layer)

Corpus quadrigemina = S/I colliculi

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3
Q

what is the superior colliculi responsible for?

A

visual reflex response to unexpected stimuli in visual field

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4
Q

what is the inferior colliculi responsible for?

A

auditory reflex respone

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5
Q

what is the tegmentum of the midbrain a continuation of?

A

the pontine tegmentum

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6
Q

what are the cerebral peduncles?

A

crus + tegmentum

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7
Q

what is the cerebral aqueduct?

A

connection between the 3rd and 4th ventricle

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8
Q

what are the fiber tracts within the tectum of the midbrain?

A

posterior commisure

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9
Q

what does the posterior commissure do?

A

coordinate eye movements

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10
Q

list the fiber tracts in the tegmentum at the level of the inferior colliculus

A
  1. decussation superior cerebellar peduncle
  2. medial longitudinal fasciculus
  3. lateral lemniscus
  4. medial lemniscus
  5. trigeminothalamic
  6. spinothalamic
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11
Q

what info is carried in the decussation of the superior cerebellar peduncle?

A

efferent output from cerebellum crosses here

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12
Q

what info is carried in the medial longitudinal fasciculus?

A

balance with efferent limb of balance reflex

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13
Q

what info is carried in the lateral lemniscus?

A

afferent to inferior colliculus for auditory reflex

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14
Q

list the tracts located in the tegmentum of the midbrain at the level of the superior colliculus

A
  1. medial longitudinal fasciculus
  2. medial lemniscus
  3. trigeminothalamic
  4. spinothalmic
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15
Q

what are the crus cerebri?

A

descending axons from cerebrum that form corticospinal or corticobulbar tracts

divided into 4 segments

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16
Q

tracts in the most lateral segment of the crus cerebri are coming from where?

A

descending from parietal, temporal, and occipital cortex to pontine nuclei/cerebellum

17
Q

tracts in the most medial segment of the crus cerebri are coming from where?

A

descending from frontal lobe to pontine nuclei/cerebellum

18
Q

where is the corticospinal tract located in the crus cerebri

A

lateral middle segment

19
Q

where is the corticobulbar tract located in the crus cerebri?

A

median middle segment

20
Q

what nuclei are located in the tectum of the midbrain?

A
  1. inferior colliculus (auditory reflex)
  2. superior colliculus (visual reflex)
  3. pretectal region
21
Q

what supplies the input to the inferior colliculus?

A

afferent input from:

cochlear, superior olivary, trapezoid nuclei via

lateral lemniscus

22
Q

efferent output from the inferior colliculus heads where?

A

thalamus

via brachium of inferior colliculus (tectospinal)

23
Q

what supplies the input to the superior colliculus?

24
Q

efferent output from the superior colliculus heads where?

A

cervical spine

via tectospinal for head turning, and tracking

25
where is the pretectal region located?
rostral to superior colliculus
26
what is the pretectal region responsible for?
papillary light reflex associated with CN 3
27
what nuclei are located in the tegmentum of the midbrain at the level of the inferior colliculus?
1. substantia nigra 2. periaqueductal gray 3. trochlear nerve nuclei 4. reticular formation
28
what is the substantia nigra?
part of basal ganglia motor efferent signaling
29
what is the periaqueductal gray responsible for?
autonomic regulation, emotion, and modulation of pain
30
what is the trochlear nerve nuclei CN 4 responsible for?
eye movement superior oblique muscle (down and medial)
31
what is in the reticular formation at the tegmentum of the midbrain at the level of the inferior colliculus?
raphe nuclei
32
list the nuclei that are located in the tegmentum of the midbrain at the level of the superior colliculus
1. oculomotor nerve nuclei CN 3 2. red nucleus 3. ventral tegmental area
33
what is the function for the occulomotor nerve nuclei CN 3 in the tegmentum of the midbrain?
1. somatomotor = S/M/I rectus, inferior oblique, levator palpebrae 2. autonomic motor = iris constriction, ciliary muscle for accommodation (PNS component)
34
what is the red nucleus responsible for?
motor modulation of flexor muscles via rubrospinal tract
35
what is the ventral tegmental area?
part of the basal ganglia motor modulators

Neuroscience (16 decks)

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