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ANAT 242 > L7 > Flashcards

L7 Flashcards

1
Q

what is the reticular formation composed of

A

Composed of clusters of gray matter scattered throughout

midbrain, pons and medulla

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2
Q

what is the role of the reticular formation

A

Its role is for arousal and it does this by the thalamus. (it sends its neurons to the thalamus)

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3
Q

what is the reticular formation involved in

A

habituation

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4
Q

what is habituation

A

a process in which the brain

learns to ignore repetitive, inconsequential stimuli while remaining sensitive to others

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5
Q

what is the reticular formation inhibited by

A

inhibited by sleep centres located in the hypothalamus & other brain regions

this is because when you are asleep you don’t want to be woken

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6
Q

what is the reticular formation depressed by

A

depressed by alcohol, sleep-inducing drugs &

tranquilisers

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7
Q

what would happen if you were to damage the brainstem

A

permanent unconsciousness
(irreversible coma) because this is where the reticular formation is therefore if that is damaged then you would be unable to be woken

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8
Q

what % of neurons are in the cerebellum

A

50%

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9
Q

what is the important functions of the cerebellum

A

balance and coordination

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10
Q

where is the cerebellum located

A

in the posterior cranial fossa

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11
Q

what is the dame of the 3 sections that the base of the skull is divided into

A

The base of the skull is divided into the anterior, middle and posterior cranial fissure

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12
Q

what structures is the cerebellum posterior to

A

the superior medullary velum ( the roof of the 4th ventricle)

and

the inferior medullary velum (chloride plexus)

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13
Q

what are the main structures of the cerebellum

A

cortex, white matter and deep nuclei

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14
Q

what are the primary roles of the cerebellum

A

synchronised, precisely timed movement across
multiple joints = synergistic multijoint limb movement
Eg. throwing a ball, finger-to-nose test

control of muscle tone (posture)

maintenance of balance

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15
Q

does the cerebellum give rise to conscious sensory perceptions

A

no

it receives vast amount of sensory information, but does not give rise to conscious sensory perceptions

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16
Q

is the cerebellums role for afferent or efferent information

A

it has 40x more afferents than efferents. this is because of the vast amount of sensory information coming in

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17
Q

how is synergetic multi joint movement achieved

A

Frontal motor association areas (eg. premotor cortex)
via the corticopontine-cerebellar tract, inform cerebellum of intent to start voluntary muscle contractions

At the same time, the cerebellum receives information from proprioceptors throughout the body, as well as visual
and vestibular (balance) input

The proprioceptive information includes tension in muscles and tendons and the position of joints.

This information allows the cerebellum to evaluate body
position and momentum = where the body is and where it intends to go.

The cerebellar cortex and the deep cerebellar nuclei then calculate the best way to coordinate the force of each muscle contraction to prevent overshoot, maintain posture & ensure smooth coordinated movement.

Then, the cerebellum dispatches to the motor cerebral cortex its “blueprint” for coordinating movement. The primary motor cortex then influences motor neurons in the spinal cord to produce movement.

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18
Q

what structure do the neurons from the premotor cortex go through to inform the cerebellum that you want to start a movement

A

corticopontine-cerebellar tract

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19
Q

which structures calculate the best way to ensure smooth coordinated movement

A

the cerebellar cortex and deep cerebellar nuclei

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20
Q

what would be expected if an individual had a cerebellar lesion

A

they are usually capable of
carrying out general outlines of movement, but each movement is executed with suboptimal coordination and precision.

they will be clumsy

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21
Q

what anatomy is needed to achieve synergistic multijoint movement

A

Cerebellum needs to be connected to the motor input from cerebral cortex, the various sensory inputs and needs to send its output or blueprint back to the cerebral cortex.

it also needs the cerebellar penuckle’s to connect one region of the brain to the other

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22
Q

what are the names of the 3 cerebellar peduncles and where are they located

A

the superior cerebellar peduncle is located in the midbrain

the middle cerebellar peduncle is located in the pons

the inferior cerebellar peduncle is located in the medullar

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23
Q

from what view would you see the cerebellar peduncles

A

an dorsolateral view of the brainstem

or

the anterior view of the cerebellum

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24
Q

what structures is the cerebellum posterior to

A

Brainstem, 4th Ventricle, Vela, Cerebellar Peduncles

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25
Q

when looking at the anterior view of the cerebellum what do the peduncles look like

A

they are white because they are white matter tracts

the superior on is the thin skinny bit

the middle and the inferior are the circular bit.

the middle is the circle bit closes to the superior cerebellar peduncle

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26
Q

what is a insisure

A

it is the equivalent of a sulcus in the cerebellum

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27
Q

how can you identify the anterior and posterior cerebellar incisures

A

anterior is the bit of the cerebellum that dips in where the brainstem is

posterior is the bit that dips in at the middle back of the cerebellum

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28
Q

what do the anterior and posterior cerebellar incisures contain

A

the flux cerebelli

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29
Q

what are the right and left hemispheres of the cerebellum connected by

A

the vermis

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30
Q

what are the parallel surface folds of the cerebellum called

A

folia (leaves)

31
Q

what do folia consist of

A

gray matter

32
Q

what is the white matter in the cerebellum called

A

arbor vitae

tree of life

33
Q

where do the deep nuclei sit in the cerebellum

A

in the white matter

34
Q

what are the main cells in the cerebellum

A

purkinje cell

granule cell (has parallel fibers)

mossy fibers

climbing fibers

35
Q

what plain do the dendrites of the purkinje cells sit in

A

caronal

36
Q

what are two main inputs of the cerebellar circuits

A

mossy fibers and climbing fibers

37
Q

what is the role of mossy fibers

A

mossy fibers/axons come from spinal cord or brainstem neurons and convey motor or sensory input to the cerebellum

Mossy axons form excitatory synapses with granule
neurons in the cerebellar cortex.

38
Q

what is the role of climbing fibers

A

mainly from inferior olivary nucleus therefore they bring proprioceptive input.

One ION neuron innovates 1 PC therefore this is a very precise system

Climbing axons form excitatory synapses directly with the purkinje neurons/cells in the cerebellar cortex.

39
Q

mossy fibers synapse with granule neurons. what happens from here

A

The granule neurons send their axon as a parallel fibre (because it is parallel to the surface) to form excitatory synapses with the Purkinje neurons.

40
Q

what is the role of the purkinje cell

A

Purkinje neuron is sole output neuron of the cerebellar cortex. Is inhibitory. Works with input axons to regulate the firing frequency and amplitude of the neurons in the deep cerebellar nuclei = “blueprint” sent to motor cortex.

41
Q

what is the role of the neurons in the deep cerebellar nuclei

A

they integrate synaptic output

42
Q

what are they layers of the cerebral cortex

A

outer most to inner most

molecular layer

purkinje cells

granule cell layer

white matter

43
Q

describe what a purkinje cell looks like

A

it has an oval shaped cell body in the granule cell layer

elaborate flattened, fanlike dendrite tree (sagittal section)

44
Q

what divides the cerebellum into the anterior and posterior lobe

A

the primary fissure

45
Q

what is the name of the 3rd lobe in the cerebellum

A

flocculonodular lobe

46
Q

what is the function of the lobes in the cerebellum

A

anterior and posterior lobes = coordination of movement

flocculonodular lobe = balance

47
Q

where is the flocculonodular lobe located

A

the inferior surface, deep to the vermis

48
Q

what structures make up the flocculonodular lobe

A

the 2 flocculus and the nodulus

49
Q

what is hydrocephalus effect on the tonsils

A

If you have increased intracranial pressure (hydrocephalus) then it will push the tonsils down which puts pressure on the medulla which is where the neurons for the heart and lungs are which means that if they are damaged then you will die

50
Q

what are the sagittal functional subdivisions of the superior surface of the cerebellum

A

the lateral zone (the lost lateral part)

the intermediate zone (middle)

the median zone (vermis)

51
Q

what are the 4 deep cerebellar nuclei

A

Fastigial
Globose
Emboliform
Dentate

52
Q

which of the 4 deep cerebellar nuclei from the Interposed/Interpositus Nucleus

A

Globose and Emboliform

53
Q

which deep cerebellar nuclei does the vermis project to

A

the Fastigial nucleus

54
Q

which deep cerebellar nuclei does the intermediate zone project to

A

the interposed/interpositus nucleus

55
Q

which deep cerebellar nuclei does the lateral zone project to

A

the dentate nucleus

56
Q

the Flocculonodular lobe can also be called the…..

A

= Vestibulocerebellum

57
Q

what are the Cerebrocerebellar circuits responsible for

A

controls multijointed movements of limbs to create fluid and coordinated movement

58
Q

what are the Spinocerebellar intermediate zone

circuits responsible for

A

controls accuracy of movement of the limbs.

eg. precision at a joint

59
Q

what are the Spinocerebellar medial/median/vermal

zone circuit responsible for

A

Controls posture via influencing axial muscles in trunk

60
Q

what are the Vestibulocerebellar circuits responsible for

A

maintain balance via axial and limb muscles

61
Q

describe the pathway of the cerebrocerebellar circuits

A

the first thing that happens is the cerebral cortex tell the cerebellum what to do via the CPCT

This is from the premotor cortex neurons inform the cerebellum what you want to do

The neurons in the cerebrum to the pontine nuclei and then into the lateral zone of the cerebellum

The spino-olivary tract comes up form the spine, crosses in the olive and then crosses to the lateral zone. This is proprioceptive information

The PC cells then go to the deep cerebellar nuclei (dentate nucleus) which then send the blueprint back up to the motor cortex

From there the movement gets sent down

62
Q

describe the pathway of the spinocerebellar intermediate zone circuits

A

This time the CPCT goes to the intermediate zone no the lateral zone

Even though this is called spine there is still CPCT input

Sensory information comes up from the inferior olivary nucleus to the intermediate zone

The PC innovate the interpositus neurons which create the blueprint

This then gets sent through the red nucleus to the thalamus to motor cortex and leaves through the lateral corticospinal tract

63
Q

describe the pathway of the spinocerebellar vermal zone circuit

A

Integrating information from the spinocerebellar tracts and the inferior olivary nucleus

These go the the median zone of the deep cerebellar nuclei the PC cells innovate the visidual nucleus (the most medial). This goes to the thalamus and then to the PMC. It leave through the ventral corticospinal tract

64
Q

describe the pathway of the vestibulocerebellar circuits

A

Input from the inferior olivary nucleus

These are climbing and mossy fibers

The mossy fibers are coming from the vestibular labyrinth (semi-circular canals)

Both climbing and mossy fibers go via the inferior cerebellar peduncle to the pocculondualar lobe. From there the PC go directly with the vestibular nuclei to the vestibular spinal tract.

65
Q

what is the role of the inferior cerebellar peduncle

A

conveys sensory information to the cerebellum from muscle proprioceptors throughout the body
AND from the vestibular nuclei of the brainstem
(equilibrium & balance)

contains both afferent (chiefly) & efferent axons

66
Q

what is the role of the middle cerebellar peduncle

A

contains only afferent axons (crossed axons from contralateral pontine nuclei). Eg CPCT

67
Q

what are the characteristics of the superior cerebellar peduncle

A

formed by axons that arise from deep cerebellar nuclei (main efferent pathway)

fibers decussate at various levels

crossed fibers ascend - either terminate in the red
nucleus or continue rostrally to end within the
thalamus (then to cerebral motor cortex)

68
Q

what does ipsilateral haf mean

A

same side

69
Q

where does each cerebellar hemisphere excert its influence in the body

A

Each cerebellar hemisphere exerts its influence primarily on the ipsilateral half of the body

this is because they are doubly crossed

70
Q

what is ataxia

A

inaccuracy in the speed, force and distance of

movement (staggering gait, dysmetria, slurred speech)

71
Q

what is a tremor

A

involuntary oscillation of the limbs or trunk

72
Q

what is nystagmus

A

rhythmic involuntary oscillation of the eyes

73
Q

what could be the cause of a headache and vomiting in relation to the cerebellum

A

this is often 1st symptoms of cerebellar tumour

Tumor which blocks the CSF drainages from the 4th ventricle which increases the pressure causing a headache. The vomiting if from pressure on the medulla

ANAT 242 (17 decks)

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