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Neuro > Motor Cortex > Flashcards

Motor Cortex Flashcards

1
Q

Motor cortices

A

Primary motor cortex
Supplementary motor area
Pre-supplementary motor area
Premotor area
Posterior parietal cortex

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2
Q

Brodmann areas

A

Area 4→ primary motor cortex
Area 6→ supplementary motor cortex and premotor area
Area 5→ post parietal cortex, imm. post to 1ª sens cortex
Areas 1, 2, 3 —> primary sensory cortex

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3
Q

Area 6 is composed of

A

2 motor areas:
- supplementary motor area (more dorso-medial)
- premotor area (ventrolateral).

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4
Q

1ary motor cortex is responsible for

A

Sending the motor order towards the anterior horn of the spinal cord

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5
Q

Primary motor area characteristics

A

Somatotopic distribution - represented by motor humunculus

Firing rate of each individual neuron correlates w/ muscle force exerted

Kinematic of the movement is coded in M1 by a neuronal population ___

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6
Q

Motor humunculus represents

A

Areas of precentral gyrus that control voluntary muscles in the body.

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7
Q

Sensory humunculus represents

A

Somatotopic distribution of info reaching the postcentral gyrus from different bodily parts

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8
Q

In primary motor cortex we codify

A

Simple movements corresponding to regions of the body, not single muscles

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9
Q

Direction of movement is determined by

A

A group of neurons (not a single one)

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10
Q

Vascularization of primary motor cortex

A

Lateral aspect (face and upper limb): middle cerebral art

Medial aspect (lower limb): anterior cerebral artery

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11
Q

Aneurysm in anterior cerebral artery =

A

problems that affect the leg

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12
Q

Aneurysm In the middle cerebral artery =

A

problems that affect face, eye, arms,..

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13
Q

2ary motor areas (SMA and premotor cortex) is responsible for

A

“Preparing” for movement (coordinated movements, tasks)

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14
Q

Sequence of events when we make a movement

A

1st we decide that we want to move (prefrontal cortex)

We chose what movement we want to perform (2ary motor, preparation)

Execute the response (1ary motor, execution)

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15
Q

Inputs to the cortex

A

1ary motor cortex: from 1ary somatosensory cortex (for reflex responses), cerebellum, post parietal areas & 2ary motor areas

2ary motor cortex: from basal ganglia, prefrontal cortex (bc before any preparation takes place, 1st we decide to move) & post parietal areas

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16
Q

Cortex receives input from

A

Thalamus and other cortical areas (EXCEPT olfaction, which goes directly to the cortex)

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17
Q

All projections from the cerebellum and basal ganglia go to

A

The cortex by first passing through the thalamus

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18
Q

Cerebellum helps

A

movements be precise (rojects mostly to 1ª motor cortex

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19
Q

Info from cerebellum reach the cortex by

A

Synapsing on thalamus (at VL and VPL nuclei)

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20
Q

Basal ganglia are involved in

A

Preparatory processes (inputs for the 2ary motor areas)

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21
Q

Info from cerebellum will reach basal ganglia by

A

Synapsing on the thalamus (in VPL and VA)

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22
Q

Supplementary areas participates in

A

Preparation of self-initiated movements (specially when movements comprise 2 body sides and are + complex).

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23
Q

Preparatory processes which take place in SMA give rise to

A

Slow potential, pre-movement potential which comes in as a wave.

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24
Q

Lesion to supplementary motor area

A

Akinesia = NO self-induced movements
(YES reflexes and stimulus-induced movements)

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25
Q

Premotor cortex is involved in

A

Stimulus-induced movements
Aiding control of proximal axial musculature and distal musculature precision movements

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26
Q

Premotor cortex subregions

A

Dorsal lateral: involved in delayed actions
Ventral lateral: adapts the hand to the shape of the object we are holding.

27
Q

Posterior parietal cortex is

A

The interphase between visual stimuli - motor executions

28
Q

Posterior parietal cortex is involved in

A

Stimulus-induced movements, specifically movements guided by visual info

Transforming visual information into motor responses (2ª + 1ª motor cortices —> prepare & execute them)

29
Q

Pre-SMA and motor learning projects to

A

SMA (area very relevant for motor learning)

30
Q

Once we learn a movement, we begin to use

A

SMA

31
Q

When we learn a movement we use

A

pre-SMA

32
Q

Once a movement is fully automated, after having done it several times→ we’ll be using

A

1ary motor cortex

33
Q

Mirror system is activated when

A

One performs an action, or when they see someone else perform said action

34
Q

Mirror system is involved in

A

Empathy
Imitation (learning to speak)

35
Q

Mirror system is related to an area located in

A

Broca’s area

36
Q

Motor tracts to spinal cord

A

Corticospinal tract
Rubrospinal tract
Vestibulospinal tract
Reticulospinal tract
Olivospinal tract
Tectospinal tract

37
Q

Fibers in rubrospinal tract are

A

Mostly crossed

38
Q

Tectospinal tract

A

Sup colliculus to spinal cord
Helps adjust head position, turn our head upon visual inputs, sound or other inputs

39
Q

Olivospinal tract

A

Only in cervical region

40
Q

Corticospinal tract

A

Neurons go from cortex to spinal cord, to activate ant horn motor neurons

41
Q

Corticospinal tract decussates at the level of

A

Pyramids in the medulla of the brainstem

42
Q

Pyramidal cells sypansis

A

Excitatory
Inhibitory

Corticospinal pathway act some neurons while inhibiting others —> to perform movements & reflexes correctly.

(in ant horn of spinal cord)

43
Q

Function corticospinal pathway

A

Keeps the reflex movements under control and is in charge of MOVEMENT PRECISION

44
Q

Lesion to corticospinal pathway

A

Lost of voluntary precision movements, still preserve the force of the movements.

Reflexes become heightened

45
Q

Divisions of corticospinal tract

A

Anterior corticospinal pathway (20%)
Lateral corticospinal pathway (80%)

46
Q

Pathway followed by the corticospinal tract

A

Neurons project from cortex - come together (int capsule) - begin to descend to spinal cord.
(Small part of int capsule is formed by corticonuclear pathway = projections from cortex that synapse at brainstem nuclei)

Midbrain: int capsule enters crus cerebri.

Pons: tract becomes scattered (pontocerebellar nuclei). But it all re-joins at the level of the medulla = pyramids

80% of tract decussat. at pyramids (pyramids decussation) = lat corticospinal pathway.

20% continue descending along ant corticospinal pathway —> decussate at corresponding level of spinal cord.

47
Q

1st, upper motor neuron axon forms

A

Corticospinal pathway

48
Q

2nd, lower motor neuron axon forms

A

The nerve fiber

49
Q

Strength depends on

A

2nd motor neuron

50
Q

Precision depends on

A

1st motor neuron

51
Q

Reflexes depend on

A

Lower motor neuron; the control and regulation of this reflex depend on the upper motor neuron

52
Q

Lesion the first motor neuron causes

A

Exacerbated reflexes —> clonus
Loss of precision (strength is conserved)
Increase muscle tone —> spasticity

53
Q

Lesion the 2nd (lower) motor neuron

A

Reflexes are abolished
Loss of strength —> (eventually) muscle atonía
No basal muscle tone

54
Q

Vestibulospinal tract

A

Direct projections from vestibular nuclei to axial muscles

55
Q

Vestibulospinal tract function

A

Keep balance

56
Q

Rubrospinal tract

A

Projections from the red nuclei in the midbrain to the spinal cord.

57
Q

Red nucleus receives

A

Sup cerebellar peduncle fibres from cerebellum.

58
Q

In rubrospinal tract, fibers mostly go to

A

Upper limb

59
Q

Rubrospinal tract functions

A

Helps make the necessary adjustments to do movements with our hands

60
Q

Reticulospinal tract

A

The cerebellum connects with reticular nuclei in the brainstem, and then fibres from it descend to spinal cord

61
Q

Reticulospinal tract function

A

Involved in posture control and axial muscle adjustments

62
Q

Corticonulear pathway

A

To nuclei of the brainstem (gives CN).
Also descends down int capsule —> synapses on brainstem.
Connections between cortex - nuclei in the brainstem = mostly bilateral (there are exceptions)

63
Q

Exceptions of bilateral innervation

A

Projections to XI CN = only ipsilateral

Projections to soft palate & uvula = mostly contralateral
Inferior part of the face = mostly contralateral

Glossal muscle (protrudes the tongue) is innervated
by XII CN = contralateral

64
Q

Lesions to the XII and X CN

A

Peripheral lesion: tongue (XII) deviate to SAME side, uvula (X) opposite side of lesion

Central lesion (prior to decussation, in corticonuclear tract): tongue (XII) will deviate to opposite side, uvula (X) towards side of lesion

Neuro (23 decks)

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