4.17. Suprasegmental Motor control Flashcards

1
Q

basic pathway of segmental control (starting from motor areas in the brain to the muscle groups)

axial muscles innervated by __ (ventromedial/dorsolateral) neurons

limb muscles innervated by __ (ventromedial/dorsolateral) neurons

A

Motor cortex, premotor areas and supplementary motor areas project down to the spinal cord (specifically either directly to the lower motor neurons in the ventral horn, or they project to interneurons that then project to groups of LMNs)

Axial muscles are innervated by the ventromedial motor neurons

Limb muscles are innervated by dorsolateral motor neurons

The lateral neurons doesn’t really exist at the thoracic level (obviously there’s no need for them); they only exist in the cervical and lumbar spine

**that little green interneuron circled in red projects to limb muscles and innervates multiple segments**

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2
Q

3 types of motor skills in clinical medicine (plus examples of each)

A

Gross motor skills: walking, running, etc (so basically things that involve using major muscle groups)

Fine motor skills: writing

Visuo-motor skills: e.g. using blocks to build things (constructing; higher order functions compared to fine motor skills)

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3
Q

descending motor pathways

A

Corticospinal Tracts

Corticobulbar Tracts

Rubrospinal Tracts

Tectospinal Tracts

Vestibulospinal Tracts

Reticulospinal Tracts

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4
Q

pathways of descending motor pathways

(e.g. Corticospinal Tracts: Brain to S.C.)

A

Corticospinal Tracts: Brain to S.C.

Corticobulbar Tracts: Brain to brainstem

Rubrospinal Tracts: Red nucleus to S.C.

Tectospinal Tracts: Superior colliculus to S.C.

Vestibulospinal Tracts: Vestibular nuclei to S.C.

Reticulospinal Tracts: Reticular nuclei to S.C.

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5
Q

LMNs to the face, head and neck are located in the ___

The LMNs to your limbs are located in the ___

A

brainstem

ventral horn of the spinal cord

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6
Q

pathway of lateral corticospinal tracts

A lesion in the dorsolateral SC will cause weakness ___ (contralaterally or ipsilaterally)

A

cortex >> internal capsule >> cerebral peduncles >> basis pontis >> pyramids >> pyramidal decussation >> dorsolateral spinal cord (as lateral corticospinal tract) >> limb muscles

A lesion in the dorsolateral SC will cause weakness contralaterally

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7
Q

pathway of anterior corticospinal tracts

a lesion in the anteromedial SC will cause weakness ___ (contralaterally/ipsilaterally)

A

cortex >> internal capsule >> cerebral peduncles >> basis pontis >> pyramids >> anteromedial spinal cord (as anteromedial spinal cord) >> axial muscles

Lesion in the anteromedial spinal cord will cause weakness ipsilaterally

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8
Q

pathway of corticobulbar tracts

corticobulbar tracts control output to the ___, ___, and ___

A

These fibers start out in the cortex then go down the internal capsule (probably the genu), through the cerebral peduncles and from there, they could either continue downwards ipsilaterally or if they reach their target, they can cross at that level

face, head, neck

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9
Q

nuclei of cranial nerves __, __ and __ receive bilateral innervation

A

Nuclei of cranial nerves 5, 7 and some of 12 receive bilateral innervation

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10
Q

briefly describe the innervation of the facial nerve nucleus (differences between upper and lower face innervation)

Bell’s palsy (signs on the face; if forehead is affected or not)

what happens if you have a lesion in the motor cortex?

A

Lower face only has unilateral innervation; upper face has bilateral innervation

Bell’s palsy: LMN facial weakness; the entire face including the forehead is affected

If there’s a lesion in the motor cortex, you’ll get contralateral face weakness, but the forehead will be spared since it’s doubly innervated

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11
Q

pathway of rubrospinal tracts

if you lost innervation through the corticospinal tracts, which functions would you preserve and which ones would you lose?

A

red nucleus >> (crossing at level of origin) >> pons >> medulla (raustral >>caudal) >> lateral anterior horn of spinal cord >> flexor muscles of limbs

preserve: gross motor functions
lose: fine motor functions

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12
Q

tectospinal tract pathway

A

Superior colliculus >> (cross at level of origin) pons >> medulla >> (medial) cervical spinal cord >> axial muscles ( plus vision)

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13
Q

function of tectospinal tracts

A

reflexive head movements related to eye movements

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14
Q

vestibulospinal tract types

pathway of each

A

medial and lateral vestibulospinal tracts

Medial vestibulospinal tract descends bilaterally in the tegmentum; innervates the lower medulla and cervical spinal cord (anterior horn)

Lateral vestibulospinal tract descends unilaterally/ipsilaterally to the entire spine; innervates extensor muscles

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15
Q

reticulospinal tract pathway

function of reticulospinal tract

A

Pontine reticular formation >> medulla >> (medial) cervical spinal cord

innervation of axial muscles most likely since its medial

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16
Q

posture definition

2 components of posture

A

Posture: Position of a person’s body parts

Components:

Orientation – positioning of body parts in relation to each other

Balance – active resistance to external forces on the body

17
Q

sway (definition)

higher centers that control balance (3 of them)

A

sway: deviation of body position away from a stable equilibrium

  • Vestibular system
  • Cerebellum
  • Cerebral cortex
18
Q

locomotion definition

role of central pattern generator; where does CPG activity come from?

A

ability to move in space

(Locomotion is basically automatically regulated (central pattern generators) )

spinal cord

19
Q

motor equivalence

A

The idea that motor cortex controls the task of motor function, but the actual action is up to other parts of the body

20
Q

In the primary motor cortex (precentral gyrus), the ___ and the ___ have the most representation because they do a lot of fine motor functions

3 main brain areas involved in voluntary movement

A

In the primary motor cortex (precentral gyrus), the hand and the face have the most representation because they do a lot of fine motor functions

Premotor cortex (right in front of the primary motor cortex); supplementary motor cortex in the interhemispheric fissure; primary motor cortex

21
Q

what are the sensory areas (near the motor areas) that are also involved in voluntary movement?

A

postcentral gyrus (primary somatosensory) and posterior parietal cortex (more higher order)

22
Q

other areas involved in voluntary movement (hint: the things he was saying were extra-pyramidal)

A

Basal ganglia

Thalamus

Brainstem

Cerebellum

(pyramidal tracts and extra pyramidal system)

23
Q

The ___ lobe is important for making a sensory picture of the world

A

posterior parietal lobe

24
Q

which area of the brain is linked to the posterior parietal lobe and is involved in making multiple sensory maps? (hint: its one of the 3 motor areas)

A

pre-motor cortex

25
Q

which area of the brain is responsible for executing voluntary movement?

A

frontal lobe (premotor cortex + prefrontal cortex)

26
Q

define readiness potential

A

Readiness potential: pre-set plan of action in your brain before you execute an action

27
Q

coordination of muscle movements following the firing of motor neurons is done at the level of the ___

A

spinal cord