Motor And Sensory Flashcards by Clare Cummins

What are the two main sulci of the brain?

Central sulcus

Lateral sulcus

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What the function of the limbic lobe and where is it located?

Involved in emotion and memory

Located in medial surface of cerebral hemisphere

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What is the function of the insula and where is it located?

Function: emotion and primative senses like smell
Located: floor of the lateral fissure

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Which part of the brain is key for fine tuning of movement

Cerebellum

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What does the corpus callosum do?

Connects the two hemispheres

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What does grey matter consist of?

Neuronal cell bodies

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What does white matter consist of?

Axons

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What is the purpose of the thalmus?

Important relay station for cognitive, sensory and mainly motor systems

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What is the basal ganglia important for?

Fine tuning of movement

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What is the function of projection fibres?

Connects the cerebral cortex to structures lower down in the nervous system

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What is the function of association fibres?

connects areas of the cortex within the same hemisphere

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What is the function of commissural fibres?

thick white matter tract connecting the two cerebral hemis

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What is the corpus callosum?

white matter commissural fibres - connecting the two hemis

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What is the corona radiate?

bulk of hemispheric white matter (inc. projection, association and commissural fibres) - lesion here wouldn’t be so bad as everything is spread out

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What is the internal capsule?

Projection fibres coming down and out of the brain (or into it)

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What is the cerebral peduncle?

exit/entry point where lots of white matter are closely packed together. Small lesion here would have a big effect

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What do the premotor cortex and supplimentary motor cortex assist in?

The preparation and initiation of movement

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What Broadman area is the frontal lobe?

B6 (contains premotor and supplimentary cortex)

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What braodmans area is the primary motor cortex

B4 (where the pyramidal system originates)

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What is a pyramidal neuron?

An UMN originating in primary motor cortex

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How is primary motor cortex organised?

Somatotopically (according to body geography). The amount of primary motor cortex and pyramidal neurons associated with a body part is proportional to the degree of fine motor control required of that body part

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Direct motor control pathway =

pyramidal system/ cortiospinal path (i.e. from the cortex down the spine)

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Primary motor cortex controls movement on which side?

The opposite side

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The cortiospinal tract decends on the same side of the nervous system until the…

lower medulla

After cross at the level of the lower medulla, the UMN axons continue to travel down the spinal cord as the...

lateral cortiospinal tract

would a lesion of the internal capsule be big or small

very big. Pyramidal fibres from the leg, arm and face are all really close together at this point so a lesion here would result in damage to all those muscles.

Would a lesion of the corona radiate be big or small

small as the fibres as all so spread out

Where do UMN synapse with LMN

in the anterior horn of the spinal grey matter (which is on the inside - opposite to the brain)

What is the cortiobulbar tract?

It is the part of the cortiospinal tract which contains the UMN that control the bulbar muscles (i.e. cranial nerves 7-12). It is located within the medial part of the cortiospinal tract

Where do UMN of the cortiobulbar terminate?

In the lower cranial nerve motor nuclei (tends not to be in the medulla but in the midbrain or brainstem )

Which two cranial nerves do NOT recieve bilateral innervation?

7 and 12 (lower facial and tongue)

Where do LMN exit the spinal cord?

in the anterior spinal nerve root

Which is worse; damage to a spinal root or damage to a peripheral nerve

spinal root - affects lot of muscles

What happens when muscle tone is too high?

Stretch receptors are activated, which send a message to inhibitory interneurons which send signals to the LMN to dampen down the effects. UMN are synapsing on the these inhibitory interneurons and therefore are very important in controlling tone.

In terms of tone, UMN lesions result in...

increased tone (decreased activation of inhibitory interneurons -> reduced inhibitory effects on LMN -> LMN activity increased -> increased muscle contraction -> increased muscle tone

In terms of tone, LMN lesions result in...

decreased muscle tone (floppy)

spinal motor circuts responsible for tone are also responsible for...

reflexes (therefore testing these is a good way of testing the integrity of the spinal network)

What happens in a LMN lesion?

transmission of action potentials to muscle fibres is reduced or absent, so muscle contraction is reduced or absent

What causes a LMN pattern deficits?

Lesions of the spinal grey matter, spinal nerves or peripheral nerves

What are the patterns of LMN Lesion?

``` muscle weakness decreased tone (flaccidity) decreased tendon reflex responses (hyporeflexia) Less of muscle mass (wasting) Some disorders - fasciculations ```

What are UMN lesions caused by?

Damage to Motor Cortex or Pyramidal tract

What are the patterns of a UMN lesion?

increased muscle tone (spasticity) increased reflex response (hyperreflexia) preservation of muscle mass no fasciculations

Which systems support the fine tuning of movements?

The extrapyramidal system and cerebellar systems

What is the important neurotransmitter of the extrapyramidal system?

Dopamine

An imbalance in the extrapyramidal system causes what kinds of disorders?

2 kinds of movement disorders: 1. Hyperkinetic (Cerebral Palsy, Huntington) 2. Hypokinetic (e.g. Parkinsons)

Cerebeller hemis control movement on which side?

Same side of the body

How would you examine someone's muscle function?

Look at them - their posture, symmetry, any involuntary movements or clear signs of atrophy Then test: tone, power, reflexes, coordination and gail

What is muscle tone

Resistance to passive movement

What is muscle power?

Resistance to active movement

What happens in an abnormal babinski response

Big toe curls up - sign of UMN lesion

Effect of pyramidal tract lesion?

Affects most of the muscles on one side of the body

Effect of peripheral nervous system lesion?

Affects a small subset of muscles

Effect of muscle disorder?

Tends to affect large muscles

What is hemiparetic posture?

Where flexor (bending) muscles are stronger than extensor muscles in the upper limb and the opposite is true in the lower limb

What is monoplegia

Paralysis of one limb

Key signs of Myasthenia Gravis?

Fatigability | often affecting muscles we use a lot - e.g. eyelids

How would you examine co-ordination?

Finger nose test | Heel shin test

Signs of Cerebellar Dysfunction

``` DANISH Dysdiadochokinesis - bas successive movements Ataxia Nystagmus (involuntary eye movements) intention tremor Slurred speech Heel shin ataxia ```

What are the two sensory pathways?

Dorsal pathway | Spinothalamic Pathway