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Medsci 142 > 01 Nervous > Flashcards

01 Nervous Flashcards

1
Q

What division does the spinolateral tract belong to (lateral spinothalamic)

A

Somatosensory, non-discriminatory, pain and temperature, periphery to the brain

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2
Q

What division does the dorsal column medial lemniscus belong to ?

A

Somatosensory, discriminatory, touch and pressure, skin to brain

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3
Q

What division does the pyramidal tract/ corticospinal tract belong to ?

A

Motor information from the brain to periphery

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4
Q

How many regions is the brain divided into and state these regions

A
  • 3 - Forebrain, Midbrain and Hindbrain
  • cerebrum, cerebellum, brainstem
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5
Q

What is the cerebral cortex and what is its function?

A

The cerebral cortex is the outermost layer of the brain and is responsible for high functional activities (language, thought, reading)

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6
Q

What are the four lobes of the brain?

A

Frontal, parietal, occipital, temporal

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7
Q

Where are the motor and sensory cortical homunculus found respectively?

A
  • motor - precentral gyrus
  • sensory - postcentral gyrus
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8
Q

What is the left hemisphere of the brain responsible for?

A

verbal language production and processing

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9
Q

What is the right hemisphere of the brain responsible for and what are its functions specifically?

A
  • majority of non-dominant processing
  • non-verbal language, emotional expression, spatial skills, conceptual understanding, artistic and music skills
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10
Q

State the functions of the Frontal association cortex

A

personality, behaviour, memory, intelligence, cognitive function

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11
Q

State the functions of the parietal association cortex

A

spatial skills, 3D recognition

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12
Q

State the functions of the temporal association complex

A

memory, aggression, mood, intelligence

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13
Q

What is the function of the corpus callosum?

A

communication between the two hemispheres of the brain

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14
Q

What is the function of the cingulate gyrus?

A

part of the limbic system, processing emotions and behavior regulation

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15
Q

Where is the primary visual cortex?

A

occipital lobe

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16
Q

What is a gyrus?

A

ridge in the brain

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17
Q

What is a sulcus?

A

a groove

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18
Q

Which functional activity would mostly likely be affected if someone suffered from a stroke?

A

ability to speak and comprehend speech

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19
Q

Name the three types of aphasias and what they consist of

A
  • motor aphasia or non fluent aphasia - can understand but cant speak
  • connectional aphasia - can understand and speak but their response is inappropriate
  • sensory or fluent aphasia - cannot understand but can speak
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20
Q

State which areas of the brain are affected in each different type of aphasia

A
  • wernicke’s area - sensory/fluent aphasia
  • broccas area - motor/non-fluent aphasia
  • arcuate fasiculus - connectional aphasia
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21
Q

What hemisphere of the brain are the 1 motor and sensory cortex?

A

Both

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22
Q

Name the three protective layers of the CNS

A
  • vertebrae of the spinal column and skull
  • meninges (pia, arachnoid, dura mater)
  • cerebrospinal fluid
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23
Q

State the number of vertebrae and their classification

A

8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal

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24
Q

What passes through the ventral root of the spinal cord?

A
  • motor fibres of the spinal nerve
  • efferent neurons
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25
Q

What passes through the dorsal root of the spinal cord?

A
  • sensory fibres of the spinal nerves
  • afferent neurons
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26
Q

Explain the difference between efferent and afferent neurons

A
  • efferent - away from the spinal cord and to the peripheral nervous system
  • afferent - to the spinal cord and carries sensory information from receptors to the CNS
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27
Q

How is pain and temperature information conducted to the brain, describe these neurons

A
  • free nerve endings
  • unmyelinated
  • conduct 1 m/s
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28
Q

Explain what a corpuscle is and how nerve information is conducted to the CNS

A

a corpuscle encases the nerve ending under the skin. the nerve is myelinated and responds to touch and pressure.
the nerves can conduct 50 m/s to the CNS

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29
Q

Name the two types of Corpuscles and what their function is

A
  • Meissners - responds to touch
  • Pacinian - repsonds to pressure
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30
Q

Where can opiod receptors be found on the nerve?

A

nerves that are responsible for pain

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31
Q

What are the two major somatosensory pathways from the skin to the cerebral cortex?

A
  • discriminatory - touch and pressure - dorsal column medial lemniscus pathway
  • Non-discriminatory - pain and temperaturse - lateral spinothalamic tract
32
Q

Explain the option a sensory neuron has once it reaches the spinal cord in the dorsal column -medial lemniscus pathway

A
  • the peripheral receptors that are encapsulated send a nerve impulse that goes the spinal cord. Neuron 1 enters the spinal cord through the dorsal root, where its cell body is located in the dorsal root ganglion.
  • neuron 1can now go 3 ways
  1. To the gracile or cuneate fasiculus(depending on where the sensory information came from)
  2. It synapses onto neuron 2 in area 3 + 4 and back to the cuneate or gracile fasiculus that sends information out and up into the spinal cord or
  3. It goes to the lower motor neuron pool where is synapses with a lower motor neuron that exits the ventral root and generates a myotactic reflex (information does not go to the brain)
33
Q

Explain the continuation of the pathway when neuron 1 in the dorsal column medial lemniscus pathways goes via the cuneate or gracile fasiculus

A
  • neuron 1 synapses onto neuron 2 in the lower medulla where it decussates via the internal arcuate fibres to the medial lemniscus in pons
  • neuron 2 then extends from the lower medulla to the thalamus
  • neuron 2 synapses onto neuron 3 in the thalamus, neuron 3 then travels through the internal capsule to the primary somatosensory cortex
34
Q

Explain the function of the thalamus

A

the thalamus determines how much excitatory information the brain needs to learn about given everything else thats going on out in the world

35
Q

Describe the pathway a free ending nerve takes when it reaches the spinal cord from the periphery (spinothalamic tract)

A
  • neuron 1 enters the dorsal root and
    enters the grey matter via lissauers tract
  • it then decussates in region 1+2,
  • it decussates in the anterior white commissure and synapses to neuron 2
  • neuron 2 enters the ventral funiculus which carries the information up the spinal cord
  • neuron 2 extends from the spinal cord to the thalamus
  • in the thalamus, neuron 2 synapses onto neuron 3 which passes through the internal capsule to the primary somatosensory cortex
36
Q

What do the spinothalamic tract and the dorsal column medial lemnsicus pathway have in common

A
  • three neurons
  • both come together in the thalamus
37
Q

Where would sensory loss occur if there is a lesion on the right side in the brain/brainstem?

A
  • loss of discriminative sensation on the left (because neruons have already decussated)
  • loss of pain and temperature sensation on the left (because neruons have already decussated)
38
Q

Where would sensory loss in the spinothalamic and dorsal column medial lemnsicus pathways occur of there is a lesion on the right side in the spinal cord?

A
  • DCMLP - loss of discriminative sensation on the right because nerves only decussate in lower medulla and this is a pathway on both sides, so we would lose sensory on the same side of the lesion since the nerves only decussate in the lower medulla
  • SPINOTHALAMIC - loss of pain and temperature on the left (nerves have decussated already in the spinal cord)
39
Q

A lesion in the brain/brainstem is knows as _______ sensory loss

A

associative

40
Q

A lesion in the spinal cord is knows as _______ sensory loss

A

dissociative

41
Q

Name the two areas of the fore brain that are responsible for initiating and executing smooth movement control and explain how they work together

A
  • pre-motor cortex and the 1° motor cortex
  • pre-motor cortex is the planning part of the brain and decides what neurons need to be activated the bring about smooth muscle control.
  • the 1° motor cortex is the final pathway that brings about movement control
  • the pathway connecting the two is the basial ganglia system
42
Q

What types of neurons can be found in the cerebral cortex that are responsible for motor function?

A
  • Betz or pyramidal neruons
  • largest neurons in the body, up to 160 micrometers and 1.2 metres long (extend to the spinal cord)
43
Q

Why is the face so large in the homunculus representation on the 1° motor cortex?

A

this indicates that there are millions of neruons in the face that can be acitvated

larger representation is an indication of the magnitude of neruons/control we have over that area of the body

44
Q

What is the function of the pyramidal tract?

A
  • initiating, controlling and stopping movement
45
Q

Why do some parts of the body have a larger representation in the 1° motor cortex than others?

A

because there needs to be finer control of the muscles innervated in that area

46
Q

What is the name of the system that is the main motor tract in the brain and brings about movement in the periphery?

A

corticospinal tract / pyramidal tract

47
Q

Describe the pathway of motor information beings sent from the cerebral cortex to skeletal muscle

A
  1. pyramidal neuron in the 1° motor cortext that passes through the internal capsule, down through the midbrain, pons and medulla
  2. At the level of the lower medulla, about 85% of the neurons decussate and enter the motor columns in the spinal cord.15% of the neurons remain on the same side
  3. At the motor columns, the pyramidal neurons synapse into area 8 + 9, the lower motor neruron pool. (this is where the UMN terminate) (it is at the spinal segemental level where the 15% remaining neurons decussate and enter the lowe motor neuron pool)
  4. The LMN then exit ventrally and innervate the muscle in the periphery
48
Q

Name the tract that the 85% of neurons that decussate, take. and the pathway that the remaining 15% take.

A
  • 85% - lateral corticospinal tract
  • 15% - ventral corticospinal tract
49
Q

Is motor information carried anteriorly/ventral or posteriorly/dorsal and what about sensory?

A
  • anteriorly/ventral - motor
  • posteriorly/dorsal - sensory
50
Q

What is the internal capsule?

A

bundle of white matter allowing information to go up into the cortex or down from the cortex

51
Q

Where do the neurons coming from the cerebral cortex decussate?

A

at the lower medulla and and the spinal segmental level

52
Q

What area of the brain does a lesion of the UMN occur?

A

pons

53
Q

What effect does a lesion on the UMN have on LMN?

A
  • taking away UMN control on the LMN results in the LMN carrying out their normal functions but without control from the top
54
Q

What affect does loss of LMN control have on the human body and explain the biological mechanism behind this? (UMN lesion)

A
  • Spastic paralysis
  • LMN are normally under reflex control
  • if you leave a reflex to happen without controlling it from the cortex, you end up with the reflex reinforcing itself.

i.e you get stiffness and rigidity and the inability to relax muscles as they are now under the control of the reflex arc, not the UMN

55
Q

What area of the brain does a lesion of the LMN occur?

A

spinal cord damage

56
Q

What effect does a lesion of the LMN have on the human body and explain the biological mechanism behind this?

A
  • Flaccid paralysis
  • there is no LMN control and thus the LMN is not innervating the muscle, resulting in flaccid, limpness
57
Q

What are the symptoms of flaccid paralysis?

A
  • no nervous control of muscle at all
  • decreased muscle activation and therefore less/decreased tone
58
Q

What are the symptoms of spastic paralysis?

A
  • jerky movements
  • increased muscle activation and therefore more/increased tone
59
Q

State four functions of the cerebellum in relation to movement

A
  • Direct output to spinal cord
  • maintains balance
  • coordinates, maps, terminates movement
  • works with unconscious movement eg. swinging of arms
  • adjusts movements to account for discrepancy between planned and actual movements
60
Q

State four functions of the basal ganglia in relation to movement

A
  • no direct input/output to spinal cord
    • conveying mood through movement
    • initiation of movement
    • modifies movement after practice to be smoother, more controlled and precise
61
Q

Define the term Tremor, bradykinesia and hypokinease and explain why patients with Parkinsons disease display these symptoms

A
  • tremor: rhythmic shaking movement
  • Bradykinesia: slowness of movement
  • hypokinesia: when movements are not wide ranging
62
Q

What are the characteristic motor symptoms of Parkinson’s disease?

A
  • bradykinesia/hypokinesia
  • rigidity
  • tremor at rest
63
Q

Describe the overall structure and function of the pyramidal tract and explain how it contributes to muscle control

A

The pyramidal tract extends from the primary motor cortex down the spinal cord, through the motor column and to the skeletal muscle

system that controls voluntary muscle control.

The pathway begins in the pre motor cortex where an upper motor neuron will go through the basal ganglia line system, back to the cerebral cortex and then commence via the pyramidal tract.

The pyramidal neurons start in the primary motor cortex, go through the internal capsule, down the ponds and medulla where 85% of the neurons with decussate to the other side and go via the lateral corticospinal tract.

The remaining 15% of neurons will remain on the same side and go down the anterior corticospinal tract.

The upper motor neurons from both pathways terminate in the motor columns where they will synapse to the lower motor neurons in the lower motor neuron pool located in the ventral horn. From here the lower motor neurons will innervate skeletal muscle.

64
Q

Draw the neurons involved in the basal ganglia circuitry and indicate what neurotransmitter is used in each

A

refer to notes

65
Q

What happens when something goes wrong with the basal ganglia in terms of movement?

A
  • difficulty initiating movement
  • voluntary movements will be coarse/unrefined due to the loss of smoothing muscle movement
66
Q

What happens when something goes wrong with the cerebellum in terms of movement?

A
  • difficulty stopping movement
  • loss of normalisation of actual movement to align with planned movement
  • difficulty mapping and coordinating movement
  • loss of balance, loss of unconscious movement (posture)
67
Q

If there is a lesion in the right side of the cerebellum which side of the body is affected?

A

right side (the cerebellum controls the same side of the body)

68
Q

If there is a lesion in the right side of the basal ganglia which side of the body is affected?

A

left side

69
Q

Which neurons are affected in people with Parkinsons?

A

60 - 80% of dopamine producing neruons are gone

70
Q

Explain in terms of neurons and their neurotransmitters in the basal ganglia circuit how neurons are affected in people with Parkinsons?

A
  • Neuron from the pre motor cortex that uses glutamate is excitatory goes to the striatum
  • A neuron from the substantia nigra (inhibitory or exitatory) synapses onto the 3 different types of neruons and uses dopamine
  • 3 Neurons in striatum are GABBA inhibitory neurons and are primed by the dopamine to fire when there is drop of glutamate from the neruon from the pre motor cortex.
  • they synapse onto a neuron that goes to the VA-VL part of the thalamus (also GABBA urgic) which then extend to the cerebral cortex and synapses onto an UMN
  • In people with parkinson’s, 60-80% of the dopamine producing neurons are gone and thus not being able to activate the neurons in the striatum. (the addition of glutamate wont make a difference as there is no dopamine to prime them).

-If you remove the inhibition from neurons that are usually inhibitory , leaving those neurons to fire as much as they like. Increasing inhibiton on the excitatory neurons (in thalamus up to cerebral cortex) you end up with hypoexcitability in the upper motor neurons which leads to hypoactivitiy in the muscle.

71
Q

Explain the effects of levodopa on people with parkinsons

A
  • precursor to dopamine
  • levodopa increases dopamine levels, but too much dopamine can cause depression, psychosis and excessive rewards.
  • when dopamine levels drop again, people experience stiffness and rigidity.
  • (people with schizophrenia often stop taking their meds because it lowers their dopamine levels and they get stiffness and rigidity)
72
Q

What is the primary visual cortex responsible for, and what is the secondary visual cortex responsible for?

A

primary - receives vision from visual field, no interpretation
secondary - interpretation of vision

73
Q

Gracile and Cuneate relate to which areas of the body?

A

Gracile - Lower limbs
Cuneate - Upper limbs

74
Q

What other treatments besides levodopa do Parkinsons patients have?

A

pallidotomy
thalamotomy
deep brain stimulation

75
Q

What are novel treatments for Parkinsons?

A

cell transplantation, gene therapy

Medsci 142 (10 decks)

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