Nervous System - Spinal Cord Tracts & Brainstem Flashcards

1
Q

What is the General Organization of Sensory Tracts? Does a Sensory Tract Ascend or Descend?

A

(From most peripheral to most central)

  • First Order Neuron
  • Second-Order Neuron
  • Third Order Neuron
  • Ascending (towards the brain)
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2
Q

What does the First Order Neuron do in a Sensory Tract? Where is it always located?

A
Function
- Brings sensory information to the CNS (spinal cord)
- Synapses with the 2nd Order Neuron
Location
- The Dorsal Root Ganglion (DRG)
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3
Q

What does the Second Order Neuron do?

A
  • Relays information from the 1st Order Neuron to the 3rd Order Neuron
  • Deccusates (crosses the midline) to the contralateral side
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4
Q

What does the Third Order Neuron do?

A
  • Travels from the Thalamus to somatosensory (and other regions) of the Cortex
  • Relays information to the Cortex from the 2nd Order Neuron
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5
Q

What is the exception to the 3 Neuron Rule?

A
  • The Dorsal Spinocerebellar Tract
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6
Q

What is the Function of the Dorsal Column-Medial Lemniscus (DCML) Tract? is it ascending or descending?

A
  • Conveys information about Discriminative Touch (except head region) and Conscious Proprioception (except TMJ)
  • Ascending
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7
Q

How many Neurons does the Dorsal Column-Medial Lemniscus (DCML) tract go through?

A
  • 3
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8
Q

Where is the 1st Order Neuron of the Dorsal Column-Medial Lemniscus (DCML) Tract located? What does it do?

A

Location
- Cell body within the Dorsal Root Ganglia
Function
- Brings information into the spinal cord via the Dorsal Horn
- Travels up the spinal cord to the 2nd Order Neuron in the Medulla

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9
Q

Where are the axons of the 1st order neuron of the Dorsal Column-Medial Lemniscus (DCML) Tract?

A
  • Travel on the same side as the 1st order neuron entry point of the dorsal column
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10
Q

What is the difference between the information of the Upper Limb and Lower Limb regarding the Dorsal Column-Medial Lemniscus (DCML) Tract?

A

Upper Limb
- Travels within Fasciculus Cuneatus (more lateral)
Lower Limb
- Travels within the Gracile Fasciculus (more medial)

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11
Q

Where does the 1st Order Neuron synapse onto the 2nd Order Neuron in the Dorsal Column-Medial Lemniscus (DCML) tract?

A
  • Nucleus Cuneatus of Medulla

- Gracile Nucleus of Medulla

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12
Q

Where does the Dorsal Column-Medial Lemniscus (DCML) tract go after the 1st Order Neuron synapses with the 2nd Order Neuron?

A
  • Deccusates (crosses the midline), contralaterally to the point of entry
  • Ascends through the brainstem as the Medial Lemniscus towards the Thalamus to the 3rd Order Neuron
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13
Q

Where does the 2nd Order Neuron in the Dorsal Column-Medial Lemniscus (DCML) Tract synapse with the 3rd Order Neuron?

A
  • In the Thalamus
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14
Q

Where does the 3rd Order Neuron of the Dorsal Column-Medial Lemniscus (DCML) tract go? What does it do?

A

Pathway
- Projects from the Thalamus to the sensory area of the cerebral cortex
Function
- Relays information about Conscious Sensation

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15
Q

What is the Function of the Lateral Spinothalamic Tract? Is it sensory or motor? How many Neurons does it have?

A
Function
- Conveys information about Pain and Temperature from all over the body (except the head region)
Type
- Sensory (ascending)
# of Neurons
- 3
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16
Q

Where is the 1st Order Neuron of the Lateral Spinothalamic Tract?

A
  • Dorsal Root Ganglion (DRG)
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17
Q

Where does the 1st Order Neuron of the Lateral Spinothalamic Tract synapse with the 2nd Order Neuron?

A
  • In the Dorsal Horn of the Spinal Cord
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18
Q

Describe the Pathway of the 2nd Order Neuron of the Lateral Spinothalamic Tract? (5)

A
  • Synapsed by the 1st Order Neuron in the Dorsal Horn of the Spine
  • Decussates (crosses midline) to the contralateral side
  • Ascends through the lateral column of the spinal cord
  • Axons of 2nd Order Neuron travel to the Thalamus
  • Synapses with the 3rd Order Neuron at the Thalamus
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19
Q

Where does the 3rd Order Neuron of the Lateral Spinothalamic Tract project Sensory Information? What kind of information is it?

A

Location
- The sensory areas of the cortex
Information
- Pain and Temperature

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20
Q

What is the function of the Anterior Spinothalamic Tract? Is it Sensory or Motor? How many Neurons Does it have?

A
Function
- Conveys Information about non-discriminative (crude) touch
Type 
- Sensory
# of Neurons
- 3
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21
Q

Where is the 1st Order Neuron of the Anterior Spinothalamic Tract Located?

A
  • The Dorsal Root Ganglion (DRG)
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22
Q

Where does the 1st Order Neuron of the Anterior Spinothalamic Tract synapse with the 2nd Order Neuron?

A
  • Dorsal Horn of the Spinal Cord
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23
Q

Describe the Pathway of the 2nd Order Neuron of the Anterior Spinothalamic Tract (5)

A
  • 1st Order Neuron synapses with it at the Dorsal Horn
  • It Decussates to the contralateral side
  • Travels up the Spinal Cord within the anterolateral column
  • Axon of 2nd Order Neuron travel up to the Thalamus
  • Synapses with the 3rd Order Neuron in the Thalamus
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24
Q

Where will the 3rd Order Neurons of the Anterior Spinothalamic Tract project information? What information does it send?

A

Location
- Sensory Area of the cortex
Type
- Non-Discriminative (crude) Touch

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25
Q

What is the Function of the Dorsal Spinocerebellar Tract? sensory or motor? How many Neurons?

A

Function
- Convey information about unconscious proprioception from joint and muscles of the lower limb and trunk
Type
- Sensory
Neurons
- 2 (exception to the 3 neuron rule of sensory tracts)

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26
Q

Where is the 1st Order Neuron of the Dorsal Spinocerebellar Tract?

A
  • Dorsal Root Ganglion
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27
Q

Where does the 1st Order Neuron of the Dorsal Spinocerebellar Tract synapse with the 2nd order neuron?

A
  • The Dorsal Horn
28
Q

Describe the 2nd Order Neuron pathway of the Dorsal Spinocerebellar Tract (4)

A
  • Synapsed by 1st Order Neuron at the Dorsal Horn
  • Axons travel in the lateral column of the spinal cord
  • Passes through the inferior cerebellar peduncle
  • Axons synapse onto the ipsilateral cerebellar hemisphere
29
Q

Where does the 2nd order neuron of the Dorsal Spinocerebellar Tract pass information? What is that information?

A

Location
- Cerebellar hemisphere
Type
- Unconscious Proprioception from joints and muscles of lower limb and trunk

30
Q

What are the Two classifications of Motor Tracts?

A
  • Pyramidal Tracts

- Extrapyramidal Tracts

31
Q

Where do Pyramidal Motor Tracts convey motor information from? What does that information do?

A

Location
- Cortical motor regions (primary motor cortex of the frontal lobe)
Function
- Control muscles in the limbs and trunk

32
Q

What are the two Pyramidal Motor Tracts?

A
  • Lateral Corticospinal Tract

- Ventral Corticospinal Tract

33
Q

Where do Extrapyramidal Motor Tracts convey information from? what does that information do?

A

Location
- Nuclei of the Brainstem and Cerebellum
Function
- Convey Regulatory motor Information (postural/subconscious in nature)

34
Q

What are the 4 Extrapyramidal Tracts?

A
  • Rubrospinal Tract
  • Tectospinal Tract
  • Vestibulospinal Tract
  • Reticulospinal Tract
35
Q

How many neurons do Motor Tracts have? What are their names?

A
# of Neurons
- 2
Names
- Upper Motor Neuron 
- Lower Motor Neuron
36
Q

What is the difference between the location of Upper Motor Neurons in Pyramidal vs Extrapyramidal Motor Tracts?

A

Pyramidal
- Primary Motor Cortices
Extrapyramidal
- Nuclei of Brainstem and Cerebellar Cortex

37
Q

Where are the Lower Motor Neurons located for Pyramidal and Extrapyramidal motor tracts? Where do they exit the spinal cord? where do they go?

A
Location 
- Both are located in the Anterior Horn of the Spinal Cord
Exit
- Through the ventral root
Go
- Target muscle: to innervate it
38
Q

What are the two Corticospinal Tracts? What type of motor tract are they? what are their functions?

A
Corticospinal Tracts
- Lateral Corticospinal Tract
- Ventral Corticospinal Tract
Type
- Pyramidal (primary motor)
Functions
- Motor control of muscles of limbs and the trunk
39
Q

Where do the Axons of the Upper Motor Neurons of the Corticospinal tracts descend through?

A
  • The Brainstem
40
Q

What happens to the Axons of the Upper Motor Neurons of the Corticospinal Tract at the Caudal Medulla?

A
  • Majority of the fibers decussate at the pyramidal decussation
  • Some fibers stay on the same side
41
Q

What happens to the fibers of the Corticospinal Tracts that Decussate at the Caudal Medulla?

A
  • they become the lateral corticospinal tract

- Travel within the lateral column of the spinal cord

42
Q

What happens to the fibers of the corticospinal tract that do not decussate at the casual medulla?

A
  • They become the Ventral Corticospinal Tract
  • Travel within the ventral column of the spinal cord
  • They then decussate at the level of the target muscle they will innervate
43
Q

Where do the Upper Motor Neurons synapse with the Lower Motor Neurons?

A
  • The ventral horn at the level of the target muscle they will innervate
44
Q

What do the Lower Motor Neurons do after the Upper Motor Neurons synapses with them?

A
  • Exit the Spinal Cord via the Ventral Root

- Innervate a target muscle

45
Q

What are the Main Functions of the Brainstem? (3)

A
  • Passageway for all ascending and descending tracts between the brain and the spinal cord
  • Contains the nuclei of Cranial Nerve III-XII
  • Regulation of vital autonomic behaviors (e.g. respiration, heart rate, alternes, etc.)
46
Q

What kind of nerve tract is the rubrospinal tract?

A
  • An Extrapyramidal Motor Tract
47
Q

Where are the Upper Motor Neurons of the Rubrospinal Tract Located?

A
  • The Red Nucleus of the Midbrain
48
Q

Where do the Axons of the Upper Motor Neurons of the Rubrospinal Tract decussate? Where do they descend? Where do they synapse with the Lower Motor Neurons?

A
Decussation
- Level of the Midbrain
Descent
- Through Medulla Oblongata
- Lateral Column of spinal cord
Synapse
- Ipsilateral Ventral Horn
49
Q

From a surface anatomy perspective, where is the Medulla located?

A
  • Most inferior part of the brainstem
50
Q

From a surface anatomy perspective, what are the two divisions of the medulla?

A
  • Closed: inferior or caudal part

- Open: superior or rostral part

51
Q

What does the Open Medulla open up to posteriorly?

A
  • The 4th Ventricle
52
Q

What are the three sections of the brain stem and their location identifiers? What is located just posterior to the brainstem?

A
Sections
- Midbrain: Most superior part
- Pons: Largest part/ middle part
- Medulla Oblongata: most inferior part
Posterior to Brainstem
- Cerebellum
53
Q

What is located between the Brainstem and the Cerebellum?

A
  • 4th Cerebral Verticle
54
Q

What is Identifiable from a transverse cross-section of the Medulla? (8)

A
  • 4th Ventricle: Posterior Aspect
  • Cranial Nerve XII Nucleus: Just anterior to the 4th Ventricle
  • Cranial Nerve X Nucleus:
  • Cranial Nerve VIII Nuclei: Posterior to X and XII
  • Reticular Formation: Anterior to the Nuclei
  • Inferior Olivary Nucleus
  • Corticospinal Tracts Travelling in the Pyramids
  • Medial Lemniscus
55
Q

What are the Functions (4) of the Reticular Formation? where is it found? What happens if it does not work?

A

Functions
- Visceral Reflexes: heart rate, breathing rate, vomiting, and hiccup
- Modulates Pain: control and subside pain
- Alertness: regulating alertness of the entire nervous system (puts you to sleep and wakes you up)
- Connection: Connects everything to everything
Location
- Entire Brainstem
Not working
- Coma

56
Q

What does the Inferior Olivary Nucleus do?

A
  • cooperates with cerebellum

- helps when learning new motor skills

57
Q

From a surface anatomical perspective, what is identifiable on the pons? (4)

A
  • Located superior to the medulla and inferior to the midbrain
  • Convex Anteriorly
  • Cranial Nerve V emerges from the anterolateral surface
  • Cranial Nerves VI-VIII emerge from the Pontomedullary Sulcus
58
Q

What connects the Cerebellum to the Brainstem? how?

A
  • The Pons

- The middle and superior cerebellar peduncles

59
Q

How does the Brainstem connect to the Diencephalon?

A
  • The Midbrain: Superiorly
60
Q

What is identifiable on the anatomical surface of the Midbrain? (3)

A
  • The Cranial Nerve III emerges anteriorly
  • The Cranial Nerve IV emerges Posteriorly
  • Superior and Inferior Culliculi: Paired, contains Nuclei inside
61
Q

What is Identifiable on a cross-section of the Midbrain? (7)

A
  • Cerebral Peduncles: Anteriorly
  • Red Nucleus: Rubrospinal Tract (anterior to reticular formation)
  • Substantia Nigra: lateral to red nucleus
  • CN III Nucleus: Middle
  • Reticular Formation: Lateral to the CN III Nucleus
  • Cerebral Aqueduct: Posterior
  • The Colliculi: Posterior aspect
62
Q

What do the Cerebral Peduncles contain?

A
  • Contain Crus Cerebri (the corticospinal and corticobulbar fibers: from cortex to the brainstem)
63
Q

What is the Cerebral Aqueduct? where is it identifiable?

A

Cerebral Aqueduct
- The narrowing of the 4th Ventricle
Location
- Visible in the cross-section of the midbrain

64
Q

What happens if there are Lesions on the Red Nucleus?

A
  • Tremor: shakings of the body
  • Called the Intention Tremor
  • Only a tremor when asked to do something
65
Q

What happens if there is a lesion in the Substantia Nigra?

A
  • Parkinsons: loss of gross movements

- Resting Tremor: tremors during sedentary time