Ascending + Descending Tracts 26

Question 0

Def. Nuclei

Answer 0

Cluster of nerve cells within the CNS

Question 1

Def. Ganglia

Answer 1

• structure containing nerve cell bodies outside (generally) of the central nervous system
• mass of grey matter within the CNS (ie. Basal ganglia)

Question 2

Def. # order neuron

Answer 2

Neuron location in particular order

1st 2nd 3rd….

Question 3

Def. Tracts

Answer 3

Bundles of axons with common origin and common termination

Question 4

Def. Fasciculus and lemniscus

Answer 4

Other terms for bundles of axons, specific tracts we talk about for ascending

Question 5

Def. Ipsilateral

Answer 5

Same side of the body

Question 6

Def. Contralateral

Answer 6

Opposite side of the body

Question 7

Def. Decussation

Answer 7

Cross over of axons within CNS

Question 8

Peripheral nervous system includes?

Purpose?

Answer 8

Spindles, GTOs, skin receptors, joint receptors, free nerve endings

• involved in ascending tracts

Question 9

Central nervous system components?

Answer 9

Brain, brain stem, cerebellum, spinal chord

Question 10

The brainstem includes what components?

Answer 10

Midbrain
Pons
Medulla

Question 11

Spinal chord anatomy:

Grey matter contains?

Answer 11

Cell bodies
Inter neurons
Somatotopic organization

Question 12

White matter contains?

Answer 12

Myelinated axons
Ascending and descending tracts
(White because it’s myelinated)

Question 13

Ascending tracts are associated with?

Answer 13

Sensory system

- brings sensory info UP to brain

Question 14

Descending tracts are associated with?

Answer 14

Motor system

- brings motor commands DOWN to muscles

Question 15

Where is cerebral spinal fluid?

Answer 15

Flows through the central canal

Question 16

Key feature of the medulla

Answer 16

Important location where a lot of tracts Decussate “cross over”
(Also contains nuclei)

Question 17

Pons and midbrain

Answer 17

Part of the brainstem
A lot of nuclei that allow subconscious functions
(Breathing swallowing bladder control etc)

Question 18

Cerebellum

Answer 18

“Integrator” of sensory information

- fine motor control and motor learning

Question 19

Thalamus

Answer 19

‘Grand central station’
Deep within cortex
Many nuclei receive ALL sensory info: peripheral, visual, vestibular info
Transmits too all locations within the cortex
‘VPL’ ventral posteriolateral nucleus

Question 20

Central sulcus separates what parts of the brain?

Answer 20

Frontal and parietal lobes

Question 21

Dorsal column

Answer 21

Only ascending tracts
Most myelinated axons (fastest transmission)
Newer system (Proprioception, vibration, fine touch - evolved from older system ex. Pain)

Question 22

Anterolateral column of spinal chord

Answer 22

Both ascending and descending tracts
Slower tracts (less myelinated)
Older system (crude touch, pain, temp)

Question 23

Name all ascending tracts (top to bottom)

Answer 23

Fasciculus gracilis (lower limb)
Fasciculus cuneatus (upper limb muscles)
Dorsal spinocerebellar tract
Ventral spinocerebellar tract
Lateral spinothalamic tract
Anterior spinothalamic tract

Question 24

Name all the descending tracts (brain down to periphery)

Answer 24

``` Lateral corticospinal tract Medullary reticulospinal tract Pontine reticulospinal tract Lateral vestibulospinal tract Anterior corticospinal tract ```

Question 25

Descending motor output originates? Innervates? Modulates? Controls?

Answer 25

- multiple brain systems and descends through multiple tracts - alpha gamma and inter neurons within the spinal chord - modulates spinal chord neural processing - controls voluntary & reflexive movement

Question 26

Corticospinal tract transmits? Associates with? Important for?

Answer 26

- voluntary motor commands to motor neurons in SC - motor cortex associated with Contralateral muscles (axons Decussate to other side) - important in controlling skilled movements

Question 27

3 main descending tracts?

Answer 27

Corticospinal tract Vestibulospinal tract Reticulospinal tract

Question 28

3 main ascending tracts?

Answer 28

Medial leminscal system Anterolateral spinothalamic tract Spinocerebellar tract

Question 29

Pathway of the corticospinal tract

Answer 29

``` Begins motor cortex M1 Through internal capsule Partial decussation within medulla - 75-90% do (innervate limbs) - 10-25% don't (innervate axial muscles) ```

Question 30

Reticulospinal tracts coordinates what type of movement? Originates? Direction of travel? Terminates?

Answer 30

- automatic movements (locomotion and posture) - originates in "reticular formation" (2 tracts- pons and medulla) - travels ipsilateral - terminate at all SC segments

Question 31

Difference between pontine reticulospinal tract and medullary reticulospinal tract?

Answer 31

Pontine -medial -excites ipsilateral extensor muscles (help support our weight) Medullary -lateral -inhibits excitory axial muscles (help relax extensors)

Question 32

Vestibulospinal tract (VS tract) transmits?

Answer 32

Subconscious motor commands to extensor muscles to maintain balance

Question 33

Vestibular tracts signals are generated from where? Where do they go and how? What does it control?

Answer 33

- signals generated within the vestibular system (accelerations) - transmitter to vestibular nuclei via the 8th cranial nerve - controls ipsilateral muscles

Question 34

Two vestibulospinal tracts are?

Answer 34

Medial VS tract -controls neck muscles Lateral VS tract -descends directly to ipsilateral extensor muscles

Question 35

Ascending sensory pathways send what type of input?

Answer 35

Sensory input

Question 36

Ascending sensory pathways originates in?

Answer 36

Peripheral sensory receptors (first order neurons)

Question 37

Ascending sensory pathways ascend through what columns?

Answer 37

Dorsal column - medial lemniscal system Anterolateral column - spinothalamic and spinocerebellar pathways

Question 38

Medial lemniscal system transmits what type of information?

Answer 38

Transmits proprioceptive, fine touch, and vibration info from peripheral receptors to somatosensory cortex

Question 39

Medial lemniscal system tracts ascend through

Answer 39

The dorsal column

Question 40

Key feature of the axons of the medial lemniscal system?

Answer 40

Axons are the most myelinated | Fastest conduction velocity

Question 41

Sensations from one side of the body of the medial lemniscal system associate with?

Answer 41

Contralateral somatosensory cortex

Question 42

Spinothalamic tracts transmit what signals? From where? To where?

Answer 42

Transmits pain, temp, and crude touch From periphery To areas within cortex

Question 43

Receptors on one side of the body from spinothalamic tracts associate with?

Answer 43

The somatosensory cortex

Question 44

What are the two spinothalamic tracts?

Answer 44

Lateral spinothalamic tract -pain and temp Anterior spinothalamic tract -crude touch and pressure

Question 45

Spinocerebellar tracts transmits info from where? To where and why?

Answer 45

Information from the peripheral receptors (spindles! GTOs, skin etc) To the cerebellum For sensory integration

Question 46

Receptors from one side of the body of the spinocerebellar tract are associated with?

Answer 46

The ipsilateral cerebellum

Question 47

Path of the. Spinocerebellar tracts

Answer 47

Ascends in the lateral column via the dorsal and ventral spinocerebellar tracts