Motor Systems

Question 1

What does the primary motor cortex do?

Answer 1

Controls execution of movement
-general, low threshhold, gets things going

Question 2

What does the supplementary motor area do?

Answer 2

SEQUENCE, PREVIOUS PATTERN, CONTROL, IMAGERY

-coordination and execution of sequences of movements
- attainment of motor skills (selecting a mvmt based on previous mvmt patters)
- executive control of movment
-mental imagery of motor tasks

Question 3

What does the premotor cortex do?

Answer 3

MILK EX, RSB stretch

-selection of appropriate motor plans for voluntary movements (exsternal and internal cues- pain vs stairs)
-mirror motor neurons (why coaches stretch in front of room in RSB)

overall analyse and dictate motor patterns based on sensory cue

Question 4

explain the dirty vs clean milk example as it relates to the premotor cortex

Answer 4

premotor cortex: selection of appropriate motor plans
you see one dirty milk and one clean milk glass, and without thinking about it you automatically wash the dirty and sip the clean

Question 5

difference between lateral and medial sides of the premotor cortex- where does each side get movements in response to? and example

Answer 5

lateral: exsternal cue (stairs in front of me)
medial: internal cue (pain when i move)

Question 6

what are the 2 lateral motor systems

Answer 6

lateral corticospinal tract
rubrospinal tract

Question 7

what does the lateral corticalspinal tract do

Answer 7

MOVMENT: dexterous joint, reflex ceiling

controls movement of EXSTREMITIES
- rapid, dexterous (natural precision/efficency) movements at individual digits or joints
- modulatory control of myotactic reflex (reflex ceiling- Constant buzz so he’s traveling down so you don’t overshoot with your reflex)

Question 8

lateral corticalspinal tract pathway

Answer 8

priMC, suplementary motor area, and premotor area decend via internal capsule to brainstem
->
decussates at pyramidal decussation
->
descends contralateral spinal cord and lateral column until the level of their target spinal nerve
->
Synapse onto anterior horn cells and lateral intermediate zone
-> project out of the spinal cord via ventral horn to target muscles

Question 9

What does the anterior corticospinal tract do?

Answer 9

controls bilateral nack and trunk muscles

Question 10

anterior corticospinal tract pathway

Answer 10

PriMC, SMS, PreMA decend via internal capsule to brainstem
(remain ipsilateral and descend spinal cord in anterior column)
->
Synapse onto anterior horn cells bilaterally in a medial intermediate zone (for back up)
->
Project out of the spinal cord via ventral horn to axial musculature
->
85% desiccates into LCST (remaining 15% stay ipsalateral to become ACST)

Question 11

In the anterior corticospinal tract, why does the first order neuron synapse onto anterior horn cells bilaterally in the medial intermediate zone?

Answer 11

For back up, this is why the trunk is more stable than a limb

Question 12

What is the internal capsule made of

Answer 12

white mater axons

Question 13

boarders of internal capsule

Answer 13

medial- thalamus and caudate
lateral- globus pallidus and putamen

Question 14

somatotopic organization of the internal capsule

Answer 14

Question 15

What types of fibers are in the anterior limb of the internal capsule? what cortical regions?

Answer 15

thalamic and brain stem fibers
Pre-frontal and parietal cortical regions

Question 16

What are the fibers of the anterior limb in the internal capsule associated with

Answer 16

emotion, motivation, cognition processing, and decision making

Question 17

What are the fibers in the Posterior limb

Answer 17

Descending motor fibers from frontal lobe (brainstem and spinal cord)

Question 18

What are the fibers of the posterior limb in the internal capsule associated with

Answer 18

ascending somatosensory fibers from spinal cord

Question 19

somatotopic organization of the corticospinal tract and corticobulbar tract

Answer 19

(both bc they dont split until spinal cord)

Question 20

somatotopic organization of the anterior and lateral corticospinal tract

Answer 20

Question 21

what does the ruberospinal tract do

Answer 21

controls flexors of exstremities
- tone, inhibit exstensors

-myotactic reflex floor
-flexor withdraw ceiling

Question 22

ruberospinal tract pathway

Answer 22

Red nucleus, immediately desiccates via ventral tegmental desiccation and travels down contralat brain stem to spinal cord
->
Travels through spinal cord and lateral column until the level of their target spinal nerve
->
Synapse onto anterior horn cells in lateral intermediate zone
-> project out of the spinal cord via ventral horn to target muscles

Question 23

what does the reticulospinal tract do?

Answer 23

Autonomic posture and gait related movements (helps you walk synchronize)
- pontine: inhibit limb flexors and excite extensors

-medullary: excite limb flexors and inhibit extensors

Question 24

reticulospinal tract pathway

Answer 24

Question 25

what does the Tectospinal tract do

Answer 25

Controls coordination of head and eye-movement effect: Head movements to match eye movements

Question 26

tectospinal tract pathway

Answer 26

Question 27

where does a peripheral nerve start

Answer 27

at the alpha motor neuron (which exit the spinal cord from the ventral horn)

Question 28

where is the cervical plexus and what does it intervate

Answer 28

C3-5, diaphragm

Question 29

Where is the brachial plexus and what does it intervate

Answer 29

C5-T1, UE

Question 30

where is the lumbosacral plexus and what does it intervate

Answer 30

L1-S4, LE

Question 31

Myotome is a group of muscles innervated by _________

Answer 31

a single nerve root

Question 32

Describe what happens at the synapse of a neuromuscular junction

Answer 32

action potential from presynaptic motor neuron triggers ACh into synaptic cleft -> ACh binds, makes Na+ to flow into muscle fiber -> EPSP ("end plate potential" in NMJ) -> AP travels down muscle fiber to facilitate muscle contraction -> ACh is broken down by acetylcholinesterase

Question 33

What is the EPSP in the muscle fiber called in the NMJ

Answer 33

end plate potential

Question 34

What 2 key things do you find in a motor end plate

Answer 34

junctional folds, and ACH receptors

Question 35

why are junctional folds there

Answer 35

more surface area, more receptors, faster

Question 36

how is a motor unit defined

Answer 36

defined as 1 motor neuron and all the fibers it intervates

Question 37

Diffrence between type 1a, 2a, and 2b fibers

Answer 37

Question 38

How many muscle fibers are correlated with one neuromuscular junction

Answer 38

1

Question 39

How many muscle fibers are correlated with one motor neuron

Answer 39

1+