10_Neuro 3.1 Spinal Cord: Motor Unit & Reflexes 1

Front 1

The motor system has three major components and levels of control: (p4)
*Describe how these are networked together

Back 1

1. Cerebral Cortex
2. Brain Stem
3. Spinal cord
*Cortex can influence spinal cord directly or through brain stem then spinal cord.

Front 2

All three levels of motor systems are modulated by two independent subcortical structures: (also explain what each one does primarily)

Back 2

1. Basal Ganglia - routine, voluntary movement
2. Cerebellum - balance

Front 3

The "relay station" of the brain is:
Also, outline how it's network with other motor systems. (p4)

Back 3

Thalamus.
See pg 4 for network diagram

Front 4

What are the two general types of spinal cord neurons?

Back 4

1. Motor neurons
2. Interneurons

Front 5

Motor neurons are found in which horn of the spinal cord?

Back 5

Ventral (remember SDMV)

Front 6

Describe the somatotopic organization of the motor neurons in the spinal cord (p5)

Back 6

1. Medial MN: innervate proximal muscles that control balance, posture, movement of trunk
2. Lateral MN innervate distal muscles that control limbs and digits and control specific limb, digit movement (remember MIP and LID)

Front 7

1. Describe the two types of Interneurons?
2. What are interneurons responsible for doing?
(p5)

Back 7

1 a. Segmental Interneurons: Project within a single spinal cord level
b. Propriospinal Interneurons (the "professional spinal neurons) that transmit info between multiple spinal cord levels
2. Interneurons connect and coordinate motor neurons that contract groups of muscles for specific tasks - allow for fluid movements

Front 8

What is the major role of the Brainstem neurons?

Back 8

To modulate the action of spinal motor circuits

Front 9

How do upper motor neurons differ from lower motor neurons?

Back 9

1. Upper MNs modulate but do not control motor neurons
2. Lower motor neurons directly innervate muscles.

Front 10

What are the three medial brainstem pathways discussed in class? (p6)
Do the descend in ventral or dorsal white or gray matter?
Do they influence axial or distal muscles?

Back 10

1. Reticulospinal tract
2. Bestibulospinal
3. Tectospinal
They descend in ventral white matter
They influence axial and proximal muscles for posture.

Front 11

What is the lateral brainstem pathway duscussed in class? What nucleus does it project to the spinal cord?
Does it project in ventral or dorsal white or gray matter?
What motor units does it control?

Back 11

Rubrospinal Tract - projecting the red nucleus
It descends in the dorsal white matter.
Controls distal muscles of limbs for modulating goal-directed limb movements like reaching and manipulating.

Front 12

The major areas of the cerebral cortex include (5 areas):

Back 12

1. Primary motor cortex
2. Premotor cortex
3. Supplementary motor cortex
4. Primary Somatosensory Cortex
5. Posterior Parietal Cortex

Front 13

Describe the Primary Motor Cortex
1. Where is it
2. What does it do?

Back 13

1. Anterior to the central sulcus
2. It executes commands to motor neurons. Controls individual finger movements. Coordinates the force and direction of movements.

Front 14

What does the Premotor Cortex do?

Back 14

Integrates motor movements with sensory input

Front 15

What does the supplementary motor area do?

Back 15

1. Important in internally-driven, will-driven movements...formulate and intention to make a movement...important for planning

Front 16

What does the Primary somatorsensory cortex do?

Back 16

1. Regulates incoming sensory info in the dorsal horn.

Front 17

What does the posterior parietal cortex do?

Back 17

1. Helps localize where an object is with respect to the body

Front 18

The cerebral cortex acts on motor neurons via two descending pathways: (p9)

Back 18

1. Lateral Cortical Spinal tract
2. Ventral corticospinal tract

Front 19

1. Lateral Cortical Spinal tract Control:
2. Ventral corticospinal tract Control:

Back 19

1. Contralateral limb, digits: goal-directed reaching
2. Neck, trunk muscles; postural control

Front 20

Motor systems are organized both hierarchially and in parallel. What does this mean?

Back 20

Lower motor structures are concerned with more simple tasks. Parallel pathways means that there's reducndancy and flexibility after injury

Front 21

There are three general types of movement:

Back 21

1. Reflexive
2. Automatic postural
3. Voluntary movements

Front 22

Reflexive movements require:

Back 22

1. Spinal cord
2. Motor neurons
3. Sensory neurons
4. Brainstem neurons

Front 23

Automatic postural adjustments require:

Back 23

1. Brain stem
2. Spinal cord
3. Motor neurons

Front 24

Voluntary movemnts require:

Back 24

1. Cerebral cortex
2. brain stem
3. spinal cord
4. motor neurons