Spinal Cord, Brainstem And Motor Fnx II (Obj. 1 and 2)

Question 1

Most fibers of the CBT terminate where?

Answer 1

• In the RETICULAR formation

- Near the Cranial Nerve Nuclei

Question 2

CST Lesions can lead to what?

Answer 2

1. Hyper-Tonia
2. Hyper-Reflexia
3. Clonus (Spasm)
4. Muscle weakness

Question 3

Rubro-Spinal Tract Characteristics

• Origin
• Decussation
• Descends
• Responsible for

Answer 3

• Originates in the RED Nucleus
• Decussates in the MIDBRAIN
• Descends in LATERAL Column (Funiculus)
• Responsible for Large Muscle MOVEMENT and some FINE motor movement

Question 4

Cortico-Bulbar Tract Characteristics

Answer 4

• UMN of the CRANIAL Nerves
• Innervating the Face, Head, and Neck
• Contain ASSOCIATION Neurons

Question 5

The Lateral CST supplies ____ while the Anterior CST supplies _____.

Answer 5

1. All Levels of the Spinal Cord

2. Neck and Upper Limbs

Question 6

What is thought to be the fxn of the Olivo-Spinal Tract?

Answer 6

• Involved into REFLEX movement

- Recent studies have called into question its existence

Question 7

What % of Upper MN decussate in the Pyramidal System and where?

Answer 7

• 75% to 85%

- Decussate in the Pyramids

Question 8

Red Nucleus Projections Stimulate ____ and Inhibit ____.

Answer 8

• Flexors

- Extensors (Anti-gravity)

Question 9

Olivospinal tract originates where?

Answer 9

The Medulla in INFERIOR Olivary Nucleus

Question 10

Reticular formation is a network of what?

Answer 10

• Nuclei w/in the Brainstem

- In both the PONS and the Medulla

Question 11

What do the UMN form after decussation?

Answer 11

Forms the LATERAL Cortico-Spinal Tracts

Question 12

Effects of Lesions to the Rubro-Spinal Tract

Answer 12

• Impairment of DISTAL Arm and Hand movement
• Intention Tremors
• May take over for injured CST in some animals

Question 13

The Cortico-Spinal Tract is also known as the _____.

Answer 13

Pyramidal Tract

Question 14

Lateral VST

Answer 14

• Major part of tract
• IPSILATERAL
• Upright posture and Balance

Question 15

Anterior CS Tract Characteristics

Answer 15

• Made up of UNCROSSED fibers
• Cross near the level of Synapse with LMN’s
• Supply NECK and Upper Limbs

Question 16

Medial VST

Answer 16

• Projects Bilaterally
• Controls LMN of CN 11
• Projects Indirectly to CN 6 and 3

Question 17

Vestibulo-Spinal Tract Characteristics

• Originates
• Goal
• Descends
• Synapses

Answer 17

• In the Vestibular Nuclei in the Medulla
  (Receives input from CN8)
• Maintain BALANCE
• Descends in ANT. Column (Funiculus)
• Synapses w/ LMNs to EXTENSOR Muscles
  (Upright Posture)

Question 18

Where does the Pyramidal System upper MN originate?

Answer 18

Motor Cortices

Question 19

Red Nucleus

Answer 19

• Evolutionary Primitive portion of the Brain

- Relay Center

Question 20

Components of the Pyramidal system

Answer 20

1. Cortico-SPINAL Tract

2. Cortico-BULBAR Tract

Question 21

What must occur for complete paralysis in CST?

Answer 21

If BOTH the Pyramidal and Extrapyramidal systems are involved in the lesions

Question 22

Lesions of the ExP Subcortical Nuclei can lead to what?

Answer 22

• Parkinson’s Disease
• Side Effects of Anti-Psychotic Drugs
• Dystonia

Question 23

Do all the fibers in the CS Tract Decussate in the Lower Medulla?

Answer 23

• No only 80%

- Some continue down IPSILATERALLY in ANTERIOR CS Tract where they decussate near the synapse of LMN

Question 24

What is the Pyramidal System?

Answer 24

• Motor Tracts that pass through the MEDULLARY Pyramids

Question 25

Fxn of the Reticulo-Spinal Tract

Answer 25

- Mediates Larger movements of Trunk and Limbs - When Standing it excites axial extensors - Controls Alpha and Gamma Neurons - Mediates Circulatory system and breathing - Can modulate PAIN info

Question 26

When do the remaining fibers from the CS Tract decussate?

Answer 26

When Exiting the Spinal Cord

Question 27

CBT Lesion Characteristics

Answer 27

- Lesions typically UNILATERAL | - Result in MILD muscle weakness

Question 28

Fxn of the Rubio-Spinal Tract

Answer 28

Closely related to Cerebellar Fxn

Question 29

Pathway of the CS Tract

Answer 29

``` Origin -> Internal Capsule —> Medullary Pyramids ——> 80% X in LOWER Medulla (Most) ———> LATERAL Columns of Spinal Cord (Lat. CS Tract) ```

Question 30

Extrapyramidal means what?

Answer 30

Other motor pathways that do NOT pass through the MEDULLARY Pyramids

Question 31

Pontine vs Medullary Reticular Nuclei

Answer 31

Pontine - Uncrossed - Stimulate Flexors and Extensors - Maintenance of Movement Medullary - Uncrossed AND Crossed - Inhibitory effect on Flexors and Extensors

Question 32

Association Neurons

Answer 32

- Leave RF and synapse in CN Nuclei | - Synapse w/ LOWER MN

Question 33

Extrapyramidal System Tracts include what?

Answer 33

1. Rubro-Spinal 2. Reticulo-Spinal 3. Vestibulo-Spinal 4. Olivo-Spinal RRVO

Question 34

Most UMN in the Pyramidal system Synapse where?

Answer 34

With ASSOCIATION Neurons in the Spinal Cord Central Gray

Question 35

Where do the remainder of the UMN decussate? What do they form?

Answer 35

- Near the Synapse with the LOWER MN | - Form the ANTERIOR Cortico-Spinal Tracts

Question 36

Extrapyramidal System Characteristics

Answer 36

- This system includes pathways that contribute to motor control but that are not part of the CS system - Includes Descending Motor Tracts that do not pass through Medullary Pyramids or CBT

Question 37

NT of Betz cells

Answer 37

Glutamate

Question 38

Betz Cells are also known as what?

Answer 38

Giant Pyramidal Cells

Question 39

The VST can be divided into what?

Answer 39

- Lateral and Medial VST

Question 40

Lateral CS Tract Characteristics

Answer 40

- Made up of CS Fibers that have crossed in the MEDULLA | - Supply ALL Levels of the Spinal Cord

Question 41

Fxns of the CS Divisions

Answer 41

- Add speed and agility to the conscious movements (Especially the Hand) - Provides a High degree of Motor Control (Especially in the fingers)

Question 42

Projections of the Red Nucleus

Answer 42

1. Rubio-Spinal Tract (Contralateral) 2. Inf. Olive (Ipsilateral)

Question 43

What are the Origins of the CS Tract?

Answer 43

1. Primary Motor Cortex (30%) 2. Premotor Cortex (30%) 3. Somatosensory Area (40%)

Question 44

Characteristics of Betz cells

Answer 44

- Large Cells - Large fibers - Transmit 70m/sec (Fastest in CNS) - Make up 3% of fibers in the tract - Sends collateral back to Cortex

Question 45

CS Tract Division

Answer 45

1. LATERAL | 2. ANTERIOR (Ventral)

Question 46

Where are Betz cells located?

Answer 46

In the Motor Cortex