Spinal Cord, Brainstem And Motor Fnx II (Obj. 1 and 2) Flashcards
Most fibers of the CBT terminate where?
- In the RETICULAR formation
- Near the Cranial Nerve Nuclei
CST Lesions can lead to what?
- Hyper-Tonia
- Hyper-Reflexia
- Clonus (Spasm)
- Muscle weakness
Rubro-Spinal Tract Characteristics
- Origin
- Decussation
- Descends
- Responsible for
- Originates in the RED Nucleus
- Decussates in the MIDBRAIN
- Descends in LATERAL Column (Funiculus)
- Responsible for Large Muscle MOVEMENT and some FINE motor movement
Cortico-Bulbar Tract Characteristics
- UMN of the CRANIAL Nerves
- Innervating the Face, Head, and Neck
- Contain ASSOCIATION Neurons
The Lateral CST supplies ____ while the Anterior CST supplies _____.
- All Levels of the Spinal Cord
2. Neck and Upper Limbs
What is thought to be the fxn of the Olivo-Spinal Tract?
- Involved into REFLEX movement
- Recent studies have called into question its existence
What % of Upper MN decussate in the Pyramidal System and where?
- 75% to 85%
- Decussate in the Pyramids
Red Nucleus Projections Stimulate ____ and Inhibit ____.
- Flexors
- Extensors (Anti-gravity)
Olivospinal tract originates where?
The Medulla in INFERIOR Olivary Nucleus
Reticular formation is a network of what?
- Nuclei w/in the Brainstem
- In both the PONS and the Medulla
What do the UMN form after decussation?
Forms the LATERAL Cortico-Spinal Tracts
Effects of Lesions to the Rubro-Spinal Tract
- Impairment of DISTAL Arm and Hand movement
- Intention Tremors
- May take over for injured CST in some animals
The Cortico-Spinal Tract is also known as the _____.
Pyramidal Tract
Lateral VST
- Major part of tract
- IPSILATERAL
- Upright posture and Balance
Anterior CS Tract Characteristics
- Made up of UNCROSSED fibers
- Cross near the level of Synapse with LMN’s
- Supply NECK and Upper Limbs
Medial VST
- Projects Bilaterally
- Controls LMN of CN 11
- Projects Indirectly to CN 6 and 3
Vestibulo-Spinal Tract Characteristics
- Originates
- Goal
- Descends
- Synapses
- 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)
Where does the Pyramidal System upper MN originate?
Motor Cortices
Red Nucleus
- Evolutionary Primitive portion of the Brain
- Relay Center
Components of the Pyramidal system
- Cortico-SPINAL Tract
2. Cortico-BULBAR Tract
What must occur for complete paralysis in CST?
If BOTH the Pyramidal and Extrapyramidal systems are involved in the lesions
Lesions of the ExP Subcortical Nuclei can lead to what?
- Parkinson’s Disease
- Side Effects of Anti-Psychotic Drugs
- Dystonia
Do all the fibers in the CS Tract Decussate in the Lower Medulla?
- No only 80%
- Some continue down IPSILATERALLY in ANTERIOR CS Tract where they decussate near the synapse of LMN
What is the Pyramidal System?
- Motor Tracts that pass through the MEDULLARY Pyramids
Fxn of the Reticulo-Spinal Tract
- 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
When do the remaining fibers from the CS Tract decussate?
When Exiting the Spinal Cord
CBT Lesion Characteristics
- Lesions typically UNILATERAL
- Result in MILD muscle weakness
Fxn of the Rubio-Spinal Tract
Closely related to Cerebellar Fxn
Pathway of the CS Tract
Origin -> Internal Capsule —> Medullary Pyramids ——> 80% X in LOWER Medulla (Most) ———> LATERAL Columns of Spinal Cord (Lat. CS Tract)
Extrapyramidal means what?
Other motor pathways that do NOT pass through the MEDULLARY Pyramids
Pontine vs Medullary Reticular Nuclei
Pontine
- Uncrossed
- Stimulate Flexors and Extensors
- Maintenance of Movement
Medullary
- Uncrossed AND Crossed
- Inhibitory effect on Flexors and Extensors
Association Neurons
- Leave RF and synapse in CN Nuclei
- Synapse w/ LOWER MN
Extrapyramidal System Tracts include what?
- Rubro-Spinal
- Reticulo-Spinal
- Vestibulo-Spinal
- Olivo-Spinal
RRVO
Most UMN in the Pyramidal system Synapse where?
With ASSOCIATION Neurons in the Spinal Cord Central Gray
Where do the remainder of the UMN decussate?
What do they form?
- Near the Synapse with the LOWER MN
- Form the ANTERIOR Cortico-Spinal Tracts
Extrapyramidal System Characteristics
- 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
NT of Betz cells
Glutamate
Betz Cells are also known as what?
Giant Pyramidal Cells
The VST can be divided into what?
- Lateral and Medial VST
Lateral CS Tract Characteristics
- Made up of CS Fibers that have crossed in the MEDULLA
- Supply ALL Levels of the Spinal Cord
Fxns of the CS Divisions
- Add speed and agility to the conscious movements
(Especially the Hand) - Provides a High degree of Motor Control
(Especially in the fingers)
Projections of the Red Nucleus
- Rubio-Spinal Tract
(Contralateral) - Inf. Olive
(Ipsilateral)
What are the Origins of the CS Tract?
- Primary Motor Cortex (30%)
- Premotor Cortex
(30%) - Somatosensory Area
(40%)
Characteristics of Betz cells
- Large Cells
- Large fibers
- Transmit 70m/sec (Fastest in CNS)
- Make up 3% of fibers in the tract
- Sends collateral back to Cortex
CS Tract Division
- LATERAL
2. ANTERIOR (Ventral)
Where are Betz cells located?
In the Motor Cortex
