Motor Action and Control Part 2 Flashcards
What is your vestibular Tract?
Includes several neural pathways that contribute to balance and eye movement coordination:
What is your alpha motor neuron?
Associated with your final common pathway
What does your alpha motor neuron activate?
Muscle Cells to produce Force
What does your gamma motor neuron activate?
Maintaining sensory ability
What does the Quadricep Femoris Muscle contain?
A femoral nerve - this generates a knee extension
Is the sensory information from the Femoral nerve the same?
No - differs depending on stimulus
How do we fine tune the degree of an alpha motor neuron activation?
Network Connections with sensory systems
What do Medial Pathways coordinate?
Axial and Proximal Muscles
Balance and Postural Stability
What are the Three Components of the Medial Descending Pathways?
1.) Vestibulospinal Pathway
2.) Reticulospinal Pathway
3.) Tectospinal Pathway
Where do the three components of the medial descending pathway project to and terminate at?
- Interneurons
- Medial Motor Neurons
Vestibulospinal tract origin?
Vestibular Nuclei
What is the Function of the Vestibulospinal Tract?
Control of Balance and Posture, Standing and Tipping
Detects change in head and Body Position
What are vestibular nuclei?
1st order vestibular afferents
Cell Bodies in Vestibular Ganglion
How do the axons travel in the Vestibular Nuclei?
Via the cranial nerve VIII to vestibular nuclei and cerebellum
What does extra-ocular nuclei control?
Eye Movement
What does the Spinal Cord Control?
Controls Head and Body Position
What does the Thalamus Control?
Ventriposteror Inferior Nucleus
What does the cerebellum control?
Postural Adjustments
What are the two types of descending tracts in the vestibular nuclei?
Lateral Tract and Medial Tract
What does the Lateral Tract contain?
Ipsi lateral (Same side)
Long Projections
Coordinates Muscles to Walk Upright
What does the Medial Tract of the Vestibular Nuclei do?
Bi lateral (travels to mid cervical levels)
Short Projections
Coordinates Eye Movement and Head Position
What are the inputs of the vestibular tract?
Inner Ear, cerebellum
What are the Outputs of the Vestibular Tract?
Spinal cord, Sensory Cortex, Cerebellum, Eye Muscles (extra-ocular nuclei)
What is the reticulospinal tract?
A descending motor pathway in the spinal cord that controls muscle tone, action, and locomotion:
Where does the reticulospinal tract originate?
In the reticular formation located in the medulla oblongata
What are the two tracts of the reticuloospinal tract?
1.) Pontine Reticular Formation
- Exists the Ipsi-lateral at all spinal levels
2.) Medullary Reticular Formation
- exits some bi-lateral at all spinal levels
Where does the reticulospinal tract receive its inputs from?
The vestibular system
What is the function of the reticulospinal tract?
Generating the flexion response to damaging stimulus
What is the RIII reflex (flexion response)?
Spinal and supraspinal reflexes (motor neurons that withdraw from stimulus)
What are the features of pain afferent receptors?
- Same location as touch/cell body receptors
- The cell body is in the Dorsal Root Ganglion.
- small diameter, unmyelinated, slow
What does an electromyogram measure?
Muscle Cell Membrane Action Potentials (reflexes, not contraction)
What was the RIII measurement?
90-130ms after stimulus (longer than the tendon tap)
What were the distraction studies used in the Flexor Reflex test?
- Mental Imagery
- Music
- Brush Task
- Concentration-on-Pain Task
What did the study find regarding the R3 reflex when using mental imagery?
R3 reflex was enhanced
What did the study find with music?
R3 reflex remained (no effect)
What did the study find with brush ?
R3 was blocked
What did the study find when concentrating on pain?
R3 slightly decreased
What is the Tectospinal Tract?
Part of the extrapyramidal system that controls the head and eye movements, and is involved in visual and auditory reflexes
Where does the Tectospinal Tract originate?
Tectum part of the midbrain, controlled by the cerebral cortex.
What is the Midbrain Function?
Transfer information between the brain and the spinal cord
Sensory and Movement Control
What are the two components of the Tectospinal Tract?
Superior Colliculus (optic)
Inferior Colliculus
What is the Superior Colliculus?
Receives inputs from the eyes
What is the inferior colliculus?
Receiving input from the ears and sending auditory information to the thalamus
What is the Rubrospinal Tract responsible for?
Controlling distal limb muscles and fine-motor control.
What is the Corticospinal Tract?
Provides direct projections to motor neurons
What are the two parts of the corticospinal tracts?
1.) Corticospinal Fibres: innervate trunk and limb muscles
2.) Corticobulbar Fibres: cranial nerve motor nuclei (controls facial muscles)
What do corticospinal tracts refer to?
Upper motor neurons (CNS) that innervate lower motor neurons (skeletal muscle) as well as muscle fibres
How many axons in human movement?
1 million extending through the corticospinal (pryimadial) tract
What is another word for corticospinal tract?
The pyramidal tract
What are the two types of cells in the pyramidal tract?
1.) Pyramidal Cells
2.) Stellate Neurons
What are pyramidal cells and where do they project to?
Output neurons from the motor cortex
Project to: basal ganglia, thalamus, brain stem.
What are Stellate neurons?
Function as Interneurons
Where do Pyramidal Cells and Stellate neurons originate?
In the Primary Motor Cortex (Broadmann’s Area 4)
Pre-Motor (Area 6)
Areas 3,2,1 and sensory cortex
What is the internal capsule?
A white matter structure, as a two-way tract, carrying ascending and descending fibers, to and from the cerebral cortex.
What is the Medullary Pyramid?
A collection of axons forming the pyramidal tract
What is Pyramidal Decusation?
Where axons cross to contra-lateral side of the body in a descending pathway
What do the dorsal part of lateral columns form?
The lateral cortical spinal tract
What is the ventral corticosponal tract?
Uncrossed fibres that project bi-laterally to medial column (axial muscles)
