Week 8 Flashcards
What is the primary function of the Prefrontal Cortex in the motor system?
Planning complex behavior and deciding to initiate an action.
The Prefrontal Cortex specifies the goal but does not dictate the precise movements.
What role does the Premotor Cortex play in movement?
Sends instructions from the Prefrontal Cortex and organizes complex movement sequences.
It does not specify how the movements are executed.
What is the role of the Primary Motor Cortex?
Responsible for executing skilled movement.
It directly sends commands to muscles to carry out movements.
Which neurons control muscle movement?
Alpha motor neurons.
They exit the spinal cord and synapse upon muscle fibers.
What neurotransmitter is involved in muscle contraction?
Acetylcholine (ACh).
ACh crosses the neuromuscular junction to bind to muscle fiber receptors.
What are the four major regions of the spinal cord?
- Cervical
- Thoracic
- Lumbar
- Sacral
Each region controls different parts of the body.
How do alpha motor neurons communicate with muscle fibers?
They release acetylcholine (ACh) which binds to receptors on muscle fibers, triggering contraction.
Sodium ions (Na+) enter the muscle cell, leading to muscle shortening.
What is the function of central pattern generators (CPGs)?
Control repetitive behaviors like walking, chewing, and breathing.
CPGs can operate without constant brain input but can be influenced by higher brain areas.
What is the relationship between the primary motor cortex and body movement?
The left primary motor cortex controls right side movements, and vice versa.
This is due to the crossing of corticospinal neurons at the medulla.
What two pathways do corticospinal neurons form?
- Lateral corticospinal tract (crosses over) → controls limbs and fingers
- Ventral corticospinal tract (stays on the same side) → controls trunk and core muscles
These pathways are crucial for the execution of motor commands.
Where is the primary motor cortex located?
The precentral gyrus, just anterior to the central sulcus.
It lies in the frontal lobe, adjacent to the primary somatosensory cortex.
True or False: The primary motor cortex has a body map that is organized in a very orderly manner.
False.
Modern imaging shows a complex, patchy organization of the body map.
What is the role of the supplementary motor area?
Active during the conscious desire to move.
It is involved in planning and preparing for movements.
What happens when the premotor cortex is damaged?
Sequences cannot be coordinated, and goals cannot be accomplished.
This highlights the importance of the premotor cortex in planning movements.
What does the prefrontal cortex help to maintain?
Movement goals.
It ensures actions align with long-term objectives.
What is the role of the frontal eye fields?
Directing voluntary eye movement and tracking moving objects.
They help predict the upcoming location of an object.
Fill in the blank: The spinal cord is comprised of four major regions: Cervical, Thoracic, ______, and Sacral.
Lumbar
What is the hierarchy of movement control in the brain?
- Prefrontal Cortex (highest level)
- Motor Cortex and Cerebellum (middle level)
- Brainstem and Spinal Cord (lowest level)
This hierarchy reflects the complexity of movement planning and execution.
