Chapter 15: Brain Control of Movement Flashcards
How are descending spinal pathways from brain divided?
Lateral Pathways
Ventromedial Pathways
Where are upper motor neuron?
Soma in cerebral cortex or brainstem
Where are lower motor neuron?
Soma in ventral horn of spinal cord for skeletal muscles of body
Soma in brainstem nuclei for skeletal muscles of head
Innervates muscle fiber
Final common pathway
What are the lateral pathways?
Corticospinal tract
Rubrospinal tract
What do lateral pathways do?
Voluntary movement of distal musculature
Under direct cortical control
Innervate distal musculature
What are the ventromedial pathways?
Tectospinal tract
Vestibulospinal tract
Reticulospinal tract
What do ventromedial pathways do?
Control of posture, locomotion, orienting, and balance
Under brainstem control
Innervate axial and proximal musculature
What is the pathway of the corticospinal tract?
- Starts in the motor cortex
- Descends the internal capsule through the midbrain and pons
- Descends the medulla and then there is pyramidal decussation
- Contralateral goes to the ventral horn of the spinal cord
What is the corticobulbar tract?
Travels with CST and provides UMN innervation to LMNs in cranial nerve motor nuclei
Face, jaw, tongue, and throat
What is the pathway of the rubrospinal tract?
Originate from nerve cells in red nucleus
Cross the midline of the midbrain and descends as rubrospinal tract (through pons and medulla)
Terminate in the ventral horn of gray matter
Facilitates the activity of flexor muscles (distal limb muscles)
What happens if there are corticospinal tract lesions?
Difficulty moving distal limbs
Loss of ability to make independent finger movements
What is the babinksi sign?
If you run a pen up someone foot the normal response is for the toes to flex down.
But if they have problem with upper motor neurons there toes will fan up when giving the same stimulus.
What is the vestibulospinal tract pathway?
For Balance
1. Begins in the vestibular nucleus in the medulla
2. Descends the vestibulospinal tract where it can be either coming from the left or right side of the spinal cord
What is the tectospinal tract pathway?
Orienting reflexes for the head
1. Begins in superior colliculus in the midbrain
2. Crosses the midbrain descends the tectospinal tract through the pons and medulla
3. Contralateral on the spinal cord’s ventral horn
What is the tectobulbar tract pathway?
Orienting reflexes for the eyes
What is the reticulospinal tract pathway?
For posture and locomotion
Pontine
1. Originates at the pontine reticular formation (pons)
2. Descends the medulla to the spinal cord in the intermediate gray matter
Medullary
1. Originates in medullary reticular formation (medulla)
2. Descends the reticulospinal tract to the intermediate gray matter
What activity happens in the primary motor cortex M1?
M1 neurons occur before and during a voluntary movement.
What are direction vectors?
Activity encodes force and direction of movement.
So when cell fires to leftward movement, direction vector points left
Length of vector corresponds to firing rate
Higher firing rate = more force
Points in the preferred direction for the neuron, but its length depends on the firing rate over a range of directions
What is a population vector?
Vector sum of direction vector of multiple cells
What is the Parietal-Tempora-Occipital Association cortex?
Proprioceptors- current position of body in space
Analysis of sensory inputs (vision, somatosensory, auditory)
Construct a representation of the world which sent to prefrontal cortex
What is the prefrontal cortex?
Executive function- working memory, reasoning, problem solving
Abstract thought
Decision making
Anticipating consequences of action
What are the supplementary motor area (SMA) and premotor area (PMA)?
Motor planning
What is the motor cortex, M1?
Initiation of complex voluntary movement
Origin of the corticospinal tract
What parts are in the basal ganglia?
Striatum: caudate/putamen
Globus pallidus
Subthalamic nucleus
Substantia nigra
