Motor Systems Flashcards
What does the primary motor cortex control?
Controls execution of movement.
The “on” switch
What does the supplementary motor area control?
- Coordination and execution of sequences of movement.
- Attainment of motor skills.
- Executive control of movement (how the movement is executed)
What does the premotor area control?
- Coordinates selection of appropriate motor plans for voluntary movements.
- lateral region = movements in response to external cues.
- medial region = movements in response to internal cues. - Mirror motor neurons
Where are mirror motor neurons located?
In the lateral premotor area.
- These neurons fire when watching someone else move.
What tracts are located in the lateral motor systems?
- Lateral corticospinal tract
2. Rubrospinal tract
What tracts are located in the medial motor systems?
- Anterior corticospinal tract
- Reticulospinal tract
- Tectospinal tract
- Vestibulospinal tracts
What does the lateral corticospinal tract control?
Movement of the extremities.
- Particularly important for rapid, dexterous movements at individual digits or joints.
- Modulatory control of myotactic reflex
What is the internal capsule?
Major highway for ascending and descending pathways.
What are the gray matter borders of the internal capsule?
Medial border = thalamus and caudate
Lateral border = globus pallidus and putamen
What are the components of the anterior limb of the internal capsule?
Thalamic and brainstem fibers that project to prefrontal and parietal cortical regions.
- Also associated with different aspects of emotion, motivation, cognition processing, and decision - making.
Where is the genu located in the internal capsule?
The middle portion between the anterior and posterior limbs.
What are the components of the posterior limb of the internal capsule?
- Descending motor fibers from frontal lobe going to brainstem and spinal cord.
- Ascending somatosensory fibers from spinal cord.
Somatotopically organized
Describe the somatotopic organization of the lateral corticospinal tract from lateral to medial in the subcortical regions.
Leg –> Trunk –> Arm –> Face (corticobulbar tract)
What does the anterior corticospinal tract control?
Controls bilateral axial and girdle muscles.
What percent of the corticospinal tract deccusates and what percent stays ipsilateral?
85% will deccusate and turn into the lateral corticospinal tract
15% remains ipsilateral to become anterior corticospinal tract
What does the rubrospinal tract control?
Controls movement of the extremities:
- Modulation of flexor muscle tone.
- Inhibition of anti-gravity muscles (extensors)
- Modulation of reflex activity (flexor withdrawal reflex)
What does the reticulospinal tract control?
Descending modulation from reticular formation that controls automatic posture and gait-related movements:
- Pontine reticular formation = inhibits limb flexors and excite extensors
- Medullary reticular formation = excite limb flexors and inhibit extensors.
What does the tectospinal tract control?
Controls coordination of head and eye movements.
- Effect head movements to match eye movements.
Where do multipolar alpha motor neurons exit the spinal cord?
Exit the spinal cord from the ventral horns, go through the ventral nerve root, and on to innervate target musculature.
Can peripheral nerves only travel solo or can they be found in plexi as well?
Found in both!
What is a myotome?
A group of muscles innervated by a single spinal nerve root.
What is the neuromuscular junction?
What is it essential for?
A highly specialized synapse between a motor neuron and its target muscle fiber.
Essential for muscle contraction and prevention of muscle atrophy.
What structures are found in the neuromuscular junction?
Synaptic bouton, synaptic cleft, and motor end plate.
How many neuromuscular junctions are there for each muscle fiber?
Just 1
