Motor Systems Flashcards
What is the function of the Primary Motor Cortex
Controls execution of movement
What is the function of the supplementary motor area
Coordination and execution of sequences of movement, attainment of motor skills
Receives info from cerebellum and basal ganglia
What is the function of the premotor area
Coordinates selection of appropriate motor plans for voluntary movements
Help execute motor function
“Picks motor plan from experiences or motor memory”
What are 2 systems in descending motor tracts?
Lateral and Medial Motor Systems
What are the tracts in the lateral Motor Systems
Lateral Corticospinal Tract
Rubrospinal Tract
What are the tracts in the Medial Motor Systems
Anterior Corticospinal Tract
Reticulospinal Tract
Tectospinal Tract
Vestibulospinal Tract
What does the Lateral Corticospinal Tract control
Controls movements of extremities
-particularly important for rapid, dexterous movements at individual digits or joints
What is unique about the internal capsule
Somatotopically organized
What does the Anterior Corticospinal Tract control?
Controls bilateral axial and girdle muscles
What does the Rubrospinal Tract control?
Controls movements fo 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
Automatic posture and gait related movements
- pontine: inhibit limb flexors and excite extensors
- medullary: excite limb flexors and inhibit extensors
What does the tectospinal tract control
Controls coordination of head and eye movements
-effect: head movement to match eye movements
What are the 3 major plexi that we can find peripheral nerves?
Cervical Plexus C3-C5
- Diaphragm innervation
Brachial Plexus (C5-T1) -UE innervation
Lumbosacral Plexus (L1-S4) -LE innervation
What is a myotome
Group of muscles innervated by a single spinal nerve
What is a neuromuscular junction and why are they important
Highly specialized synapse between a motor neuron and its target muscle fiber
Important because it is essential for muscle contraction and prevention of muscle atrophy
How many NMJ for each muscle fiber
1
What are the synaptic boutons
Terminal axons of motor neuron
What is the motor end plate in a NMJ
- Area that falls under synaptic boutons
- junctions folds
- AcH ligand gated synaptic boutons
Explain the NMJ synapse
AP form presynaptic motor neuron triggers release of ACh into synaptic cleft
AcH binds to ACh receptors, which open to allow Na to flow into muscle fiber — > leads ESPS —> AP travels down muscle fiber to facilitate contractions —> Acetylcholinesterase breaks down Ah to end contraction
Describe Type Ia (type, location and function)
Slow Motor Unit
Smaller muscles
Sustained muscle contractions
Describe Type IIa (type, location and function)
Fast fatigue - resistant Motor Units
Intermediate in size
Generate 2x force as slow, and better resistant to fatigue than FF
Describe Type IIb (type, location and function)
Large muscles
Brief, but forceful contractions
What is the size principle in regards to the Motor Unit
Regulation of muscle force
Weak synaptic stimulation recruits smallest motor units
As inputs increases, progressively larger motor units are activated —> larger forces generated
What is the order of the muscle fiber recruitment
Slow —> Fast Fatigue- resistant —> Fast Fatigable
