The Motor System 1 Flashcards
What are the forms of activity?
Motor function
Sensory function
Sensory-motor integration
Cognition
What does the motor system involve mainly?
Movement within the body/ of parts of the body in space
What are the individual movements?
Limb Trunk Neck Facial Eye Tongue and throat
Describe the hierarchical plan of the motor system
UMN
LMN
NMJ
Muscle
Describe an upper motor neurone
Cell body in the brain
Control Lower motor neurons
Describe a lower motor neurone
Cell body in motor nuclei of brainstem (if controlling head and neck- cranial nerves) or spinal cord in the anterior horn (CNS)
Control muscles
What are the types of muscles/ where they are in the body?
Limb
Truncal
Bulbar- face and head
How do we control muscle movement?
Organise the muscles into agonist and antagonist muscles
What type of organisation does muscles working in groups reflect?
Neural
What does a LMN typically control?
A focal anatomically adjacent group of muscle fibres
How does UMN and LMN differ in action on muscles in terms of organisation?
UMN= groups of muscles LMN= individual muscles movements
What are the functional motor components of muscles?
Muscle fibres
Where do the lower motor neurone axons terminate?
In the muscles to control the muscles
What do motor end-plates (myoneural junctions) consist of?
Motor nerve fibre ending and the subjacent part of the muscle fibre
What is the neurotransmitter used in NMJ?
ACh
Which motor neuron cords from the spinal cord control which body parts?
Cervical cord= arms
Thoracic cord= trunk
Lumbosacral cord= legs
How are bulbar muscles supplied?
Cell bodies in brain stem nuclei axons travel in cranial nerves to supply bulbar muscles
How do axons of spinal cord LMNs pass out?
Nerve roots and periphery nerves
What is the gross anatomy of the peripheral nerve?
Motor neuron and sensory neuron, nerve fibre (axons), endoneurium (connective tissue around the myelin sheath of each myelinated nerve fiber) in nerve trunk
What is the motor unit?
A motor neurone and the muscle fibres supplied by that neurone
Number of muscle fibres in a motor unit varies from 1-100s depending on the need for precision in movement
How are limb muscles supplied?
Cell bodies in spinal cord grey matter axons travel in roots/ periphery nerves
How are truncal muscles supplied?
Cell bodies in spinal cord grey matter axons travel in roots/ thoracic nerves
What are the causes of systemic muscle disease?
Genetic
Metabolic
Autoimmune
What does weakness tend to be?
Generalised
Symmetrical
Proximal
Where may LMN disease be?
Spinal cord
Spinal root and nerves
Brain stem
Cranial nerves
What are the most clinically important nerve roots?
Upper limb= C5, 6, 7
Lower limb= L5
Degenerative disease, disc prolapse common
What are the clinically important motor nerves in the upper limb?
Median
Ulnar
Radial
What are the clinically important motor nerves in the lower limb?
Sciatic Common peroneal (around fibula head)
What is polyneuropathy?
All of the axons in peripheral nerves are affected
