L9 Motor Neuron Flashcards
What is the Spinal Cord
A long fragile structure that begins at brainstem and continues down the spine.
Consists of nerves responsible for incoming and outgoing messages between the brain and body
Spinal Nerves
Emerge in two branches known as anterior and posterior root
Anterior Root
Carries motor signals from brain to peripheries
Posterior Root
Carries sensory signals from the peripheries to the brain
Cauda Equine
Spinal Cord tapers towards the end and carries impulses to and from the legs
What does the CNS control and what neurons does it consist of
Controls skeletal muscle and consists of UMN and LMN
Upper Motor Neuron
Originate in primary motor cortex and pass through the internal capsule .
In spinal cord they form the lateral corticospinal tract and synapse with LMN .
Axons of upper motor neurons make up the pyramidal tracts and decussate forming the pyramids
Lower Motor Neurons
cell body located in spinal cord
Axons emerge from anterior root and joins with sensory fibres and form mixed nerves.
What is a motor unit
The motor end plates of each nerve and uscle fibres they support form a motorunit
What is Motor Neuron Disease
A group of neurodegeneratice disorders that selectively affect motor neurons, the cells which control the voluntary movement of the body
How is MND classified
Inherited or Sporadic
Locus of degeneration
Amytrophic Lateral Sclerosis
Both upper and lower motor neurons
Most common form of MND
3-5 years
Primary Lateral Sclerosis (PLS )
Upper motor neurons only
Up to 20 years for patients who dont develop ALS
Progressive Muscular Atrophy
Lower Motor Neurons only
Variable evolution to ALS
5 years
Progressive Bulbar Palsy
Form of ALS, eventually develops ALS
Impacts speech and swallowing first
2-3 years
