Motor Function Flashcards
What are alpha motoneurons?
Final neurons located in the ventral horn of the spinal cord.
What is a motor unit?
Smallest functional unit of movement. Has a motoneuron, axon and all muscle fibres innervated by this neuron.
What is the sequence of events in a neuromuscular junction?
- Arrival of AP
- Ca channels open and Ca enters
- ACh exocytosed and released to synapse
- Action of ACh
- ACh reuptake.
Function of a motor end plate
Increases SA at the junction
What is the function of ACh at the neuromuscular junction?
Opens ACh receptor ion channel and allows Na through, causing depolarisation and AP in the post-synaptic cell.
What is tetany?
A temporal summation causing a steady-state contractile force in response to repeated APs.
What 2 substances block ACh receptors and release, respectively?
Curare and botulinium toxin
What 2 substances are cholinesterase inhibitors?
Physostigmine and organophosphates
What causes a reflex?
Sudden stretch of the intrafusal muscle spindle. Performed in a predictable manner without conscious control.
Function of primary motor cortex?
AKA M1, area 4
Functions to send signals for motor movements on the contralateral side
What symptoms do we see in cord transection AKA Brown-Sequard syndrome?
Contralateral pain and temperature loss, ipsilateral loss of proprioceptive and tactile senses, paralysis
All below level of the lesion.
Upper motor neuron damage (voluntary control, muscular atrophy, tone and reflexes)
Voluntary control reduced or absent
No atrophy
Increased muscle tone (spasticity)
Hyperreflexia
Lower motor neuron damage (voluntary control, muscular atrophy, tone and reflexes)
Voluntary control reduced or absent
Atrophy present
Reduced tone
Reduced or absent reflexes.
