Muscular Problems & Neuromuscular Junction Flashcards
What are the properties of a muscle affected by LMN disorders?
- Weak
- Has low tone
- Has fasiculations
What are fasiculations?
- Visible, fast, spontaneous twitches occurring in denervated muscle
- May occur in healthy muscle
- A sign of motor neurone disease
What is the three step process to make muscles contract?
Motor neurone - Neuromuscular junction - Muscle
Where do lower motor neurone cell bodies arise?
Ventral horn of the spinal cord
What is the definition of a motor end plate?
The synapse formed between motor neurons and muscles
What substance is toxic IV/IM because it occupies the same position on ACh receptors but does not open the ion channels?
Curare
What does botulinum toxin do?
Cleaves presynaptic proteins involved in vesicle formation and blocks docking with presynaptic membranes
What occurs in Lambert Eaton Myasthenic syndrome?
Auto-antibodies to presynaptic calcium channels leads to decreased vesicle release
What occurs in Myasthenia Gravis?
Autoimmune reaction to acetylcholine receptors which leads to muscle weakness and fatiguability (when ACh receptors reduced to
What also plays a role in MG?
The thymus - 75% of patients have hyperplasia or thymoma
How is MG treated?
- Acetylcholinesterase inhibitor (pyridostigmine)
- Thymectomy
- Steroids
What is myotonia?
Failure of muscle to relax following use
