Muscle function

Question 1

3 movement muscle types

Answer 1

agonist (primary mover), antagonist, synergists

Question 2

Reciprocal Inhibition

Answer 2

agonist is stimulated and antagonist is inhibited;

this allows for max efficiency, speed, and control

Question 3

In neurologically intact patients, which group mediated reciprocal inhibition contributes to antagonist suppression during movement?

Answer 3

group Ia

Question 4

Electromyography

• What is it
• What is it used for?
• what kinds of nerves does it test for?
• What kind of fibers does it primarily test for?

Answer 4

depolarization of a motor unit creates a motor unit action potential (MUAP)–look for size, complexity, and firing frequency

• can be used to monitor muscle activity during action to assess the integrity of the muscle/ and peripheral nerve system; (nerve compression, hereditary/acquired disease, myopathy…)
• can test for motor, sensory, and mixed nerves
• EMG mostly tests for type I muscle fibers

Question 5

Components of a motor unit (4)

Answer 5

neuron cell body located in anterior horn, axon, NMJ, and muscle fibers

Question 6

Innervation Ratio

Answer 6

of muscle fibers innervated by a single axon/motor neuron

-low for fine motor; high for gross motor.

Question 7

Sensory nerve AP vs motor nerve AP

Answer 7

See slides

Question 8

Size Principle muscle action

Answer 8

small motor units/fibers are activated first… they increase in firing frequency and at the same time larger motor units are recruited…so on.

Question 9

3 types of skeletal muscle contractions

Answer 9

1. Concentric: contracting
2. Eccentric: extending (muscles generally spend more time in eccentric contractions)
3. Isometric: no movement but still contracting/bearing weight

Question 10

Upper motor neuron Syndrome

• Where is lesion?
• Symptoms?

Answer 10

lesion of the upper motor neuron in the CNS (brain/spinal cord) leading to
overactivation (positive signs): hyperreflexia; spasticity
underactivity (negative signs): weakness

NO ATROPHY!!!

Question 11

Spasticity

• what is it?
• How can you treat it clinically?

Answer 11

“velocity dependent increase in tonic strech reflex (muscle tone)
hyerpexcitability of stretch reflex
-Treat with Botulinum toxin

Question 12

Botulinum Neurotoxin
Which types of muscle fibers does it affect?
Which Nociceptors and substances are affected other than muscle fibers?
Can be used to treat what?

Answer 12

• affects both intrafusal and extrafusal fibers
• affects both Adelta and C pain fibers; also substance P…therefore decreases pain in general
• use to: block sweat/salivary glands; spasticity, dystonia, ophthalmologic/dermatologic pain, GI/GU.

Question 13

Botulnum toxin

Mechanism of action

Answer 13

has heavy and light chain. Heavy chain binds neuron, and light chain enters into cytoplasm. Light chain cleaves SNP25, so that Ach vesicles cannot dock on and be released.

Question 14

What does needle EMG test for?

Answer 14

Type I muscle fibers

Question 15

Synovial Joints

• Structure
• movements involving synovial joints
• Types of synovial joints

Answer 15

• cavity between joings. Fibrous capsule that’s lined with synovial membrane that secretes viscous fluid
• allows for gliding, angular, and rotational movements.
• Gliding, hinge, pivot, saddle, Elipsoidal, ball-and-socket

Question 16

Clinical assessment of muscle function (3) methods?

Answer 16

manual muscle testing; motion analysis; electromyography