Muscle Function: Analysis and Demonstration Flashcards Preview

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Flashcards in Muscle Function: Analysis and Demonstration Deck (24)
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1

Agonist

Primary mover; responsible for the initiation and execution of a specific action at a joint

2

Antagonist

Opposes or reverses the action of the prime mover

3

Synergist

Assists the prime mover in its actions

4

Reciprocal inhibition

Skeletal muscles function in pairs; one of the muscles works as the agonist muscle and the other the antagonist

5

Electromyography

Analysis of motor unit action potentials (MUAP) and assessment of baseline electrical signal at rest

Recorded using a surface or needle electrode

Can be used to monitor a muscle's activity during a certain action and to assess integrity of the muscle and nerves supplying it

6

What is a motor unit?

All the muscle fibers innervated by one nerve

7

Innervation ratio

The number of muscle fibers innervated by a single axon/motor neuron

-Varies widely between muscle
-Low for fine motor (extra ocular muscles)
-High for gross motor (soles)

8

What are some of the different kinds of muscle action potentials?

Motor unit action potential
Sensory nerve action potential
Compound muscle action potential

9

What is the size principle?

Motor units are recruited from smallest to largest size.

10

How can electromyography be used to diagnose disease?

Tests skeletal muscle fibers
Standard needle electromyography mostly tests type I muscle fibers

11

How can Nerve conduction studies be used to diagnose disease?

Tests motor, sensory and mixed nerves

12

What are the three types of contraction?

Isometric
Concentric
Eccentric

13

Concentric contraction

Limb is shortening

14

Eccentric contraction

Limb is lengthening

15

Isometric contraction

No movement but still contracting

16

When you walk are there more eccentric or concentric contractions?

Eccentric

17

Name some agonists of wrist flexion.

Flexor carpi radialis
Flexor carpi ulnaris
Flexor digit profundus
Flexor digit sublimis

18

Name some antagonists of wrist flexion.

Extensor carpi radialis longus and brevis
Extensor ulnaris
Extensor digitorum

19

Name some agonists of hip flexion.

Iliopsoas
Rectus femoris
Add long/brev
Pectineus
Gracilis
Sartorius
Tensor fasciae latae

20

Name some antagonists of hip flexion.

Biceps femoris
Semitendinosus
Semimembranosus
Gluteus maximus
Adductor magnus

21

What is upper motor neuron syndrome?

Lesion of upper motor neuron in the CNS
Overactivity -- hyperreflexia, spasticity
Underactivity -- weakness
No inherent muscle atrophy

22

What is spasticity?

Velocity-dependent increase in tonic stretch reflex (muscle tone)

23

What can be used to reduce focal muscle overactivity?

Botulinum neurotoxin
Effects intrafusal and extrafusal muscle
May affect nociceptor pathways via C and A delta fibers and substance P
Can also be used to block salivary and sweat gland

24

Botulinum toxin mechanism of action

Heavy chain targets presynaptic membrane
Light chain goes in, gets endocytosed and cleaves SNAP-25
Local, temporary cholinergic chemodenervation