Neuro 4 - EMG

Question 1

What does an EMG do?

Answer 1

Records AP in skeletal muscle fibres

Two types:
Extracellular recording (surface EMG): 
Both electrodes outside muscle fibres
Record emf (voltage) between 2 points outside the cells

Intracellular recording (intramuscular EMG):
One electrode inside the cell
Measure emf (voltage) between inside and outside cell

Question 2

What is a twitch?

Answer 2

Basic response of a motor unit to a single stimulus

Question 3

Define tetany

Answer 3

If stimulus frequency is increased, individual twitches summate to cause sustained contraction

Question 4

Define summation

Answer 4

If second stimulus is applied before muscle fibre has relaxed, second twitch adds to remaining force