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Describe the difference between muscle tension, muscle contraction and a muscle twitch. (5 pts.)

A muscle twitch is the response of a muscle to a single action potential of its motor neuron. The fibers contract quickly and then relax.

Twitch contraction of some muscles (extraocular) are rapid and brief, others (gastrocnemius, soleus) are slower and longer.

The force exerted on an object by a contracting muscle is called muscle tension, the opposing force or
weight of the object to be moved is called the load.

Two types of Muscle Contraction:

• When muscle tension develops, but the load is not moved (muscle does not shorten) the contraction is
  called Isometric.
• If muscle tension overcomes (moves) the load and the muscle shortens, the contraction is called Isotonic