Name of lines drawn to indicate movement?

This is a bit of a cryptic one; I was wondering whether English has a word (or at least a phrase) to describe the lines typically drawn on a cartoon to indicate movement? A good example is the Windows XP 'Run' icon (in the top-left):

Solution 1:

Gesture lines can be used to indicate gestures, so I think that is a reasonable answer. I've seen motion lines more commonly used for the example that you have given.

Solution 2:

I don't have a good answer for you, but I've seen similar things referred to as gesture lines.

From Answers.com:

Gesture lines are lines that are energetic and catch the movements and gestures of an active figure.

Read more: http://wiki.answers.com/Q/What_is_a_gesture_line#ixzz1O1t4BWRg

Solution 3:

The word is called 'emanata' but only used in comic books though.