The structures at the bottom of this image that look like scales are actually bundles of muscles just under the skin of a rabbit. This image is a stained cross section taken under polarized light ...

A trigger point is an area of muscle that causes referred pain. It may twitch, and you may feel a knot or tightness under the skin. A trigger point is not the same as a tender spot.

This simple exercise for bat wing arms takes just a few minutes each day and you don't need any fancy gym equipment to do it ...