The word “muscle” comes from the the Latin mus (mouse) and cul (a diminutive suffix).  So a muscle was the little mouse that crawls beneath your skin when you flex.  Those old Romans must have been weak.  A mouse?  Really?  I call my guns the “caniscles,” from the Latin canis (dog).  Yeah, that’s right.  When I flex, a little dog runs up my arms under my skin…