big guns: the muscular system - crashcourse biology #31 Published 12 years ago • 1.6M plays • Length 12:52 Download video MP4 Download video MP3 Similar videos 10:24 muscles, part 1 - muscle cells: crash course anatomy & physiology #21 5:51 the muscular system explained in 6 minutes 4:26 how your muscles work 3:03 the musculoskeletal system | educational videos for kids