In her new book, “On Muscle,” Bonnie Tsui investigates the other stuff our thews remember—like how to grow when you exercise.

And yet, its humerus (an arm bone) is quite human-like ... a "sagittal crest" (a ridge running from front to back on the top of the skull) from which muscles running to the jaw were attached.

Part two of two teaching films about human anatomy which is devoted to the action of the skeletal muscles in producing movement of the bones at the joints of the human skeleton. It uses live ...