If you look on the bottom of a rattlesnake, there are scales that are wider than normal scales, and they start at the top and go down to the bottom. These scales are called scutes(below). Snakes have a very complex muscle system that use these scutes into their movement. They have literally hundreds of ribs, each with its own muscles. So these scute have its own set of ribs, that have its own muscles, and there are hundreds of scutes. Since there are so many separate muscles, and ribs, they are able to lift up portons of the body.They have one pair of ribs for every scute. These ribs can move individually and can therefore control the scute below. To put it simply, they use their ribs to move these scutes, which push back on the ground, thus moving them forward. It is a very differenr, yet very efficient, form of movement.
Eastern Diamondback Rattlesnake
The muscular system of an eastern diamondback rattlesnake