lumbar region has six and by the time the horse is five years old the sacral area’s five vertebrae have fused. The twenty caudal vertebrae round out the spine. I only gave you these numbers next because I want you to complete the skeleton by adding the ribs. The horse has eighteen ribs, one for each thoracic vertebra. In order to help you overcome any shyness you may have about your drawing let me show you what my horse looks like.

      Please forgive me for helping you discover your talent for drawing. If it were not so important to completely understand the functioning of this part of the horse’s anatomy, I would not have put you through this ordeal. I promised earlier that I would come back to the front legs. Yes they have joints and are not straight, but for the purpose of explaining in a short article the biomechanics of the horse, we must limit ourselves to the most important points of carriage and propulsion.

      In order to make this skeleton move we need to flesh it out with muscles. No, I am not going to ask you to draw them also, so please relax as you read on. The joints of the horse, in order to bend and stretch, are surrounded by at least two muscles that oppose each other. As one contracts, the other must stretch and vice versa. Take a weight of any kind into your hand and then open and close your elbow. Do it again and this time feel your biceps. Did you notice that even as you opened the elbow the biceps did not completely relax? It acted as a control to keep the lower arm from just falling back and thus hurting your elbow. Now take your arm and the weight behind you and open your elbow. With your arm in this position it is your triceps that have to work, and as you close the elbow again, it is this muscle that prevents your lower arm from just dropping down unless you consciously ask it to just let go. You can see the intricate coordination of these muscles necessary for smooth and controlled movement.

      The muscles on your arm that I described above are action muscles. They are strong and quick acting, but when asked to stay in one position, they fatigue quickly. The other type of muscle is the more static muscle that is interlaced and surrounded by tendinous tissue, which is one of the reasons that enable it to maintain a static position over a long period of time. The horse has both types of muscles and it has them exactly at the places needed so it can carry us.

      A picture is worth a thousand words. In order not to have to write a book, let us draw the most important muscles onto the skeleton of a horse. I would like to start with the head-neck-shoulder part first.

      Please realize that the horse has multiple layers of muscles over most of its body and I only want to show the main ones. By that I mean those muscles that most help me explain how correct training can turn a relatively weak back into a back strong enough to carry the additional burden of the rider and still remain supple. I sacrifice some scientific accuracy for simplification so that I can demonstrate that the ability to carry extra weight was built into the design of the horse.

      The drawing depicts the six main muscles of the neck and a ligament that Mother Nature uses to support the back (nuchal ligament). In order to simplify the writing and the reading of this portion of the article, I will name the muscles and tendons according to their function or their location.