The Triceps Muscle is the “three headed” (tri-cep) muscle on the back of the upper arm, opposite the bicep. I honestly do not see much Triceps Tendinosis, but when I do, it’s usually in a weightlifter that has gone a bit overboard. I rarely see the problem develop at the top of the muscle (near the shoulder). If it is going to occur, it will happen just above the back of the elbow. However, when it does develop, Triceps Tendinosis can be quite severe. For those of you wondering why the name Triceps Tendinosis instead of the more commonly used, Triceps Tendinitis, you need to spend a few minutes on our TENDINITIS OR TENDINOSIS page.