To draw the arm, it's best if we have a brief understanding of the muscles at work. The Deltoid is the shoulder and it connects to the chest and back. I like to think of it as a puffy heart shape. The Bicep is usually an oval or rounded diamond. It stretches all the way down from the Deltoid to the fold in the arm. Now the Tricep is best thought of as a fortune cookie shape with elongated edges..