You can assume that each muscle has a number of parts equal to the name. Biceps has "bi" which is equal to 2 and so the biceps has a short head and long head to make up the biceps muscle. The triceps has 3 heads, the long head, medial head and the lateral head. The quadriceps has 4 components, the vastus medialis, vastus intermedius, vastus lateralis and the rectus femoris.