<span>Isometric muscular contractions do not change the length of the muscle they are responsible for movement. Isotonic muscular contractions will lengthen or shorten the muscle. Concentric contractions shorten the muscle. Eccentric contractions lengthen the muscle.</span>
The pectoralis major muscle can be divided into groups of
fibers superior, or claviclular, and inferior, or sternocostal.
<span>Pectoralis is a major muscle fundamentally responsible for
shoulder joint movements. It is divided
into four actions and two groups of fibers, anatomically the superior side and
interior side. These movements are often
used in everyday lives like throwing and flapping the arms.</span>
