The chest is comprised of two primary muscles groups – the pectoralis major and pectoralis minor – and one minor muscle, the serratus anterior. All of these muscles, except the serratus anterior, connect the bones of the chest at various points to the shoulder and arms.
This fan-shaped muscle covers much of the chest area and divides into three separate heads – the sternocostal, abdominal and clavicular. However all the heads connect to the humerus on one end.
Sternocostal – The sternocostal head connects midline of the chest at the breastbone and cartilage running to the ribs (at the second to the sixth).
Abdominal – Sitting under the sternocostal, this head attaches to the breastbone and the second to sixth rib cartilage also.
Clavicular – Sitting on top of the sternocostal, it connects at the collarbone instead of the breastbone.
All three heads have the exact same function – allowing us to move our arms across our body.
Smaller than the major, it sits just underneath it and connects to the shoulder blade on one end and from the third through the fifth ribs on the other end. The minor allows the shoulder to move down and forward and is the opposing muscle group of the trapezius.
Connecting the shoulder blade to the upper eight ribs, these muscles runs down the side of the body almost across the whole width of the shoulder blades. They allow the shoulder blades to thrust forward as when pushing something. They are also used in breathing: flexing on the inhale, contracting on the exhale.
Building Chest Muscle
Here are some exercises that target each of the chest muscle groups:
Pectoralis (both major and minor) – incline barbell, dumbbell bench press and incline dumbbell flyes (all done at a 30 to 45% incline), decline barbell, dumbbell bench press and decline dumbbell flyes (all done at a 30 to 45% decline).
Serratus Anterior – Do shoulder blade protractions. Lean against a wall and press the backs of your palms and your elbows against it. Then slide your shoulder blades forward (away from each other) – keep them down as well – and hold.
The muscles of the chest mainly allow us to move our arms multi-dimensionally and to push things forward. As with other groups of muscle, be sure to work each one equally. Not only will it give you a more balanced look, it will reduce the risk of an injury. With these muscles, an injury will most likely hurt every time you breathe until healed.