The Anatomy of the Chest Muscles

Introduction

It’s no secret that almost every single lifter out there places their chest development at the top on their list of priorities. The pectorals, or chest muscles, are so large and prominent that they can’t be hidden. A massive chest anchors the upper body and enhances the appearance of your shoulders, arms, and abs. Most people enjoy working the chest, because they can easily see and feel the muscles as they lift and enjoy the pump.

Keep your chest development in proportion to the rest of your body. Some bodybuilders get fixated on having a huge chest. They do bench press over and over, at the expense of exercises for other muscles. The result is an unbalanced physique. It looks somewhat ridiculous to have a bowed-out chest and bird-like arms and legs.

Chest Muscles Anatomy

The chest is made up primarily of two muscles: (1) the pectoralis major, and (2) the pectoralis minor.

(1) Pectoralis Major Muscle

The pectoralis major is the large superficial chest muscle that pops when you wear a tight T-shirt. It spreads out like a fan and covers the rib cage like an armor plate.

The pectoralis major has two anatomic sections or heads:

• (a) the upper pectoralis major (upper clavicular head) – arises from the clavicle (collarbone).
• (b) the lower pectoralis major (lower sternal head) – arises from the sternum (breastbone).

The two heads pass outward across the chest wall and merge into a single tendon that attaches to the humerus bone in the upper arm.

The pectoralis major originates at the anterior surface of the rib cage and inserts at the anterior surface of the upper end of the humerus.

It is a powerful muscle whose main function is to bring the arms together in front of the rib cage. It is also known as the hugging muscle. In other words, pectoralis major adducts, flexes, and internally rotates the arm, thus moving the arm forward and across the chest during movements such as bench press or dumbbell fly.

Even though the muscle has only two anatomic divisions, functionally it may be considered in three sections (upper, middle, and lower) depending on the angle through which the arm is moved.

The middle section is the largest, and it is targeted when your arms work at a 90-degree angle to your body, as in horizontal adduction. The upper chest  is worked when the exercise is performed on an incline, such as an incline press or incline dumbbell fly. You want your arms to extend at about a 45-degree angle to your body, or about eye level if you are standing. The lower chest is the smallest section of the pecs, and it is emphasized by performing decline actions. The hands should finish down low close to the hips to target this area of the pecs.

(2) Pectoralis Minor Muscle

The pectoralis minor is a smaller muscle that lies underneath the pectoralis major muscle and it is not visible. It is also an upper chest muscle that originates on the third, fourth, or fifth ribs (depending on the man), and inserts on the scapula. Its main job is to lift the ribs. When you take a deep breath and your chest rises, that’s the pectoralis minor at work.

Chest Exercises

The first order of importance when it comes to chest training is to ensure that you include exercises that target the upper, middle, and lower pectoralis.

The chest exercises are divided into barbell pressing exercises, dumbbell pressing exercises, machine pressing exercises, fly-type exercises, and push-up and dip exercises.

Basic, multi-joint exercises for the chest involve pressing movements, such as barbell press, dumbbell press, and machine press performed on a flat, incline or decline bench. Presses are considered compound movements because both the shoulder and elbow joints are initiating the movement. Push-ups and dips are also considered a pressing exercises.

Isolation exercises for the chest are fly-like exercise that involve movement of the arms without any change occurring at the elbow joint. They isolate the pectoral muscles with minimal involvement from the triceps. Examples of the isolation exercises for the chest include the dumbbell fly, cable crossover, and pec-deck.

Closing Thoughts

Chest muscles are responsible for adduction, internal rotation, and forwards flexion of the humerus. This muscle group is responsible for “pushing” movements and interacts synergistically with the anterior deltoid of the shoulder and triceps of the arm.

The pectoralis major is one of the most striking muscles in the human body, to such an extent in fact that it is often overtrained compared to the back muscles. Combined with overtraining of the abdomen (no less common), this can eventually produce a kyphotic posture (i.e., outward curvature of the spinal column in the thoracic region, causing a rounded back). This problem is easily prevented by training the whole body harmoniously and regular stretching.