The pectoral muscles are divided into two groups:

1. Own muscles of the chest (internal and external, as well as the diaphragm). These muscles fill the intercostal spaces.
2. Muscles related to the shoulder girdle and upper limb (these are pectoralis major and minor, subclavian and serratus anterior).

* The pectoralis major muscle is massive, fan-shaped, and occupies a significant part of the anterior chest wall. Its main function is to lower the raised arm and bring it to the body, while turning it inward. The pectoralis major muscles are flat paired muscles, and are the most adapted to growth (hypertrophy).

* The pectoralis minor, on the contrary, is flat, has a triangular shape, and is located under the pectoralis major muscle. Its 4 teeth start from the 2nd to the 5th ribs, and are attached to the shoulder blade. Its main function is to pull the scapula forward, inward and down, and with a fixed scapula, it raises the ribs.

* The subclavian muscle is located between the upper rib and the collarbone. Its main function is to move the collarbone down and inwards; strengthening the sternoclavicular joint. And with a fixed shoulder girdle, it raises the first rib.

* The serratus anterior is a broad, flat muscle that is located on the lateral surface of the chest muscles. It starts with teeth from the upper ribs and is attached to the medial edge of the scapula. Main function: to pull the scapula forward and outward, turning it, and also participates in the rotation of the scapula when raising the arm to a vertical position.

* Intercostal muscles (that is, external and internal) – originate from different edges of the ribs and participate in the process of inhalation – exhalation.
* Subcostal muscles – located on the inner surface of the lower ribs. They differ from the intercostal muscles in that their bundles are thrown over one rib. Its main function is participation in the act of exhalation.

* The diaphragm is the main respiratory muscle, which is a movable muscular-tendon septum between the chest and abdominal cavities. During contraction, the diaphragm moves away from the walls of the chest cavity, its dome flattens, which leads to an increase in the chest cavity and a decrease in the abdominal cavity, and inhalation occurs. With simultaneous contraction with the abdominal muscles, the diaphragm contributes to an increase in intra-abdominal pressure, which is critical when working with large weights.