What are pectorales majors?

Pectoralis major is a large, fan-shaped chest muscle. It originates (begins) from the sternum (breastbone) and costal cartilage (the cartilages that connect the ribs to the sternum), and inserts (ends) onto the upper arm bone (humerus). The pectoralis major is responsible for several movements of the arm, including flexion (bending), adduction (moving towards the midline), and internal rotation (turning inward).

There are three major muscle groups that make up the chest: the pectoralis major, pectoralis minor, and serratus anterior.

The pectoralis major is the largest and most superficial chest muscle.

- It originates from the sternum, clavicle (collarbone), and upper ribs.

- It inserts onto the upper arm bone (humerus).

- The pectoralis major is responsible for several movements of the shoulder joint, including flexion (bringing the arm forward), adduction (moving the arm toward the body), and internal rotation (turning the arm inward).

The pectoralis minor is a smaller, deeper chest muscle that lies beneath the pectoralis major.

- It originates from the third, fourth, and fifth ribs.

- It inserts onto the coracoid process, a small bone on the upper arm.

- The pectoralis minor assists in drawing the shoulder blades together and depressing the shoulder.

The serratus anterior is a thin, fan-shaped muscle that lies on the side of the chest.

- It originates from the first nine upper ribs.

- It inserts onto the inside surface of the shoulder blade (scapula).

- The serratus anterior is responsible for protracting (moving forward), elevating, and rotating the shoulder blade.