Pectoralis major muscle

Pectoralis Major Muscle

The Pectoralis Major Muscle (pronounced: pek-to-ral-is may-jor mus-ul) is a thick, fan-shaped muscle, situated at the chest (anterior) of the human body. It makes up the bulk of the chest muscles and lies under the Breast.

Etymology

The term "Pectoralis Major" is derived from the Latin words 'pectus' which means 'breast' and 'major' meaning 'greater'. It is named so due to its larger size compared to the Pectoralis Minor, the other muscle in the pectoral region.

Anatomy

The Pectoralis Major Muscle originates from the clavicle (collar bone), the sternum (breast bone), the ribs, and the Fascia (a band of connective tissue) over the abdominal muscles. It has two parts: the clavicular part and the sternocostal part. The muscle fibers converge towards the insertion point, forming a flat tendon that attaches to the Humerus (the bone of the upper arm or forelimb).

Function

The Pectoralis Major Muscle is primarily used for movement of the Shoulder Joint. The actions of the Pectoralis Major include flexion, adduction, and medial rotation of the humerus. It plays a vital role in activities that require pushing and pressing.

Related Terms

Pectoralis Minor: A thin, triangular muscle, situated beneath the Pectoralis Major.
Serratus Anterior: A muscle that lies deep to the Pectoralis Major on the lateral chest.
Deltoid: A large triangular muscle covering the joint of the shoulder, and serving to raise the arm laterally.
Latissimus Dorsi: A broad, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline.