How to Identify the Pectoralis Major

The pectoralis major is a thick fan-like muscle at the upper anterior of the chest. It forms the majority of the chest muscle mass and is one of the most important muscles in body building. It is normally worked in compound movements such as the bench press but may be isolated with pectoral flies. The following steps will aid in your search for information about the pectoralis major.

Instructions

Difficulty: Easy

1. Read up on Latin roots to know that "pectoralis" means "chest" and "major" means "large." This is the larger chest muscle.
2. Examine the pectoralis major to see that it adducts the humerus and medially rotates the humerus. The clavicular portion also flexes the arm while it is extended.
3. Observe how the pectoralis major originates from the medial third of the clavicle, the anterior aspect of the manubrium, the length of the sternum, the cartilaginous attachments of the top six ribs and the external oblique's aponeurosis.
4. Look at the insertion of the pectoralis major into the lateral lip of the bicipital groove to the top of the greater tubercle. The clavicular fibers insert more distally and the sternal fibers insert more proximally.
5. Research the nervous system to know that the nerve for the pectoralis major is the lateral pectoral nerve from the fifth through seventh cervical nerves for the clavicular portion and the medial pectoral nerve from the eighth cervical and first thoracic nerves for the sternal portion.
6. Study the circulatory system to know that the blood supply for the pectoralis major is the pectoralis branch of the thoracoacromial artery for the clavicular portion and the lateral thoracic artery for the sternal portion.

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