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Pectoralis major muscle

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Attachments, innervation and functions of the pectoralis major muscle.
Pectoralis major muscle (Musculus pectoralis major)

The pectoralis major is a paired, superficial muscle located on the anterior surface of the thoracic cage. If you’re a gym lover, you’ll hear these muscles also being referred to as the pecs muscles. The pectoralis major has a broad origin, based on which it is divided into three parts: clavicular part, sternocostal part and abdominal part. All three parts converge laterally and insert onto the greater tubercle of humerus.

The main function of this chest muscle as a whole is the adduction and internal rotation of the arm in the shoulder joint. Acting independently, the clavicular part helps to flex the extended arm up to 90°, while the sternocostal part facilitates the extension of the flexed arm by pulling it downwards.

Key facts about the pectoralis major muscle
Origin Clavicular part: anterior surface of medial half of clavicle
Sternocostal part: anterior surface of sternum, Costal cartilages of ribs 1-6
Abdominal part: Anterior layer of rectus sheath
Insertion Crest of greater tubercle of humerus
Action Shoulder joint: Arm adduction, Arm internal rotation, Arm flexion (clavicular head), arm extension (sternocostal head);
Scapulothoracic joint: Draws scapula anteroinferiorly
Innervation Lateral and medial pectoral nerves (C5-T1)
Blood supply Pectoral branches of thoracoacromial artery, perforating branches of internal thoracic artery

In this article, we will discuss the anatomy and function of the pectoralis major muscle.

  1. Origin and insertion
  2. Relations 
  3. Innervation 
  4. Blood supply
  5. Function
  6. Correlaciones clínicas
    1. Poland syndrome
  7. Sources
+ Show all

Origin and insertion

The pectoralis major muscle is a fan-shaped muscle that consists of three parts that originate from three different sites: 

  • The clavicular part originates from the anterior surface of the medial half of the clavicle.
  • The sternocostal part originates from the anterior surface of sternum and the anterior aspects of the costal cartilages of ribs 1-6. 
  • The smallest, abdominal part originates from the anterior layer of the rectus sheath.

The muscle fibers from all three parts run laterally, converging towards the proximal humerus. They give off a broad tendon that inserts along the crest of the greater tubercle of humerus.

Feeling overwhelmed by so many muscle attachments? Check out our muscle anatomy reference charts to learn the anatomy of body's 800+ muscles faster!


The pectoralis major muscle is a broad superficial muscle found superficially in the anterior chest wall. In males, it is covered by the deep layer of fascia, subcutaneous tissue and the adjacent skin. In females, it is covered by the breast. The deep surface of the muscle covers the pectoralis minor and serratus anterior muscles and the anterior surface of the upper six ribs. 

The triangular depression between the pectoralis major muscle, deltoid muscle and clavicle is called infraclavicular fossa (Mohrenheim’s fossa) which serves as an important landmark in the surgical procedures on the subclavian artery.

To expand your knowledge check out our article about the main muscles of the thorax check out our other articles, videos, quizzes and labeled diagrams.


The pectoralis major muscle is innervated by the lateral and medial pectoral nerves (root value C5-T1), which stem from the brachial plexus.

Blood supply

The pectoralis major muscle is vascularized by the pectoral branches of thoracoacromial artery and the perforating branches of internal thoracic artery.


When the arm is in the anatomical position, the pectoralis major acts as a strong adductor and internal rotator of the humerus at the shoulder joint. Acting independently, the clavicular portion of the muscle flexes the humerus up to 90 degrees in a horizontal plane. The sternocostal portion of the muscle can produce the antagonistic movement and extend the humerus back to the anatomical position. 

Acting together with the latissimus dorsi muscle, the pectoralis major muscle pulls the trunk forwards or upwards when its humeral attachment is fixed. This action is important in activities such as climbing. When acting from the humeral attachment, the pectoralis major muscle also facilitates the act of inspiration. This is particularly important during forced breathing in physical distress.

Test your knowledge on the main muscles of the thorax with our quiz in multiple difficulty levels!

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