Pectoralis Major

Joe Muscolino

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The pectoralis major has two heads: sternocostal head and clavicular head. The deltoid has been ghosted in.The Pectoralis Major is composed of two heads: Sternocostal head and Clavicular head.

ATTACHMENTS:

  • The pectoralis major attaches from the medial clavicle, sternum, and the costal cartilages of ribs #1-7 to the lateral lip of the bicipital groove of the humerus.

 

ACTIONS:

  • Adducts the arm at the glenohumeral joint (entire muscle)
  • Medially rotates the arm at the glenohumeral joint (entire muscle)
  • Flexes the arm at the glenohumeral joint (clavicular head)
  • Extends the arm at the glenohumeral joint (sternocostal head – from a position that is flexed beyond anatomic position)
  • Horizontally flexes the arm at the glenohumeral joint (entire muscle)
  • Protracts the shoulder girdle (acting through the humeral attachment) at the scapulocostal joint and sternoclavicular joints (entire muscle)

 

NOTES:

  • The pectoralis major comprises the vast majority of the anterior axillary fold of tissue.
  • There is a twist in the fibers of the sternocostal head of the pectoralis major.