Pectoralis Major (Sternal Head)

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Other Names Chest Lower Pecs Heads Sternal Head (1 of 2 ) Also see Clavical Head Movement Shoulder Transverse Flexion Transverse Adduction Internal Rotation Adduction Extension Scapula (Assists) Downward Rotation Depression Abduction (initial) Attachments Origin Sternum (Anterior) Ribs (2 nd to 6 th) Costal Cartriges Insertion Humerus (Proximal Anterior) Intertubercular Groove (Outer Lip) Related Muscles Pectoralis Minor

Comments The sternal head of the pectoralis major is a stronger shoulder transverse flexor (shoulder internally rotated) than transverse adductor (shoulder externally rotated). It is a stronger shoulder adductor when the shoulder is internally rotated. It is also a stronger shoulder extensor when the shoulder is internally rotated. Incidentally, the sternal head of the pectoralis major does not extend the shoulder beyond anatomical position (shoulder hyperextension). The biarticulate sternal head of the pectoralis major enters passive insufficiency through the completion of shoulder transverse extension or transverse abducted when the shoulder girdle is more retracted or through the completion of shoulder abduction when the scapula is more rotated upward and elevated. The biarticulate sternal head of the pectoralis major enters active insufficiency through the completion of shoulder transverse flexion or transverse adduction when the shoulder girdle is more protracted or through the completion of shoulder adduction when the scapula is more rotated downward and depressed.