Clavicular portion - flexion, horizontal adduction, inward rotation; abduction when arm is above 90 degrees.
Sternal portion - adduction, inward rotation, and horizontal adduction; extends to AP position.
Pectoralis Major
Origin = Two Origins
Clavicular portion - medial 2/3 of the clavicle.
Sternal portion - anterior portion of the sternum, and cartilages of the first six ribs.
Insertion = Lateral aspect of the humerus just below the head.
Action = Two Actions
Clavicular portion - flexion, horizontal adduction, inward rotation; abduction when arm is above 90 degrees.
Sternal portion - adduction, inward rotation, and horizontal adduction; extends to AP position.