Origin:

  • Spinous process of the vertebrae T6-T12
  • Thoracolumbar Fascia
  • Iliac crest
  • Lower ribs (inferior 3rd and 4th)

Insertion: Inter-tubercular groove of the humerus

Action:

  • Extension of the Humerus (arms straight or bent)
  • Antagonist with Pec Major when medially rotated and adduction of the humerus and also in depression of the scapula (i.e upward motion of push ups.
  • Synergist with Pec minor in depression of Scapula

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