Flex Your Knowledge in 2026: Master Muscles, Actions, Origins & Insertions!

The clavicular head is part of the pectoralis major, so its origin is the medial half of the clavicle. This head and the sternocostal head together form the two-headed pectoralis major, with the clavicular portion starting on the inner half of the collarbone and the other portion beginning from the sternum and upper ribs. Knowing where a muscle head starts helps identify the muscle: if a head originates from the medial clavicle, it points to the clavicular head of pectoralis major. The other muscles listed have different origins—latissimus dorsi from the back and thoracolumbar fascia, serratus anterior from the upper ribs, and pectoralis minor from ribs and it attaches to the coracoid—so they don’t originate from the medial clavicle.