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Makedah,
The "upper pecs" is the Pectoralis Major, and it has a clavicular head and a sternal head. In other words there are two origins (sternum and ribs) and one insertion, the humerus.
As for function, 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.
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 pectoralis minor starts at the ribs and inserts at the scapula. It functions in abduction, downward rotation, and depression of the scapula.
I have no idea what people call the "lower pec." Probably the same thing people call the "lower abs." There is no "lower ab" except in exercise fairy tale land.
The "upper pecs" is the Pectoralis Major, and it has a clavicular head and a sternal head. In other words there are two origins (sternum and ribs) and one insertion, the humerus.
As for function, 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.
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 pectoralis minor starts at the ribs and inserts at the scapula. It functions in abduction, downward rotation, and depression of the scapula.
I have no idea what people call the "lower pec." Probably the same thing people call the "lower abs." There is no "lower ab" except in exercise fairy tale land.
