Harmony Of Structure & Function: The Pecs.

Understanding the link between the structure and function of a particular muscle will help you to make the right decision, put together an intelligent program and start adding some high quality muscle mass.

Note: Click Here To Read 'The Lats'.

Of all the various muscle groups that make up the human body, the chest is one of them that seem to consume more bodybuilders than any other. People come to me asking how they can work the upper chest, the lower chest, the inner chest, the outer chest, the upper middle and the lower outer. It is down right perplexing and most of all, absurd. Building a thickly muscled, well developed chest is not that complex. It may not happen as quickly for some compared to others, but it certainly is not difficult. In fact, once we take a look at the structure of the pectoral group, you will see that training this group is very easy to do.


The primary component of the chest is the large muscle named Pectoralis Major. It is only one muscle of many that is used to move the shoulder girdle and manipulate the arm (above the elbow). All of the muscle fibers that make up the Pectoralis Major run from the sternum and the sternal ends of the first 7 ribs, all the way to a small bump on side of your humerus bone call the greater tubercle. If you recall from the first installment of Structure and Function about the lats, this is almost the same exact point of where our lats attach to our arm.

As a matter of fact, the fibers that attach to the arm run over the fibers of the lattissimus muscle. All of the fibers run in one direction. It is a one way, non-stop flight from the sternum to the humerus There are no facsial divisions or tendons that would constitute the distinction of a inner or outer chest. The Pectoralis major is all one piece in a sense. There is no reason to try to find exercise that will increase the size of the inner aspect more than the outer because there aren't any exercises that can do that.

An easy way to think of this is to find a rubber band and place it between the thumb and index finger of one hand. Let's imagine that your thumb is your sternum making the part of the rubber band closest to your thumb the "Inner Chest". With that said, you can not move your thumb. Now, by only moving your index finger, I want you to try to stretch out only the part closest to your thumb. It's impossible. The entire band is going to stretch. And that is exactly how your pecs operate.

There is also a small gathering of gathering of muscle that lie underneath the Pectoralis major, that are collectively called the Pectoralis Minor. It starts from the middle of ribs 3-5 and attaches to the coracoid process that comes off of the scapula. That's because of its primary function it goes from the bottom up. Its primary function is only to depress the shoulder girdle.

This means if you to support your self on something with our your feet on the floor with your elbows locked out, the pec minor would be a player in forcing your shoulders down rather than letting them pinch your head off. It is also involved in raising ribs 3-5. In other words, when you take a deep breath and your rib cage expands. Since it does not attach to the humerus, it does not have any involvement in actually moving the arm. Keep that in mind the next time you hit the gym.


Now that we have a better understanding of what makes up the 'Chest' we can get into what the chest actually does for us. Going back the Pectoralis Major, By definition, it flexes, Adducts and medially rotates the arm (above the elbow). Flexing the arm mean that if your were to let your arm hang at your side, your chest would help you to raise it as if your were reaching for a door knob. Adduction means to bring back. So if your arms were being held up like you were being crucified, the Pectoralis major would help you to forcefully bring your arm back to your side.

Medial rotation is a fancy way or saying turning your arm in towards your body in a way that your elbows flare out to the sides. There is also Horizontal adduction. Which is much like regular adduction, however your arms are moving in a horizontal plane rather than a vertical one. So, clapping like a seal is horizontal adduction. And we have already talked about what the Pectoralis Minor does for us. So now lets move on to some of the exercises that are most effective for these muscles in terms of adding dense muscle mass.


Now that we know how the muscle of the chest are put together and what it is they do for us in terms of movement, we can weed through the smoke and mirrors and pick out the most effective exercise. The first exercise on the list is the king of chest exercises, the flat barbell bench press. This exercise is a adduction/horizontal adduction movement and by far the strongest movement that the Pectoralis Major can do.

Now when look at this exercise, it is very important to only look at the arm in terms of from the elbow up. What happens below the elbow has no bearing on the muscle of the chest. The flat barbell bench press is the best overall chest exercise because it allows you to handle great amounts of weight. This is the critical factor when trying to put on as much muscle in the shortest amount of time possible.

The next exercise on the list would be weighted dips. I know what you are thinking. This is a triceps exercise, right? Well yes and no. Remember, one of the primary functions of the chest was flexion of the arm. During the Dip exercise, our arms is in full extension at the bottom of the exercise. Forget about what is going on below the elbow. The arm is in full extension. From a forced extension, your chest is the workhorse that has to bring it back into the neutral position be flexing the arm. Yes, the triceps are involved, but the chest is the dominating muscle group here. By leaning your torso forward about 15-20 degrees, you can take some of the tension off of your triceps and more on your chest.

Next would be DB Pullovers. This is the prized exercise of the Pectoralis minor. Now, as we went over before, the minor group runs from the ribs up to the coracoid process on the scapula. It has no action on the arms, so keep this in mind. With the pull over, it is important to get a full stretch by taking your arms to at least parallel to the floor so we place the minor group under the greatest tension. On the upward phase we need to remember to draw our shoulders towards our knees to depress the shoulder girdle.

Lastly we have the incline barbell bench press. Although there is not inner or outer chest, there is technically a 'upper' chest. This refers to the sternal head of the Pectoralis major. This is differentiated by a grouping of fibers of the Pectoralis major that attach to the clavicle as opposed to the sternum. You can always pick out the people who do incline presses, and those who don't

Those are the most effective exercise for adding muscle mass to the chest. There is no inner or outer aspect of the Pectoralis major, so stop wasting your time trying to work it. It amazes me how many people insist on doing fly and cross-over exercises. I hope you can see why these types of exercises are don't have a place for adding mass to your chest. They are good for people who have weak or unstable shoulder joints and need to work on that area. However, if you don't have these types of problems, then don't. What about the stretch you ask? You think they really give you an added stretch and increased rang of motion?

Well as far as the range of motion, you are wrong. Your elbows will go to the exact same depth on a DB fly and a DB press. Yes, you will get a greater ROM than a barbell, but that is why we include DB press into the list of most effective exercises. And what about the stretch? Wrong again. If there is one thing you should take away from this article it is how to analyze movements regarding the chest. And the major point of analysis is what happens above the elbow. Remember, the Pectoralis muscle attach to the proximal (closest to the midline of the body) end of the humerus and the coracoid process of the scapula. There is no way that a different hand position will stretch the Pectoralis muscle.

What is that extra stretch you feel then? Well it is actually your biceps and the coricobrachiallis muscle. Going back to the first installment of the Harmony series, the biceps muscle run from the gleno-humeral (shoulder) joint to just below the elbow. And the coricobrachiallis runs from the coracoid process to the middle of the humerus. This is the stretch you feel. It is not the Pectoralis muscle. The only thing these exercises do is lighten the load placed on the Pectoralis muscle. Unless you can do flys with as much weight as you can do presses with, you shouldn't be doing them. Most of these exercises have been made up by personal trainers to keep their clients interested so they keep coming back and spending money. I don't know about you, but I'm interested in adding as much muscle in as little time and with as little effort as possible. I don't see any reason to waste time with those movements.

So I hope that I have shed a little light and cleared up some of the confusion. It is rather simple when you boil things down. There doesn't need to be 40 different exercises and you don't need some elaborate plan to hit the inner, outer and every corner of the same muscle group. Always be looking at things with a critical eye and ask yourself if what you are listening to even makes sense. Sometimes what you 'Feel' and what is really happening are not one in the same. Understanding the link between the structure and function of a particular muscle will help you to make the right decision, put together an intelligent program and start adding some high quality muscle mass.

Note: Click Here To Read 'The Lats'.