Functional Anatomy vs Origin-Insertion Anatomy

Jun 22, 2022

Function- (Gary Gray NASM). All lower body muscles function to prevent flexion or create extension. 

Anatomy is a funny science. In college we were taught what I can best describe as origin-insertion cadaver anatomy. I like to refer to it as dead person anatomy.

The instructor would show us a muscle and say  “this muscle originates here and inserts here”. We were taught the boney prominences of these origins and insertions and told to memorize them. We were then taught the supposed function of the muscle.

In the case of a muscle like the quadriceps we were told that if the quadriceps were to shorten the lower leg would extend.  If we look at simple mechanics, this seemed really logical. Unfortunately, this was also the part that ended up not being very true and, this is where we begin to distinguish between the idea of origin-insertion anatomy and functional anatomy. 

The semi-truth is that If you had a cadaver and, if you could somehow produce a muscle contraction in a dead body, and you let the lower legs hang off the table, a quad contraction would cause the leg to extend. However, this does not make the quad a knee extensor in real life.

In the same way, if you flipped a cadaver over and were able to cause the hamstring group to contract, the heel would move toward the butt. However, that does not mean that the hamstring flexes the knee. The cadaver anatomy we were taught in school just doesn't seem to hold up in real life.

How many times have we heard that everything changes when the foot hits the ground. I think this statement, Everything Changes When the Foot Hits the Ground, was one of the early titles of a Gary Gray seminar and could not be more true.

Lets use the same quadricep muscle as the example. If you are walking and you put your foot on the ground, at the moment the foot strikes the ground does the quad extend the knee? If it did, I think you would go backward instead of forward.

In fact what happens when the foot hits the ground is that all of the muscles of the lower body act eccentrically and in concert to prevent the joints of the lower body from flexing. So, the real function of the quadriceps  ( and the glute, hamstring, gastroc etc) is to prevent flexion of the ankle knee and hip.

I first learned this concept in the early 90's at a Gary Gray-Chain Reaction seminar in Phoenix and was thrilled. Gray's concepts allowed me to throw away all the isolation machines that cluttered my weight room. The concepts also gave me the courage to remove all the isolation exercises that were supposed to strengthen specific muscles and prevent injuries. For me, it was the first big step in the development of what we now call functional training.

Gray's analysis was simple.

The anatomy that we had been taught in school simply made no sense. When held up to the lens of real life, the old origin-insertion anatomy was a flawed way of teaching that left us unprepared for the real world. 

Mike Clark of NASM fame made it more clear in the first NASM courses. It took me a while to catch on but, over time I realized that the answer to every question on the NASM test was basically the same. If the NASM test asked you what a muscle did at ground contact you answered “eccentrically decelerates flexion of the ankle, knee and hip”. When the NASM test asked you what happened at toe off the answer switched to “concentrically extends the ankle, knee, and hip”. 

The answers were now so simple.

It was understanding the concept that was hard. The fact of the matter is that in real life none of the muscles behaved in the manner we were taught. Instead they simply acted together as stabilizers or movers to prevent flexion or create extension.

The big key with functional anatomy is that we begin to look at the muscles and joints as a system that works together, not as a bunch of isolated joints. It's not about what happens at one joint but the synergy of groups of joints acting together to create motions like running or jumping. If we see knee extension or knee flexion as separate, we miss the point.

I like to say that the only guy who uses his quad to extend his knee is the one legged man in the ass kicking contest!