Had dinner with a neighbor, a criminal defense lawyer, who recently started carrying. He just completed a training course so we talked about it. He was a bit confused about the term "center mass" since he was led to believe that it means anywhere on the torso. I took polite exception to his instructor's position, and I offered a narrower description of the term.
I said center mass was the thoracic area of the torso, the place where the vital organs and the major circulatory vessels are located. Pulling up some images from the web, I showed him what I meant. Then I thought this topic might be of interest to others who are interested.
In the Corps I learned center mass to be an area from the clavicle bones down to the bottom of the central rib cage (10th rib). That is the space in which the lungs, heart, and major veins and arteries are housed. I have posted a photo showing what is where in that space. You will see that it a life sustaining center.
The thoracic cavity is divided by the sternum (breast bone), which is about 6 inches long, tapers from about 2 inches at the top to less than 1 inch at the bottom, and is only about 1/4 inch thick. A very hard punch to the sternum can fracture it, and that can be an incapacitating injury. It can even stop the heart if the force is heavy enough.
The ribs attach to the sternum by cartilage, softer than bone. The ribs are not very thick. The sternum, cartilage, and ribs can easily be penetrated by even the 22 LR. On either side of the sternum are the lungs. A punctured lung will usually incapacitate a person in short order. To the left of the sternum and just above the bottom of the rib cage lies the heart. A shot there is incapacitating if not lethal. Proceeding down from the clavicle bones are the subclavian arteries and veins, and proceeding up are the jugular veins and carotid arteries. A hit on any of those vessels will end up in bleeding out and quick loss of consciousness due to extreme blood pressure drop.
With the above in mind I explain why you should aim for the sternum and consider it as the center of center mass. Referencing the picture will help you see the subtleties. If you aim at the sternum and miss it, you still are target rich. Hit either side of it and you hit a lung. Hit low and to the target's left you might hit the heart. Hit high left or right and you might hit a major blood vessel. But what happens if you hit very high?
Assuming that you stay centered a high miss of the sternum will hit either the throat or the mouth. Both are very unprotected areas. A bullet can pass through them relatively easily compared to dense muscle tissue or bone. The benefit of such a hit is that there's a good chance the bullet is going to pass into the spinal column or very close to it. That can vary from lethal to crippling.
I learned these things in 1967 after my second tour in Nam in the infantry. I went to recon training. We had to learn how to gunfight with the M1911. What you just read was part of that training. I just thought it might be good to offer it for anyone who might be interested.
[IMG]
[/IMG]