Whenever anyone is under duress, they hold their breath. For instance if someone frightens them, they suck in their breath and hold on to it until they relax again. Gradually, because of our exposure to so much adversity, this habit of sucking in breath and holding on to it becomes a way of life. The exodus from being centered is set in motion. When you are emotionally tense your muscles and then the rest of your body becomes tense, eventually this is the pattern stored in your cells' memory.
Tension causes muscles to become shorter, compacted and very hard, losing their fluidity.
Gradually your muscles accept the message that they need to shift shape, that they are far too long, so your muscles become contracted. The now shortened muscles in your neck are literally jamming your skull onto your shoulders, creating stress throughout your body. Your skull, which is made up of 32 component bones, expands and contracts as you breathe in and out. The natural processes of your entire body are inhibited. This creates pressure on your brain, and a dull dysfunctioning mind.