More people than ever sit in front of a computer for a living these days, and if you're reading this online it's likely that you're one of them. So before you get back to being productive for your boss, let's review some ways you can spare your neck in the process.
First, the basics: Your head weighs, on average, about 12 pounds. You have a fairly complicated series of joints and muscles holding that weight off your shoulders and giving you the freedom to look around. Like every other complicated system, the more moving parts to deal with, the more likelihood for something to go wrong. Some of the muscles that get tweaked and stretched when your head moves too far forward (the classic computer posture) are the deep flexor muscles. That would be these guys:
These muscles work in concert with others in the posterior aspect of your neck to give both stability and freedom of movement to the head. They also get beat up when we get our heads too far forward and keep them there all day, like you may very well be doing right now. Interesting fact--every inch forward your head moves takes three times more power to support the weight. Makes sense--if you hold a bowling ball close to your body it's easier to support than holding it out in front. And your head weighs about the same as a bowling ball. No disrespect.
Eventually, certain muscles get too tight which causes others to turn off ("reciprocal inhibition," again). This happens because muscles activated on one side of a joint cause the muscles on the other side of the same joint to become inhibited--when you flex your bicep, your tricep has to turn off so you can perform the movement. Your neck is no different, and when it happens for hours on end in only one direction neck pain is often the result. This is sometimes referred to as "upper crossed syndrome." It looks like this: