If you are working at a computer for long periods of time and your head is held forward additional stress is placed on the jaw joint.  The ability to open the mouth is strained and more muscle contraction is needed to perform the action.   Try it out:  Sit tall and then open your mouth.  Did it open easily and smoothly?   Now sit as though you are working at a computer and push your head forward so that your ears are in front of your shoulders.  Now try the exercise again.  Did you notice a difference?  Was it harder to open?  Was there any clicking?  Could you open it as far?  Did you experience any pain?

If you have this type of posture the muscles of the jaw and face become strained, fatigued, and sore and/or develop trigger points. (Refer to earlier posts for a description of trigger points)

These trigger points can create symptoms such as tooth ache, itch in the ear, ear aches, eye twitching, symptoms similar to sinus problems in addition to causing headaches.   So it important to constantly monitor your own posture and be aware of where your head is in comparison to your body.  Correct posture is having your ears in line with your shoulders.  Ear aligned with shoulder

In order to accomplish this, an exercise can be performed daily to strengthen the weak muscles of your neck and stretch the shortened muscles.   

When tucking your chin back make sure that you’re looking out of the top of your eyes.  You will hurt your neck if you try this exercise while looking out of the bottom of your eyes.    Start with 10 repetitions holding the head back for 5 seconds each time. Repeat this twice per day.  If you experience more pain, reduce to once a day only.  For a demo you can visit: http://www.youtube.com/watch?v=fE9jjfLtO9A.