Now we have talked about all the shoulder bones. The point that I wanted to make overall was that raising your arms above your head in a useful manner is more technical than you might have imagined. Sure, you can lift them up right now, no problem. You can grab things off the top shelf. Small potatoes, people. If you want to use your arms for any activities that require real strength or stability, you need to know what you're doing (if you are totally happy with your computer life and bad posture and have no foreseeable future doing anything else, you can skip this post). Work with me here - the image here is of your right shoulder girdle. Imagine you wanted to lift your right arm. The humerus there will rotate out towards us, applying pressure backwards. Your clavicle does not have a mind of its own, so ignore that for now. The scapula, however, can sit wherever it likes. Look at that acromioclavicular point - the acromion - and now you might see that it could get in the way of the humerus' freedom to full extend. If the humerus cannot fully extend, it can neither maintain its stability, nor bear large amounts of weight. Think about trying to stand on one of your legs if you couldn't strengthen it and had to tilt all your weight off to the side. Reverse scenario: the scapula slides closer to the spine and down towards the pelvis. OUT OF THE WAY. Now the humerus is free to straighten out, and it can use the scapula for support, at the same time! Essentially you've gotten your leg in a straight line, your pelvis lined right on top of it, and you could hang here for hours.

Good posture will do you wonders. Straight spine. Shoulders back and down. Inhale and fill up your chest with air. Conquer the world.