I've tried to break down the complex phenomenon of joint laxity in this post on hypermobility. Sometimes a visual can make a concept easier to grasp. This movie contains an example of my shoulder (glenohumeral) joint moving relative to itself -- something you don't want to happen if you value long-term function of your joints.
Watch how a load (a 21-pound baby) in my arms can cause my arm bone to move away from my scapula -- applying a tensile load to the ligament instead of the shoulder muscles.
While hypermobility is complex, the corrective -- stabilizing the joint -- is fairly simple. Which isn't to say that it's easy. I catch myself screwing my ligaments over 1,000 times a day. All I can do is work on my awareness and my muscles and connective tissue 1,001 times a day and slowly accumulate the benefit of tiny changes.
They say that a picture is worth a thousand words. Which means that a video must be worth a million words. And since thoughts are worth a penny, and thoughts are typically about a hundred and fifty words, this post is clearly worth $66.00. I'll take your payment in kind thoughts or you can donate $66.00 to good times. Either works for me.