Musculoskeletal refers to our muscles and bones and is the body's framework. When we move, the muscles, joints, and bones are designed to move in a symphony, each doing their job.
In the most simplistic form, body movement starts with a nerve impulse to a muscle. This impulse causes a muscle to twitch, or contract, which pulls a tendon (or ligament). Tendons are attached to bones. Together they create skeletal movement.
Poor posture creates an improper balance between the bones and the muscles. Movement requires some muscles to contract while other muscles work to stop them from moving too much. Without good musculoskeletal balance, some joints become distorted causing undo stress on that joint. This is where a lot of shoulder problems coming in, because people don't know about their shoulder blade muscle knot.
A good example is swinging a tennis racket: Muscles in the chest, shoulders and back begin the motion, while other muscles in the back and rotator cuff stop the swing. Without correct muscle balance there is no "brake" from the shoulder becoming dislocated.
The same scenario occurs with all movement, from taking a walk to rolling over in bed. Poor posture creates imbalance. These imbalances translate into other areas of your body, to the point where you have to ask yourself how to get buffalo hump treatment, because it's gotten that bad.