Your range of motion is how far you can move a joint in different directions is determined by a few things: starting with the inner workings of the joints. Another determining factor of joint motion is how much tension are in the muscles surrounding the joint, which can be affected by by passive factors such as scarring your posture, or by active factors such as involuntary muscle spasms or purposeful muscle contractions.

Stretching exercises can help you  improve your range of motion. To understand how, it helps to know what joints, tendons, and ligaments do:

• Joints are the junctions that link bones together. The architecture of each joint – that is, whether its structure is a hinge, pivot, or ball-in-socket – determines how the bones move in relation to one another.
• Tendons are flexible cords of strong tissue that connects the muscles to bones.
• Ligaments are tough, fibrous bands of tissue that connect bone to bone, or bone to cartilage, at a specific joint. An example is the anterior cruciate ligament (ACL), one of five ligaments that together control the movements of the knee. The ACL prevents the knee joint from rotating too far.

Stretching works the muscles and tendons, but not the ligaments. The ligaments are not supposed to be elastic. If a ligament was abnormally stretchy, it would not provide the stability and support you need for a safe and normal range of movement.