The term motion implies the capability that you have to move your joint in various directions. There are a number of things that determine it. The most fundamental among these is how the inner parts of your joints are working. Also important in this case are the structures that surround it. When you stretch on a regular basis you can be sure that you will be able to perform a wider range of motion. If you wish to know how stretching can help with these structures the first thing that you need to do is be familiar with them. You also need to know in this context as to how they can help the movement of a joint or hinder it.
Joints are basically the connecting points of our body – in that sense they can be called junctions. Normally, there are three kinds of joints as far as architecture is concerned – hinge, ball in socket, and pivot. It is basically the architecture of your joint that determines how your bones would be able to move.
Muscles normally surround the joints and it is from the muscles that you get the energy needed to move these joints. The extent of motion that a joint can achieve depends to a significant extent on the amount of tension that the particular muscle has. There are many passive factors that can have an effect on muscle tension. Examples of such factors would be your regular posture or a scarred tissue. There are some active factors that are important in these cases as well. Examples of such factors would be muscle contractions that are done intentionally and muscle spasms that are more involuntary in nature.
Tendons are basically cords that are flexible and built of strong tissues. They help you move and connect bones and muscles. Whenever a joint is moving energy emanating from the muscles gets transferred to the tendons which are hanging on to the bones.
Ligaments are basically bands of tissues. They happen to be fibrous and tough by nature. They either bind one bone to another or a bone and a cartilage. They normally occur at joints. One of the most prominent examples, in this case, would be an anterior cruciate ligament or ACL. It is one of the 5 ligaments that are supposed to combine and help the knee move. One of the various functions that an ACL does is to make sure that your knee joint does not rotate in an excessive manner.
When you are stretching you are basically working your tendons and muscles rather than your ligaments. Your ligaments are not supposed to stretch like elastic. Do not assume that if your ligament is excessively stretchy you would get the support and stability that you need in order to perform a wide range of movements in a safe manner.
However, you need to keep in mind that if you are a senior citizen it is better to do these stretching exercises under the supervision of an expert unless you happen to be one yourself.