So, here we have an example problem that wants us to rank the following joints in order from the least range of motion, which we'll label as number 1, to the greatest range of motion, which we'll label as number 4. And then it wants us to predict how this would affect their ability to provide structural stability and support. Notice that the four joints we're showing you here in this example are the shoulder joint, which is found in our shoulder connecting the humerus to the scapula. The sutures of the skull are also a joint, and those sutures are essentially the cracks that you can see in the skull highlighted there. We also have the intervertebral joints, which are found in our spine in our back.
Lastly, we have the knee joint, which is found in our knee. In terms of the range of motion, we can go through each of these one by one. Our shoulder joint allows for quite a lot of movement. Our spine allows us to lean forward and lean backward, which also permits some movement. Our knee joint allows for movement of our knee.
However, what you'll notice is that the sutures of the skull, the cracks essentially that you can see here highlighted in the skull, are not very mobile. They do not have a great range of motion; they have very low range of motion. For that reason, they have the least range of motion of all the joints here, and we can label the sutures of the skull as number 1. Our spine does allow for some motion; we're able to lean forward and lean back. However, the range of motion of our spine is limited and does not allow for as great of a range of motion as the knee or the shoulder. Thus, the intervertebral joint is going to be number 2 in terms of the order or the ranking of the range of motion. The knee has less range of motion than the shoulder, so we can label the knee joint as number 3, and the shoulder joint has the greatest range of motion of all these joints, and we'll label it as number 4.
Now that we've ranked these four joints in terms of their range of motion, let's focus on their ability to provide structural stability and support. Recall from our last lesson video that there is an inverse relationship between the skeletal mobility of a joint and the structural stability of a joint. The greater one is, the less the other is. The greater the range of motion a joint has, the less stable that joint is. The shoulder joint here has the greatest range of motion of these four joints.
Because it has the greatest range of motion, it also is the least stable. That makes it more prone to injuries such as dislocations, for example. The sutures of the skull, the cracks that you can see here in the skull, are going to have the least range of motion among these four joints. Because it has the least range of motion, it has the greatest structural stability among these four joints. That's going to be very important for the skull to have great structural stability because the skull plays a critical role in protecting our brain.
Of course, we want to prioritize structural stability and support when it comes to the skull and protecting our brain. This here concludes our example problem, and we'll be able to get some practice applying these concepts and learn a lot more about joints as we move forward. So, I'll see you all in our next video.