So here we have an example problem that asks, which of the following is not a unique characteristic of synovial joints? And we've got these 4 potential answer options down below. Now option A says dynamic movement. Recall from our last lesson video that synovial joints are always functionally classified as diarthroses because they allow for dynamic or free movement. And so really, this is a unique feature of synovial joints because the other structural classes of joints, including the fibrous joints and cartilaginous joints, do not allow for this dynamic movement. And so really synovial joints are the only ones classified as diarthroses, and they're the only ones that are going to allow for this dynamic movement. So dynamic movement is a unique feature of synovial joints, and for that reason, we can cross this option off of our list because we're looking for the feature that is not unique to synovial joints.
Now moving on, option B says ligaments. And so again, ligaments can be found reinforcing synovial joints. However, ligaments are not unique to synovial joints because ligaments can also be found in the other structural classes of joints, including some fibrous joints and some cartilaginous joints. And so for that reason, ligaments is a characteristic that is not unique to synovial joints. And for that reason, option B must be the option that we are looking for. So we can go ahead and indicate option B as the correct answer to this problem. But just in case, let's check the last two options here.
Option C says articular capsule, and recall that this consists of 2 layers, the inner synovial membrane and the outer fibrous layer. And so the articular capsule is a unique feature or a unique characteristic of synovial joints. So for that reason, we can cross it off this list. And then option D says synovial fluid, which acts as a lubricant and a shock absorber in the synovial cavity. And so it is again a unique feature of synovial joints, so we can cross it off this list. And so option B, ligaments, is the only option here that is not unique to synovial joints, so that is the correct answer. That concludes this example, and I'll see you all in our next video.