Our musculoskeletal system consists largely of bones and muscles. The joints, which connect different parts of the skeleton, allow us to move. Depending on where the joints are in the body, and how much, and in which direction, they need to be moved, they may develop in different ways. There are different types of joints. A few examples include hinge joints, ball-and-socket joints and swivel joints. For example, a ball-and-socket joint consists of a joint head (condyle) and joint socket. The socket is roughly formed like a hollow (fossa), and the joint head fits into it. Both ends are covered with cartilage, so that they can move against each other without getting stuck. If the cartilage breaks down, you can develop problems with stiffness and pain, so-called osteoarthritis.
Hinge Joint Examples
A hinge joint is a type of joint that can only be bent in the plane of motion. Finger joints, the elbow and knees are examples of this type of joint. However, the elbow is a complex joint that involves two different joints, a hinge joint and a swivel joint. These are enclosed by a overall joint capsule. The combination of different joints means that we can bend stretch and twist our lower arm smoothly. The knee joint is also a complicated joint – actually the most complicated in the entire body. Here we have parts that cannot normally be found in our other joints such as knee ligaments, the meniscus and a kneecap. This is because our knees need to be able to tolerate significant strain.
Ball-and-Socket Joint Examples
In contrast to a hinge joint, a ball and socket joint can move in all directions. The hip joints and shoulder joints belong to this category. Both of these joint types have the disadvantage that, due to their enormous range of motion, they can become relatively unstable and come out of the joint. A ball-and-socket joint gets its name since the head of the joint looks like a ball. This is also why it gives us such a large range of motion. The shoulder joint is actually the joint in the body that has the most mobility. The hip joints are not as flexible since they must bear more weight and therefore need to be more stable.
Examples of Swivel Joints
For this type of joint, the ends of the bones can only be twisted in relation to each other. No other joints are involved in this motion. We do not have very many swivel joints in the body, but the most common example is the joint that is built into the elbow joint. This type of joint, however, can also be found in the neck and allows us to be able to turn our head.
Double Axle Joints/Saddle Joints
Double axle joints are also called saddle joints because both joint surfaces are shaped like a saddle. They can be moved forwards, backwards and sideways. The best example of this type of joint is the thumb joint, but also the rest and ankles.
Read about the anatomy of the knee.