Joints are the places in your body where two bones come together. They give us the freedom to move through the power of the muscles attached to these bones. Different parts of the body need different types of movements, so that is where joint types can vary. Joints can fall into three basic categories—freely movable, slightly movable and immovable. The types of joints that allow the most movement are called diarthrosis, or synovial, joints. Within this category of synovial joints there are various joint types, each with its own purpose.
Ball and Socket Joints
These are the largest of the synovial joints and are found in places in the body that need the fullest range of motion like shoulders and hips. They work just like the name describes—one bone with a ball on the end fits into the round socket of the other bone, allowing for full rotation.
Think of the function of door hinges. They allow movement back and forth, but not sideways. These are the types of joints found in the elbows, knees, fingers and toes. These joints can sustain injury when a force pushes them in a sideways manner. Knees are especially susceptible to this type of injury, especially during contact sports. Sometimes, braces with metal side supports are needed to treat or prevent this type of injury.
The function of these is, obviously, pivoting. Rotation is necessary in certain parts of the body, namely between the axis and atlas bones in the neck that allow your head to swivel. There are also pivot joints in the forearm that allow the ulna and radius bones to pivot.
These joints are where the oval shaped head of one bone fits into a similar shaped socket in the other. This shape of socket allows movement front to back and side to side, but not a full rotation. These joints are located in certain parts of the hand and wrist.
Saddle joints are found at the base of the thumb. The bones that come together at this joint consist of a concave and convex component, and fit perfectly together, almost like a rider on horseback. They allow both side to side and back and forth motion, with a small amount of rotation. It provides much-needed stability for the thumb that allows us to grip and hold things with our hands, and also for performing small movements such as writing, painting or sewing.
Protect These Important Joints
These types of synovial joints are all perfectly designed for the types of movements they need to do in each part of the body. Protecting these joints and making sure they are able to move freely and without pain is key to long-term health and mobility. If you experience discomfort in any joint or with any type of movement, see a doctor for a proper diagnosis.