Without joints, your body would not be able to move. They provide a place for muscles, bones, ligaments and tendons to connect. After the brain sends a signal to move, the appropriate muscles contract and pull on the bones. In addition, your tendons and ligaments stabilise the movement.
Your body has more than one kind of joint. Your body has joints that do not move called synarthroses. It also has joints that only allow small amounts of movement called amphiarthroses. The last classification is diarthrosis joints, which allow more movement. There are six types of diarthrosis joints. Each type of joint determines what motions a specific area of your body can do.
A hinge joint is exactly as it sounds and works like a hinge on a door. It permits only flexion and extension. For example, the elbow joint is a hinge joint that allows you to straighten and bend your arm. When you straighten a joint the movement is called extension. When you bend the joint the movement is called flexion.
A saddle joint is designed to allow a wide range of motion. It is where two bones come together in a way that allows them to support one another. The only saddle joint in the body is in your thumb. It allows your thumb to bend, straighten, rotate and reach across the palm.
Ball and Socket Joint
In a ball and socket joint, the end of one bone is rounded and the other bone is curved inward. These types of joints allow the most movement. Examples are your hip and shoulder joints. They also are the most susceptible to injury due to the amount of movement they allow.
A pivot joint allows you to turn or rotate. It contains one bone that is rounded while the other bone has a ring shape on its end. Your neck contains a pivot joint, so you can turn your head to look side to side and tip it to the side.
A gliding joint consists of two bones that both have a flat surface. This allows them to glide over one another to allow movement. This type of joint also allows circular movements. These joints are found between the bones of the fingers and toes. They allow your fingers and toes to move up and down and side to side. There are also gliding joints in your wrists and ankles.
Condyloid joints allow flexion and extension and a small amount of rotation. An example is your temporomandibular joint or jaw joint. The knuckles in your fingers and toes are also condyloid joints.
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