The skeletal system is made up of bones. When two or more bones or pieces of cartilage meet, it's called a joint. Typically, joints have connective tissue or cartilage in them, as well as synovial fluid in synovial joints. Joints allow movement and flexibility in the skeletal system. There are three different kinds of joints.
Fibrous
Fibrous joints are joined together by fibrous connective tissue. They can also be termed synarthroses. Examples of these joints, as listed in Netter's Clinical Anatomy, include the sutures of the skull, which are the flat bones of the skull; syndesmoses, which are two bones that are connected to each other by a fibrous membrane, such as the ulna and radius in your arm; and gomphoses, which describes your teeth fitting into a tissue-lined cavity.
Cartilaginous
Cartilaginous joints consist of two bones joined by cartilage, or fibrous tissue and cartilage, according to Netter's Clinical Anatomy. They are also called amphiarthroses There are two types of this kind of joint: primary joints and secondary joints, which refer to the types of surfaces they join. The function of primary joints is slight bending and growth, and secondary joints help with strength and flexibility. One example of this joint is your spine, which has secondary cartilaginous joints.
Synovial
There are many different kinds of synovial joints, also called diarthroses. These joints are typically associated with a wide range of movement and are grouped with regard to their shape and the movement they enable. Different kinds of movement include extension and flexion, rotation and gliding motions. Types of synovial joints include hinge, pivot, and ball-and-socket joints. Examples include the top of your femur and your hip, your fingers and your elbow.
References
- Netter's Clinical Anatomy (2nd Ed), John T. Hansen, 2010
- medical-look.com: Skeletal Joints
