Joints

A joint is a part of the body that links two or more bones together. Joints enable bones to pivot, rotate and glide relative to one another, which is essential for movement in different parts of the body.

synovial joint is the most common type of joint in the body. It allows for a wide range of movement between bones. Synovial joints are found in various locations, such as the hip, shoulder, elbow, and knee. They are crucial for both enabling movement and maintaining flexibility and mobility.

Some examples of synovial joints are:

  • Pivot joints – Only allow rotary movement around a single axis (e.g. joints in the neck)
  • Hinge joints – Only allow movement in two directions (e.g. elbow and knee joints)
  • Ball and socket joints – Allow movement in all directions, within certain limits (e.g. shoulder and hip joints)

The diagram below shows a synovial joint.

Anatomical diagram of a joint, highlighting its components including the articular cartilage, joint cavity filled with synovial fluid, synovial membrane, joint head, joint capsule, bone, muscle, socket and tendon.

Fixed joints are a type of joint that does not allow for movement between the bones. For example, the joints between the bones in the skull. Fixed joints play an important role in providing stability and support to the body. This is because they allow the bones to remain in place, protecting vital organs and maintaining the body’s structure.

The Anatomy of Movement

Bones cannot move on their own; they require muscles for movement. Muscles are a type of tissue that is responsible for movement in the body. They are connected to bones by tendons, which are tough, fibrous cords. Tendons transmit the force generated by muscle contractions, allowing bones to move.

At the point where two bones meet, there is a layer of cartilage, which is a type of connective tissue that covers the ends of the bones. Cartilage acts as a cushion to prevent bones from rubbing against one another. It also helps to absorb shock and reduce wear and tear on the joints.

Synovial fluid also helps to reduce friction and allows the joints to move freely. This fluid is produced by the synovial membrane, and it acts as a lubricant to enable smooth movement between the bones.

Ligaments are strong, flexible bands of connective tissue that stabilise joints by connecting bones and helping to prevent dislocation.