IB SEHS - Joints
A joint or articulation is
where two or more bones come into contact or articulate with each other
Pivot joint
One bone forms a ring in which the other bone rolls or pivots allowing rotation of the joint, for example the radius rotates around the ulna at the radioulnar joint.
Three main types of joints
fibrous, cartilaginous and synovial
Meniscus
A small disc of fibrocartilage that helps bones fit together; found in the knee joint
Ball and socket joints
Can move in all directions and therefore have the greatest amount of movement. They are formed when the sphere shaped head of one bone fits into a rounded cavity on the other bone, for example the shoulder and hip joints
Ligaments
Connect bone to bone and provide stability
Tendons
Connect muscle to bone
Articular cartilage
Covers the surface of bones; reduces friction; absorbs shock
Bursae
Fluid-filled sacs found in areas of high stress
Condyloid joints
Formed where an oval or egg-shaped convex surface fits into a reciprocally shaped concave surface. For example, they are found between the radius and carpal bones of the wrist and allow movement in two directions
Fibrous joints
Have a thin layer of fibrous tissue connecting the edges of the two bones; found in the skull; no mobility
Synovial fluid
Lubricates joints and provides oxygen and nutrients to cartilage
Jont capsule
Seals the joint space and prevents dislocation
Saddle joint
The bones are shaped like a saddle and a rider sitting in the saddle. An example of a saddle joint is found between the metacarpal of the thumb and the carpal bone next to it.
Cartilaginous joints
The bones can be separated by a fibrocartilage disc; found between the vertebrae; limited mobility
Synovial joints
The most commonly occurring joints in the body; have the greatest mobility
Joint cavity
The space between two bones
Gliding joints
These joints are found between the tarsal bones and between the carpal bones; have the least amount of movement
Hinge joints
These joints are found in the elbow and knee. The surface of one bone is convex and fits into a reciprocally shaped concave surface
Types of synovial joints
gliding, hinge, pivot, condyloid, saddle, and ball and socket joints
The more movement a joint has...
the less stable it is and the greater its risk is for injury (generally speaking)
The main function of joints is
to increase mobility of the body and limbs