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