What are Joints?

Definition: A joint is where two bones come together. The joints hold the bones together and allow for movement of the skeleton.

The Human Skeleton

(Front view)

(Side view)

(Rear view)

All of the bones, except the hyoid bone in the neck, form a joint. Joints are often categorized by the amount of motion they allow. Some of the joints are fixed, like those in the skull, allow for no movement. Other joints, like those between the vertebrae of the spine, allow for some movement. Most of the joints are free moving synovial joints. Arthritis can affect any type of joint, but these joints are the most affected.

Some of the common joints affected by arthritis and joint pain are:

Ball and Socket Joint: This type of joint allows for a wide range of rotation and movement. The shoulder and hip are ball and socket joints.

Condyloid Joint: This type of joint allows movement but no rotation. There are condyloid joints in the jaw and fingers.

Gliding Joint: This type of joint allows bones to glide past each other. There are gliding joints in your ankles, wrists and spine.

Hinge Joint: This type of joint allows for movement much like that of a door hinge. The knee and ulna part of the elbow are hinge joints.

Pivot Joint: This type of joint allows bones to spin and twist around other bones. There are pivot joints in the neck and the radius part of the elbow.

Saddle Joint: This type of joint allows for back and forth and side to side motion but limited rotation. There is a saddle joint in the thumb.

Also Known As: articulation

Common Misspellings: joynts, jionts

Examples: The hip is a ball-and-socket joint.

_{Sources: Synovial joint, Wikipedia; The Joints, The Shock Family Web Page; Joint Index, Wheeless' Textbook of Orthopaedics}