Joints are classified according to their permitted range of motion (category – type – description – examples)
- Synarthrosis (provides no movement) – suture – fibrous connective tissue between bone surfaces – between cranial bones and facial bones
- Amphiarthrosis (slightly movable) – symphysis – disc of fibrous cartilage between bones – between vertebrae and pubic bones
- Diarthrosis (freely movable synovial joints):
- ball and socket – movement in all planes – scapula and humerus also pelvic bone and femur
- hinge – movement in one plane – humerus and ulna also femur and tibia and between phalanges
- condyloid – movement in one plane, with some lateral movement – temporal bone and mandible
- pivot – rotation – atlas and axis also radius and ulna
- gliding – side-to-side movement – between carpals
- saddle – movement in several planes – carpometacarpal of thumb
Synovial Joints are classified as:
- gliding
- hinge
- pivot
- ellipsoidal
- saddle
- ball-and-socket
Each kind permits a different type and range of motion.
- Gliding joints have flattened or curved faces that allow for slight movement across connecting surfaces. Although movement is possible, ligaments usually restrict such movement. Gliding joints are found at the ends of the clavicles, between the carpal and tarsal bones, and between the articular facets of adjacent vertebrae.
- Hinge joints permit angular movement in a single plane, as with the opening and closing of a door. Hinge joints are found between the occipital bone and atlas in the axial skeleton, and the elbow, knee, ankle, and interphalangeal joints of the appendicular skeleton.
- Pivot joints allow only for rotation as found between the atlas and axis enabling the rotation of the head. They are also found between the head of the radius and the proximal shaft of the ulna, permitting pronation and supination of the palm.
- Ellipsoidal joints allow angular motion in two planes – along or across the length of an oval. In an ellipsoidal joint, an oval articular face is nestled within a depression of an opposing surface. Such joints connect fingers (metacarpal bones) and toes (metatarsal bones).
- Saddle joints have articular faces resembling saddles. Each face is concave on one axis and convex on the opposing surface, thus permitting angular motion, but preventing rotation. Saddle joints are found at the base of the thumb (carpometacarpal joint). Twiddling the thumbs is the best example of movement of the saddle joints.
- Ball-and-socket joints occur at the shoulder and hip. The round head of one bone rests within a cup-shaped depression of the other allowing for a combination of movements.
