Gliding
Gliding is the simplest type of motion. It is one surface moving over another without any rotary or angular motion. This motion exists between two adjacent surfaces.

Angular
Angular motion decreases or increases the angle between two adjoining bones. The more common types of angular motion are as follows:

Flexion-bending the arm or leg.
Extension-straightening or unbending, as in straightening the forearm, leg, or fingers.

Abduction-moving an extremity away from the body.
Adduction-bringing an extremity toward the body.

Rotation
Rotation is a movement in which the bone moves around a central point without being displaced, such as turning the head from side to side.

Figure 1-26.-Example of immovable, slightly movable, and freely movable joints.

Circumduction
Circumduction is the movement of the hips and shoulders.

Other Types of Movement
Other types of movement generally used to indicate specific anatomical positions include the following:

Supination-turning upward, as in placing the palm of the hand up.

Pronation-turning downward, as in placing the palm of the hand down.

Eversion-turning outward, as in turning the sole of the foot to the outside.
Inversion-turning inward, as in turning the sole of the foot inward.