# Describing Motion

The first description of motion is its type.

Rotatory Motion is movement of an object or segment around a fixed axis in a curved path.

Translatory Motion is the movement of an object or segment in a straight line.

The next description of motion is location.

The transverse (horizontal) plane divides the body into upper and lower halves. Movements in the transverse plane occur around the longitudinal axis.

The frontal (coronal) plane divides the body into front and back halves. Movements in the frontal plane occur around the anterioposterior axis.

The saggittal plane divides the body into right and left halves. Movements in the saggital plane occur around the coronal axis.

Motion in any of these planes means that a body segment is being rotated about its axis or translated in such a way that the segment is moving through a path that is parallel to one of the three cardinal planes.

The next description of motion is direction.

Flexion is a bending movement that decreases the angle between body segments.

Extension is a straightening movement that increases the angle between body segments.

Abduction is a movement that pulls a body segment away from the midline of the body.

Adduction is a movement that pulls a body segment closer to the midline of the body.

Lateral Flexion is a sideways bend of a body segment.

Internal rotation refers to rotation body segments toward the center of the body.

External rotation refers to rotation of body segments away from the center of the body.

The last description of motion is quality.

The quality of a rotary motion is synonymous with range of motion and is measured in degrees.

Translatory motions are measured by the linear distance through which the object has moved.