What term describes the action of rotation around the long axis of a structure?

The action of rotation around the long axis of a structure is defined as rotation. This term specifically refers to the movement where a bone or limb turns on its longitudinal axis, which can involve either internal (medial) or external (lateral) rotation depending on the direction of the turn. For example, when you rotate your arm inward, this is an example of internal rotation, whereas turning it outward represents external rotation.

In anatomical terms, rotation is a fundamental movement that occurs in various joints, such as the shoulder and hip, allowing for a diverse range of motion. Understanding this action is crucial for comprehending how different movements work in sports, rehabilitation, and functional anatomy in general.

The other terms listed refer to different types of movements. Abduction involves moving a limb away from the midline of the body, circumduction is a circular movement that combines flexion, extension, abduction, and adduction, and elevation refers to lifting a body part superiorly. None of these effectively describe the specific action of rotation around an axis, which makes rotation the correct term to use in this context.