abduktion

Abduktion, from Latin abductio and abducere “to lead away,” is a term used in anatomy and other sciences to describe movement of a limb or body part away from the midline of the body. In the anatomical position, abduction is defined relative to that reference posture. It is the opposite of adduction, which moves a part toward the midline, and it increases the lateral distance between the body part and the midline.

In the limbs, abduction is a common motion at several joints. Shoulder abduction is primarily produced by the middle fibers of the deltoid along with the supraspinatus, and is typically accompanied by rotation of the scapula (scapulothoracic rhythm). Hip abduction involves the gluteus medius and minimus, and the tensor fasciae latae. Finger abduction refers to moving the digits away from the line that runs along the middle finger; the little finger and thumb have their own abductors as well. Abduction at the toes and other small joints follows similar principles, with muscle groups enabling lateral movement away from the body’s axis.

In other disciplines, abduction also denotes abductive reasoning, a form of inference aimed at identifying the best explanation for a set of observations. Developed in formal logic by Charles Sanders Peirce, abduction seeks plausible hypotheses and is widely used in diagnostic reasoning, hypothesis generation, and problem solving. It differs from deduction (deriving necessary conclusions) and induction (generalizing from examples).