What is the term for lateral-rotational movement away from the midline in the transverse plane?

• A. Horizontal abduction
• B. External rotation
• C. Internal rotation
• D. Horizontal adduction

Answer: (A)

In the transverse plane, movements along the horizontal axis include abduction/adduction and rotation. The term for moving a limb away from the body's midline in that horizontal direction is horizontal abduction. Abduction means moving away from midline, and when this occurs within the horizontal plane (moving side-to-side rather than up or down), we describe it as horizontal abduction. So, moving the arm laterally outward from the body in the transverse plane is best described as horizontal abduction. Horizontal adduction would be moving toward the midline in that same plane, and internal/external rotation refer to turning the limb around its long axis rather than simply moving away from midline in the horizontal plane.