What does transverse (horizontal flexion) refer to?

Transverse (horizontal flexion) refers specifically to the movement that occurs in the transverse plane, which involves moving a limb towards the midline of the body from a position where it is raised or abducted. When considering the movement from a 90° abducted arm position towards the midline, this action illustrates transverse flexion as the arm pivots horizontally back towards the centerline of the body.

This type of movement occurs primarily at the shoulder joint and demonstrates how limbs can be maneuvered in a horizontal direction. In this instance, the arm is already positioned to the side, allowing for a clear representation of transverse flexion as it moves inward. Thus, option B accurately encapsulates the definition and mechanics of transverse (horizontal flexion) as it relates to limb movement.