What movement is defined as adduction of the scapula?

The movement defined as adduction of the scapula is retraction. Retraction occurs when the scapulae move closer together along the back, which is often visualized by squeezing the shoulder blades together. This action is primarily facilitated by muscles such as the rhomboids and the middle fibers of the trapezius.

Adduction, in the context of scapular movement, specifically refers to the motion of bringing the scapulae toward the midline of the body, which is precisely what retraction accomplishes. This is important for proper posture and shoulder stabilization.

The other movements listed do not involve this specific action of bringing the scapulae together. Protraction refers to the movement of the scapulae away from each other, which is the opposite of adduction. Internal rotation involves the rotation of a limb's joint towards the center of the body, and circumduction is a circular movement that combines flexion, extension, abduction, and adduction, typically seen in limbs rather than the scapula.