Movement: Take the arm to be stretched and place it across the neck. Use the opposite hand for support at the elbow. Push the elbow to the neck with the off arm and hold for the desired time. Repeat with the opposite arm.
Repetitions: Hold for the full prescribed time on one side, then switch sides and repeat. This counts as one set.
Instructions and effects for the Rear Deltoid Stretch - Across the Neck exercise 
Movement in Frontal Plane