Cerebral motor or brainstem Integrity may also be assessed.Ask the client to close his or her eyes and hold the arms perpendicular to the body with the palms up for 15 to 30 seconds.If there is a cerebral or brainstem reason for muscle weakness,the arm on the weak side will start to fall,or "drift"with the palm pronating (turning inward).This is called a pronation drift.The same can be done for the lower extremities,with the client lying on his or her stomach with the legs bent upward at the knees.However,it is easier for most clients to sit on the side of the bed and extend the legs outward.