Final answer:
The purpose of using a pad (towel) under the distal humerus during goniometric measurement of elbow flexion is to provide support and stabilization.
Step-by-step explanation:
The purpose of using a pad (towel) under the distal humerus during goniometric measurement of elbow flexion is to provide support and stabilization. The pad helps to ensure that the elbow is positioned in a consistent and accurate manner for measurement. It also helps to minimize any discomfort or pressure on the bony prominences of the elbow, allowing for a more comfortable and reliable measurement.