Source:http://linkedlifedata.com/resource/umls/id/C0182293
UMD: Pillows that are shaped to conform to the natural curvature of the neck, which promotes correct head and neck positioning in patients sleeping on their back or side and prevents interference from the shoulder and upper arm in patients sleeping on their side. They usually are rectangular with one or more sides thicker than the center. Some are crescent-shaped to wrap around the neck; others are the shape of a standard pillow but are filled with gel, water, or air (inflatable) so as to conform to the natural curvature of the neck.