What position requires the patient to lie flat on his or her back?

The position that requires the patient to lie flat on his or her back is known as the supine position. In this position, the patient's face is directed upward, and the body is in a horizontal alignment. This position is commonly used during various medical examinations and procedures, as it provides easy access to the anterior part of the body and helps facilitate certain types of imaging, examinations, or surgeries.

The other positions mentioned serve different purposes. The prone position has the patient lying face down, which is often utilized for procedures involving the back or spine. The sitting position involves the patient being upright, providing an altered perspective on their physical state for examinations or relaxation. Fowler's position is characterized by the patient sitting partially upright, typically at an angle to aid with breathing or to enhance comfort. Each of these positions has specific applications, but the supine position distinctly denotes lying flat on the back.