Final answer:
The knee-chest position is the correct answer for lying prone with the head down, knees bent, and buttocks elevated. It is used for specific medical examinations and procedures to provide better access to certain body areas.
Step-by-step explanation:
The position achieved by lying prone with the head down, the knees bent, and buttocks elevated is known as the knee-chest position. This position is utilized in certain medical examinations and procedures, as it allows for better access and examination of particular body parts, such as during a sigmoidoscopy or during certain spinal adjustments.
In the knee-chest position, the patient rests on their knees and chest, with their buttocks in the air and their head and upper chest lowered to the floor or bed. This is different from the dorsal recumbent position (lying on the back), the lithotomy position (lying on the back with legs raised and feet in stirrups), the Sim’s position (lying on the side with the lower arm behind the body and the upper thigh bent), or the Trendelenburg position (supine with the body tilted so that the head is lower than the feet).