The supine position (/ˈsuːpaɪn/) means lying horizontally with the face and torso facing up, as opposed to the prone position, which is face down. When used in surgical procedures, it grants access to the peritoneal, thoracic and pericardial regions; as well as the head, neck and extremities.[1]
Using anatomical terms of location, the dorsal side is down, and the ventral side is up, when supine.