Final answer:
The distal radioulnar joint consists of the head of the ulna and the ulnar notch of the radius, which work together to enable rotational movements of the forearm such as supination and pronation.
Step-by-step explanation:
The distal radioulnar joint is one of the pivotal points that allows for the rotation of our forearm, facilitating movements such as pronation and supination. Specifically, this joint is made up of the head of the ulna and the ulnar notch of the radius. These structures allow the hand to rotate around the forearm, which is evident when you perform actions like turning a doorknob or using a screwdriver.
In the anatomical position, with your palms facing forward, supination allows your arm to maintain this position or turn the palm upwards—as if you were scooping soup—while pronation would turn the palm downwards or backwards. The unique structure of the distal radioulnar joint, including the way in which the radius crosses over the ulna, is integral to these movements.