National Physical Therapy Examination (NPTE) Practice Exam

During right forearm supination, how does the radial head move at the proximal radioulnar joint?

1. Roll and slide posteriorly

2. Roll anteriorly and slide posteriorly

3. Roll posteriorly and slide anteriorly

4. Roll and slide anteriorly

The correct answer is: Roll posteriorly and slide anteriorly

In forearm supination, which is the motion that turns the palm of the hand to face upward or forward, the radial head undergoes specific movements at the proximal radioulnar joint. During this motion, the radial head primarily rolls posteriorly while simultaneously sliding anteriorly. This occurs due to the orientation of the bones and the mechanics of the joint as the radius is moving into supination. As the forearm moves from a pronated position to a supinated position, the radial head rotates around the stationary ulna, causing it to roll in a backward direction while also translating forward. This combined motion allows the arm to transition smoothly into a supinated position without complications. Recognizing that movements in the joints are not solely based on rolling or sliding in isolation is crucial. The radial head's complex movement incorporates both types of motion to maintain proper function and alignment of the forearm. Understanding this will aid in recognizing how the effectiveness of various therapeutic interventions can benefit patients with forearm restrictions or injuries.