Please read the course note packet and the Neumann chapters 6 and 7 on the elbow and wrist to answer the following questions. You will find the Neumann text to be very helpful for this assignment.
Elbow and Wrist 1. At your home hold the end of a dowel or a cane in one hand while pronating and supinating the forearm. Make sure that your shoulder is fixed so that it cannot assist with the action. Analyze the movement and determine the following:
(a) When are the forearm supinators concentrically versus eccentrically active?
The supinators are concentrically active, shortened, from complete pronation to when the forearm is neutral. The supinators are eccentrically active, lengthened, from neutral to complete pronation (Neuman, 2002).
2. Why is elbow supination likely stronger with the elbow flexed to 90 degrees, rather than with the elbow in near full extension?…show more content… When the elbow is flexed to 90 degrees, supination torque may produce twice the torque than with the elbow is in full extension. This is due to the internal moment arm of the biceps brachii. At the 90 degree angle the tendon of the biceps nears a 90 degree angle of insertion into the radius. This allows the entire magnitude of a maximal effort biceps force. The biceps force is then multiplied by the estimated 1-cm internal moment arm available for supination and produces 500 Ncm of torque (Neuman, 2002).
Supination is weaker in full extension due to the decreased angle. A decreased angle will produce a decreased force that the biceps can use to supinate (Neuman, 2002).
3. Analyze the motion (at the wrist) of pounding a nail with a
