This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Which one of the following has maximum area of representation in the cerebral motor coex? 
Select and explain. 
A. Shoulder joint, B. Elbow joint, C. Wrist joint, D. First Metacarpophalangeal joint
D: First Metacarpophalangeal joint
Answer: D: First Metacarpophalangeal joint 
Explanation: First Metacarpophalangeal joint REF: Gray's anatomy, 39' edition page 396The primary motor coex contains a detailed topographically organized map (motor homunculus) of the opposite body half, with the head represented most laterally, and the legs and feet represented on the medial surface of the hemisphere in the paracentral lobule. A striking feature is the dispropoionate representation of body pas in relation to their physical size. Thus, large areas represent the muscles of the hand and face, which are capable of finely controlled or fractionated movements.