This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Physiology
If a patient experiences enlargement of the normally rudimentary central canal of the spinal cord in the MID cervical region, which, if any, muscular functions would become abnormal first? 
Select and explain. 
A. Finger flexion, B. Elbow flexion, C. Shoulder abduction, D. Truncal extension
C: Shoulder abduction
Answer: C: Shoulder abduction 
Explanation: Ans. C. Shoulder abductionMotor neurons controlling axial muscles are positioned most medially in the ventral horn area. An enlarged central canal would impinge on that pool of motor neurons first.