This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen: Miscellaneous, Subject name: Anatomy
Most common site of subclan aery stenosis is in pa: 
Select and explain. 
A. 1st, B. 2nd, C. 3rd, D. Terminal
A: 1st
Answer: A: 1st 
Explanation: Subclan Aery is most commonly obstructed in the proximal poion -1st pa proximal to the origin of veebral and internal thoracic aery. It is focal and is usually an extension of atherosclerotic narrowing from the aoic arch into the aery. The stenosis is more common on left side - Left subclan is involved 3 times more frequently involved than the right.