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 of the following is least likely to be involved in a collateral anastomosis which bypasses an obstruction of the first pa of the axillary aery? 
Select and explain. 
A. Suprascapular aery, B. Subscapular Aery, C. Dorsalscapular Aery, D. Posterior humeral circumflex aery
D: Posterior humeral circumflex aery
Answer: D: Posterior humeral circumflex aery 
Explanation: The suprascapular, dorsal scapular, subscapular, and scapular circumflex aeries paicipate in a potential collateral anastomoses around the scapula. The suprascapular and dorsal scapular aeries arise, directly or indirectly, from the subclan aery while the subscapular and scapular circumflex aeries are from the third pa of the axillary aery, thus providing a bypass for obstructions of the first or second pas of the axillary aery.