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.