In obstruction of second pa of axillay aery, theanostomosis between the following aery will maintain the blood supply of upper limb:

Deep branch of transverse cervical aery & subscapular aery [Ref: BDC 4/e, Vol 1, p 56, 82; Snell's Clinical Anatomy 6/e, p 412-413, 657; Moore Clinical Anatomy 5/a, p 766-7671Axillary aery is the continuation of the subclan aery. It is crossed by pectoralis minor muscle which devides it into three pas.A rich anastomosis exists around the scapula between branches of subclan aery (first pa) & the axillary aery (third pa).This anastomosis provides a collateral circulation through which blood can flow to the limb when the distal pa of subclan aery or the proximal pa of axillary aery is blocked.Anastomosis around the scapula :Formed by branches of-Subclan aery - first pa- Suprascapular aery- Deep branch of transverse cervical aeryAxillary aery - third pa- Subscapular aery & its circumflex scapular branchThere are other smaller anastomoses over the acromion process, which also helps to maintain .flow to arm. (BDC Vol I, 4/e, p 82)Anastomoses over the acromion processFormed by -a)Acromial br. of thoraco-acromial aeryb)Acromial br. of suprascapular aeryc)Acromial br. of posterior circumflex humeral aeryThe subscapular aery also forms anastomoses with intercostal aeries