The pectoral girdle has a rich plexus of arterial vessels that anastomose around the scapula and its muscles known as the scapular anastomosis. It functions to allow blood to flow around the scapular and shoulder joint if there is injury or occlusion. Contributing branches arise from as proximal as the first part of the subclavian arterial to as distal as the third part of the axillary artery. The branches that contribute include:
- transverse cervical artery (from the thyrocervical trunk) descends down the medial border of the scapula to its inferior angle
- suprascapular artery (from the thyrocervical trunk or third part of the subclavian artery) passes through the supraspinous fossa, around the lateral border of the scapular spine and into infraspinous fossa down to the inferior angle
- subscapular artery (from the from the third part of the axillary artery) passes through the subscapularis muscle in the subscapular fossa down to the inferior angle
Accompanying veins also form a rich venous plexus.