The Posterior Interosseous Artery (Dorsal Interosseous Artery; a. interossea dorsalis) passes backward between the oblique cord and the upper border of the interosseous membrane.
It appears between the contiguous borders of the Supinator and the Abductor pollicis longus, and runs down the back of the forearm between the superficial and deep layers of muscles, to both of which it distributes branches.
Where it lies upon the Abductor pollicis longus and the Extensor pollicis brevis, it is accompanied by the dorsal interosseous nerve.
At the lower part of the forearm it anastomoses with the termination of the volar interosseous artery, and with the dorsal carpal network. It gives off, near its origin, the interosseous recurrent artery, which ascends to the interval between the lateral epicondyle and olecranon, on or through the fibers of the Supinator, but beneath the Anconæus, and anastomoses with the radial collateral branch of the profunda brachii, the posterior ulnar recurrent and the inferior ulnar collateral.