Posterior interosseous artery:
This vessel gains the extensor compartment by passing between the bones of the forearm above the interosseous membrane and below the oblique cord. It accompanies the posterior interosseous nerve and supplies the deep muscles of the extensor compartment. At the lower border of extensor indicis this small vessel is generally exhausted.
Anterior interosseous artery:
Distal to this level the arterial supply of the extensor compartment is furnished by the anterior interosseous artery, which pierces the interosseous membrane just above the upper border of pronator quadratus. The anterior interosseous artery then passes distally to end on the back of the wrist in the dorsal carpal anastomosis.