The main forearm arteries are the radial artery, ulnar artery and common interosseous artery, as well as the superficial palmar arch and deep palmar arch that are subdivided into the hand. Injury to the forearm artery is mainly characterized by partial blockage of the blood supply to the hand, including weakness and loss of pulsation of the ulnar or radial artery, cold sensation in the fingers, skin irritation and numbness. An arterial patency test is an ancillary test used to check for proper arterial vascularity. The blood of the hand is supplied by two arteries, the ulnar artery and the radial artery, and there are abundant anastomotic branches between them, so when one of the arteries is occluded, the blood supply of the hand can still be ensured. This test is to observe the color change of the skin of the hand after blocking the radial artery to determine whether the blood flow of the ulnar artery is unobstructed. The corresponding signs of disease can be determined by the above method of examination. Pre-examination contraindications: Maintain a normal diet and sleep. Requirements during the examination: 1. Do not compress the vein at the same time when pressing the radial artery. 2.This test cannot diagnose the cause of vascular obstruction.