Anatomically, lower extremity vessels are divided into lower extremity arteries and lower extremity veins, and common diseases are as follows: 1. Lower extremity arteries: common diseases include arterial stenosis or occlusion, and the causes include atherosclerosis, congenital dysplasia, inflammation, myofibrillar dysplasia or organismal immune diseases; 2. Lower extremity veins: common diseases include venous thrombosis, varicose veins, vascular malformations, etc., mostly related to autoimmune diseases or congenital dysplasia, and may also be related to hemangioma and lymphoma.