What is the middle layer of an artery and vein?

Step-by-step solution

The blood flows strictly by a fixed route through Blood Vessels—the arteries and veins. Basically, each artery and vein consists of three layers: an inner lining of squamous endothelium, the tunica intima , a middle layer of smooth muscle and elastic fibres, the tunica media , and an external layer of fibrous connective tissue with collagen fibres, the tunica externa. The tunica media is comparatively thin in the veins .