Question

what is the middle layer of an artery? I know three of them- tunica externa, tunica interna and lumen.

Answer 1

All arteries and veins contain three layers. The innermost layer is called the tunica intima. The muscular middle layer is called the tunica media, and the outermostlayer is called the tunica adventitia. Because capillaries are only one cell layer thick, they only have a tunica intima.