Which layer is the outermost layer of arteries?

Which layer is the outermost layer of arteries?

• A. Tunica externa
• B. Tunica intima
• C. Tunica media
• D. Endothelium

Answer: (A)

Arteries have concentric wall layers that run from inside to outside, with the outermost layer specialized for support and anchoring the vessel to surrounding tissues. This outer layer is the tunica externa (also called the adventitia). It is primarily connective tissue with collagen fibers, providing structural stability, and in larger arteries may contain small vessels (vasa vasorum) to nourish the vessel wall itself. Inside this, the next layer is the tunica media, the muscular layer that contains smooth muscle and elastic fibers to regulate vessel diameter and blood pressure. The innermost lining is the tunica intima, which includes the endothelial cells lining the lumen; the endothelium is the inner surface of this tunica intima. So the outermost layer is the tunica externa.

Arteries have concentric wall layers that run from inside to outside, with the outermost layer specialized for support and anchoring the vessel to surrounding tissues. This outer layer is the tunica externa (also called the adventitia). It is primarily connective tissue with collagen fibers, providing structural stability, and in larger arteries may contain small vessels (vasa vasorum) to nourish the vessel wall itself.

Inside this, the next layer is the tunica media, the muscular layer that contains smooth muscle and elastic fibers to regulate vessel diameter and blood pressure. The innermost lining is the tunica intima, which includes the endothelial cells lining the lumen; the endothelium is the inner surface of this tunica intima.

So the outermost layer is the tunica externa.