Which statement lists the layers of an artery from inner to outer?

Which statement lists the layers of an artery from inner to outer?

• A. Tunica intima, tunica media, tunica externa
• B. Endothelium and basement membrane only
• C. Tunica adventitia and tunica externa
• D. Visceral and parietal layers

Answer: (A)

Arteries have three concentric layers arranged from the inside out: the tunica intima, tunica media, and tunica externa. The innermost tunica intima is lined by the endothelium and its basement membrane, sometimes with an internal elastic membrane in arteries. The middle layer, tunica media, is mainly smooth muscle with elastic fibers that allow the vessel to constrict or dilate. The outer layer, tunica externa (also called adventitia), is connective tissue that anchors the vessel in place. This makes the correct inner-to-outer sequence tunica intima, tunica media, tunica externa. The other options don’t fit because: focusing only on the endothelium and basement membrane omits the middle muscular layer and outer connective tissue; duplicating the outer layer as both adventitia and externa leaves out the inner layers; and visceral vs. parietal layers refer to serous membranes, not arterial wall layers.

Arteries have three concentric layers arranged from the inside out: the tunica intima, tunica media, and tunica externa. The innermost tunica intima is lined by the endothelium and its basement membrane, sometimes with an internal elastic membrane in arteries. The middle layer, tunica media, is mainly smooth muscle with elastic fibers that allow the vessel to constrict or dilate. The outer layer, tunica externa (also called adventitia), is connective tissue that anchors the vessel in place. This makes the correct inner-to-outer sequence tunica intima, tunica media, tunica externa.

The other options don’t fit because: focusing only on the endothelium and basement membrane omits the middle muscular layer and outer connective tissue; duplicating the outer layer as both adventitia and externa leaves out the inner layers; and visceral vs. parietal layers refer to serous membranes, not arterial wall layers.