Arterial Wall Layers

Steps:

• Recall arteries consist of three layers: tunica intima (inner), tunica media (middle), and tunica adventitia (outer).
• Identify tunica intima as a thin endothelium of simple squamous epithelial cells.
• Note tunica media contains smooth muscle cells and elastic fibers for contraction and recoil.
• Confirm tunica adventitia as connective tissue with collagen fibers and some elastic fibers for support.

Why C is correct:

• It matches the standard histological definition of arterial layers: endothelium of squamous cells (intima), smooth muscle and elastic fibers (media), elastic and collagen fibers (adventitia).

Why the others are wrong:

• A: Includes collagen in the middle layer, but media primarily has smooth muscle and elastic fibers, not collagen.
• B: Describes inner layer as smooth muscle, but endothelium consists of squamous epithelial cells, not muscle.
• D: Omits elastic fibers from middle and outer layers; middle needs elastic fibers, and outer includes both collagen and elastin.

Final answer: C