What are the three layers of the arterial wall?

The three layers of the arterial wall consist of the tunica intima, tunica media, and tunica externa. The tunica intima is the innermost layer, which provides a smooth lining for the blood vessels and minimizes resistance to blood flow. This layer primarily consists of endothelial cells and a subendothelial layer of connective tissue.

The tunica media is the middle layer and is typically the thickest layer in arteries. It is primarily composed of smooth muscle and elastic fibers, which allow arteries to constrict and dilate in response to changes in blood pressure and flow. This elasticity is crucial for maintaining blood pressure and regulating blood flow throughout the circulatory system.

The tunica externa, also known as the adventitia, is the outermost layer of the arterial wall. It is mainly made of connective tissue and provides structural support and stability to the artery, anchoring it to surrounding tissues and organs.

The other options do not correctly represent the recognized layers of the arterial wall. For instance, mentioning a "layer of collagen" or "vascular layer" may refer to components found within the layers but does not accurately denote the three distinct layers recognized in vascular anatomy.