The Tunica Adventitia is the outermost layer of blood vessels, including arteries and veins. It is primarily composed of connective tissue, which provides structural support and flexibility. This layer helps anchor the blood vessels to surrounding tissues and organs, ensuring they remain in place within the body. In addition to connective tissue, the Tunica Adventitia contains nerves and small blood vessels known as vasa vasorum, which supply nutrients to the vessel wall itself. This layer plays a crucial role in maintaining the integrity and function of the vascular system, contributing to overall cardiovascular health.