The middle layer, the tunica media, is much thicker than the |tunica interna| and is composed of elastic filaments and |muscle fibers|. This layer is much thinner in |veins| than in arteries. It is the muscle coat, which gives the vessel its elasticity and contractility. This is necessary for the regulation of ~blood~ flow and the regulation of ~blood~ pressure. The larger vessels generally contain more elastic tissue than the smaller vessels.
