Muscular artery wall. Light micrograph of a section through part of the wall of a normal human femoral artery. This is a muscular artery with a thick wall that enables it to carry blood under pressure to the lower limb. This wall is composed of three layers. The innermost tunica intima surrounds the lumen which contains blood cells (top right). It possesses a fine elastic sheet (convoluted) known as the internal elastic lamina. The middle layer, the thick tunica media, is mainly composed of smooth muscle fibres (pink). The external tunica adventitia, mainly composed of connective tissue (green) supported by an elastic layer (brown).