Light microscopy of a muscular artery sectioned in an oblique plane. This is the most common type among arteries. Starting innermost the artery wall is formed by an internal elastic layer/lamina shown as a dark blue wavy line (part of the tunica intima). A wide smooth muscle layer (tunica media, green) and an outer but thinner connective tissue layer (green) called the tunica adventitia are separated by the external elastic lamina (dark blue wavy line). Muscular arteries serve to distribute and maintain blood flow to organs and tissues using their smooth muscle to control vessel diameter. Magnification x100 when printed at 10 cm.