Light microscopy of a muscular artery. This is the most common type among arteries. Starting innermost is the internal elastic layer/lamina (part of the tunica intima) showing folding due to vessel contraction when fixed for histology. Next is a wide smooth muscle layer (tunica media) and an outer thinner connective tissue layer with some elastic fibres called the tunica adventitia. Muscular arteries serve to distribute and maintain blood flow to organs and tissues using their smooth muscle to control vessel diameter. Magnification x180 when narrow width printed at 10 cm.