Layers of a vessel

By BruceBlaus. When using this image in external sources it can be cited as:Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=28761794
In this image, all three layers of the artery are seen. The tunica intima, tunica media and tunica externa. The tunica media is made of smooth muscle, contracting with the impulse by the nervous system.