The Aorta: Very Basic Anatomy

The aorta is the main artery leading out from the left ventricle of the heart muscle. Its purpose is to deliver oxygenated blood to the body s tissues, having received oxygenated blood from left ventricle, via the left atrium, via the pulmonary veins. If we were to look at a cross section of the aorta, we would see concentric tissue rings similar to the rings of a tree trunk. There are three main muscular layers of the blood vessel starting on the outside, we have the tunica adventitia , then the tunica media and the innermost muscular layer is the tunica intima . Lining the tunica intima is the endothelium, a thin layer of cells which interact with the blood which flows through the true lumen of the aorta (similar to how water flows through a hosepipe). The aorta loops up ( ascending aorta ) and around the back of the heart muscle (into the descending aorta which serves the trunk and lower limbs), with the initial loop known as the aortic arch there are three main vessels which exit from this arching structure. The first of these vessels is called the brachiocephalic trunk ( brachio- = arms cephalic- = head), which shortly bifurcates into the right subclavian artery ( subclavian meaning under the clavicle this artery goes under the collar bone to supply the right upper limb with blood) and the right carotid artery (which supplies the brain). The second vessel of the aortic loop is the left carotid artery, also supplying the brain with blood. The third and final vessel of the aortic arch is the left subclavian artery, supplying the left upper limb. The descending aorta possesses many branched blood vessels which supply target organs and tissues with oxygenated blood. Common pathologies of the aorta include aortic aneurysm, in which there is an abnormal bulge of this major blood vessel, and aortic dissection, in which the tunica intima and tunica media muscular tissue layers become separated by an abnormal influx of blood, creating a dangerous false lumen .