Species range in size from the hefty Common Raven (Corvus corax), at 1.5 kg (3 lb 5 oz) and 70 cm (2 ft 3 in), to the diminutive Short-tailed Pygmy Tyrant (Myiornis ecaudatus), at just 4.2 g (0.14 oz) and 6.5 cm (2 Â½ in).
The heart receives its own supply of blood from the coronary arteries. Two major coronary arteries branch off from the aorta near the point where the aorta and the left ventricle meet. These arteries and their branches supply all parts of the heart muscle with blood.hen the coronary arteries narrow to the point that blood flow to the heart muscle is limited (coronary artery disease), collateral vessels may enlarge and become active.
The right coronary artery and the left coronary artery branch off the aorta (just after it leaves the heart) to deliver oxygen-rich blood to the heart muscle. These two arteries branch into other arteries, including the circumflex artery, that also supply blood to the heart.The cardiac veins collect blood from the heart muscle and empty it into a large vein on the back surface of the heart called the coronary sinus, which returns the blood to the right atrium.lood Supply of the Heart. Like all organs, the heart needs a constant supply of oxygen-rich blood. A system of arteries and veins, called the coronary circulation, supplies the heart muscle (myocardium) with oxygen-rich blood and then returns oxygen-depleted blood to the right atrium.