**1.11 Coronary arteries and veins**

The right coronary artery from the sinus of Valsalva has an anterior direction in the epicardial layer and enters the right atrioventricular sulcus. The left coronary artery from the left sinus of Valsalva loops posteriorly to the pulmonary artery root, then exits anteriorly. The left main coronary artery bifurcates into the left anterior descending and left circumflex arteries. In a normal person, these arteries are usually only visible for the first 1–2 cm in the left sternal cross-section. Many cardiac veins drain into the right atrium. Most notable because ultrasound can be seen in the coronary sinus, a bulging vein that receives most of the cardiac veins before emptying into the right atrium. This sinus is about 2.5 cm long, enlarged, and located in the coronary sulcus at the back of the heart (**Figure 5**).
