Aortic window
![A chest radiograph with the angle parts of the ribs and some other landmarks labeled.](/Images/godic/202412/21/Chest_labeled4358.png")
The aortic window is a normally radiolucent region below the aortic arch. It is formed by the bifurcation of the trachea and traversed by the left pulmonary artery. It is visible in the left anterior oblique radiograph of the heart and great vessels.