Left-right lateral projection of a 9 years old Saimiri sciureus showing the measurements of the length and height of the thoracic vertebrae (white lines) and sternebrae (black lines).The diameter of the aorta (red line) and caudal vena cava (blue line) are also presented. The angle of cardiac inclination is represented by the two white lines between the cranial border of the cardiac silhouette and the sternebrae.