The right margin of the heart (right border of heart) is long, and is formed by the right atrium above and the right ventricle below.
- The atrial portion is rounded and almost vertical; it is situated behind the third, fourth, and fifth right costal cartilages about 1.25 cm. from the margin of the sternum.
- The ventricular portion, thin and sharp, is named the acute margin; it is nearly horizontal, and extends from the sternal end of the sixth right coastal cartilage to the apex of the heart.
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)