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 from a public domain edition of Gray's Anatomy.