Left margin

Left margin of heart
Sternocostal surface of heart.
Heart seen from above.
Details
Latin	Margo obtusus
Dorlands /Elsevier	m_04/12513824
Anatomical terminology []

The left margin of heart (or obtuse margin) is shorter than the right border of heart, full, and rounded: it is formed mainly by the left ventricle, but to a slight extent, above, by the left atrium.

It extends from a point in the second left intercostal space, about 2.5 mm. from the sternal margin, obliquely downward, with a convexity to the left, to the apex of the heart.

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)