Heart Surface Anatomy with External Features
What is Heart?
Heart Surface Anatomy:
The heart presents the below external features:
- Three surfaces: Stern costal, diaphragmatic, and left.
- Three borders: Right, left, and inferior.
The Apex of the Heart:
- It is a conical area formed by the left ventricle.
- It is directed, forward and to the left in the 5th intercostal space.
- Location: It lies in the 5th intercostal space, about 9cm from the midline and slightly below and medial to the left nipple.
The Base of the Heart:
- The base (or posterior surface) of the heart is the most fixed part of the heart.
- It is formed by two atria: Two-thirds by the left atrium and one-third by the right atrium.
- The great veins enter the base of the heart- four pulmonary veins enter the left atrium, and superior and inferior venae cavae enter the right atrium.
The Surface of the Heart:
The surface of the heart has explained the below:
1. Sternocostal (or anterior) Surface:
- It is formed mainly by the right atrium and right ventricle which are separated from each other by the anterior part of the atrioventricular groove.
- It is also partly formed by the left auricle and left ventricle.
2. Diaphragmatic (or inferior) surface:
- This surface is flat and faces downward and backward.
- It is formed by the left ventricle (two-thirds) and right ventricle (one-third) which are separated from each other by the posterior interventricular groove.
3. Left Surface:
- It is directed upward, backward, and to the left.
- It is formed mainly by the left ventricle and partly by the left atrium and left auricle.
Borders of the Heart:
1. Right Border:
- Rounded and convex, formed only by the right atrium.
- It extends from the right side of the opening of the superior vena cava to that of the inferior vena cava.
- The right border separates the base from the stern coastal surface.
2. Left Border:
- It is formed mainly by the left ventricle and partly by the left auricle.
- It extends from the left auricle to the apex of the heart.
- It separates the stern coastal surface from the left surface.
3. Inferior Border:
- It is nearly horizontal and extends from the opening of the inferior vena cava to the apex of the heart.
- It separates the stern coastal surface from the diaphragmatic surface.