Surfaces and Borders

The apex of the heart is formed by:

• Tip of the left ventricle, which points inferiorly, anteriorly and to the left.

The sternocostal (anterior) surface is formed by:

• Right ventricle
  
  
• Right atrium
  
  
• Left ventricle
  
  
• Left atrium lie more posteriorly, and form only a small strip on the sternocostal surface.

The diaphragmatic (inferior) surface

• It is formed by both ventricles (mainly the left).
  
  
• Separated from the liver and stomach by the diaphragm on which it rests.
  
  
• Divided by the posterior interventricular groove or sulcus into a right one third, and a left two-third.
  
  
• This sulcus contains the posterior interventricular artery .

The base of the heart (posterior surface ), is formed by:

• The atria, mainly the left one.

The ascending aorta, the pulmonary trunk and the superior vena cava emerge from it

Notice at this point that the heart does NOT rest on its base; the term ‘base' derives from the conical shape of the heart, the base being opposite the apex .

The heart has four borders:

(a) The right border (R) is formed by the right atrium and is in line with the superior and inferior vena cavae.

(b) The inferior border (I) , thin and sharp, nearly horizontal. It is formed mainly by the right ventricle, and slightly by the left ventricle near the apex.

(c) The left border (L) , formed by the left ventricle and very slightly by the left auricle.

(d) The superior border (S) is where the great vessels enter and leave the heart. It is formed by both atria.