Heart LO2

2.) Describe the external features of the heart, including which chambers of the heart compose the surfaces and borders.

There are 4 borders of the heart:

  • Right border: portion of the heart located between the superior and inferior venae cavae
    • Formed by R. atrium
  • Left border (obtuse margin): formed predominantly by the L. ventricle with a small contribution from the L. auricle of the L. atrium
  • Superior (upper) border: formed by the R. and L. atria
    • This border is important in terms of the close relationship to large vascular structures, such as the ascending aorta, pulmonary trunk, and superior vena cava
  • Inferior border (acute margin): formed predominantly by the R. ventricle with a contribution from the L. ventricle

There are 6 surfaces or aspects of the heart, including the apex and base:

  • Sternocostal (anterior) surface: formed predominantly by the R. ventricle with small contributions from the R. atrium & L. ventricle
    • The coronary & anterior interventricular sulci are visible on this surface
  • Apex of the heart: formed by the L. ventricle
    • Often considered as anteriorly facing and directed to the left
    • Located near the L. midclavicular line, just deep to the L. 5th intercostal space
  • Right surface: formed by R. atrium
  • Left surface: formed mainly by the L. border of the heart
  • Diaphragmatic (inferior) surface: formed mainly by the L. ventricle and portions of the R. ventricle
    • Very closely associated with the diaphragm
  • Base of heart (posterior aspect of heart): formed predominantly by the L. atrium with some contribution from the R. atrium
    • Closely associated with the pulmonary vv. & oblique pericardial sinus
    • Often considered as posteriorly facing and directed more to the right

There are 3 sulci (grooves) of the external heart that are superficial artifacts of the divisions/walls of the heart:

  • Coronary (atrioventricular) sulcus: sulcus between the atria and ventricles
    • Contains the coronary sinus, R. & L. coronary aa., main trunks
  • Anterior interventricular (IV) sulcus: sulcus between the ventricles; continuous with posterior interventricular sulcus
    • Located on sternocostal (anterior) surface
    • Anterior interventricular br. (left anterior descending - LAD) of L. coronary a. & great cardiac v. are located in this sulcus
  • Posterior interventricular (IV) sulcus: sulcus between the ventricles; continuous with the anterior interventricular sulcus
    • Located mostly on the diaphragmatic surface
    • Posterior interventricular br. (posterior descending a.) of R. coronary a. & middle cardiac v. are located in this sulcus