21.4 Orientation and Superficial Anatomy of the Heart

• • The heart sits slightly to the left of the midline within the mediastinum. The heart is rotated to the left, causing the right atrium and the right ventricle to be located more anteriorly within the thoracic cavity than the left atrium and left ventricle.
• The heart

  • lies slightly to the left of midline
  • sits at angle to longitudinal axis of body
  • rotated to left
• The base of the heart is the broad, superior portion of the heart, where it is attached to the major arteries and veins of the systemic and pulmonary circuits
• The apex of the heart is the inferior, pointed tip of the heart and is formed mainly by the left ventricle
• The base forms the superior border of the heart
• The right border of the heart is formed by right atrium
• The left ventricle and a small portion of the left atrium form the left border
• The left border extends to the apex, where it meets the inferior border
• The anterior surface or sternocostal surface, of the heart faces the anterior thoracic wall and consists mostly of the wall of the right ventricle and some of the left ventricle
• The posterior surface, at the base, is formed by the left atrium and a small portion of the right atrium
• The diaphragmatic surface of the heart is composed mainly of the posterior, inferior surfaces of the right and left ventricles
• External grooves, of sulci, of the heart show the borders of four internal chambers of heart
• A shallow interatrial groove separates the two atria
• The deeper coronary sulcus marks the border between the atria and ventricles
• On the anterior surface the anterior interventricular sulcus separates the left and right ventricles
• The posterior interventricular sulcus separates the left and right ventricles on the posterior surface
• The atria receive venous blood that continous flowing into the ventricles
• The ventricles propel blood to the peripheral tissues and the lings
• The anterior portions of each atrium deflates and becomes a rather lumpy and wrinkled flap called an auricle
• SUMMARY

  • Great vessels are connected to superior end of heart at base. Inferior pointed tip of heart is apex
  • Heart sits at angle to longitudinal axis of body and presents following borders: superior, inferior, left, and right
  • Heart has: anterior surface of sternocostal surface of heart faces anterior thoracic wall and consists mostly of wall of right ventricle and some of left ventricle. The posterior surface at base is formed by left atrium and small portion of right atrium. Diaphragmatic surface of heart is composed mainly of posterior, inferior surfaces of right and left ventricles
• SUMMARY

  • Division of heart into four chambers produces external landmarks that are grooves or sulci on surface of heart. Interatrial groove separates two atria, while coronary sulcus separates atria from ventricles. Other shallow depressions include anterior interventricular sulcus and posterior interventricular sulcus
  • Auricle (atrial appendage) is an expandable extension of atrium