Cardiovascular System: The Heart

Introduction

The heart is a muscular organ essential for pumping blood throughout the body, ensuring the delivery of oxygen and nutrients to tissues and the removal of waste products. It is a central component of the cardiovascular system, which also includes blood vessels such as arteries, veins, and capillaries.

• Heart Function: The heart pumps approximately 1 million gallons of blood per year.

• Vascular Network: The cardiovascular system contains over 60,000 miles of blood vessels.

Heart Location

Mediastinum

The heart is located in the mediastinum, a central compartment in the thoracic cavity.

• Boundaries: The mediastinum extends from the sternum (anteriorly) to the vertebral column (posteriorly) and is situated between the lungs.

• Position: The heart lies posterior to the sternum and anterior to the esophagus and vertebral column.

• Landmarks: The heart is positioned near the sixth thoracic vertebra.

Additional info: The mediastinum also contains other vital structures such as the trachea, esophagus, and major blood vessels.

Heart Orientation

External Features and Anatomical Position

The heart is not positioned vertically in the chest; instead, it is slightly tilted and rotated.

• Apex: Directed anteriorly, inferiorly, and to the left. The apex is the pointed end of the heart, formed mainly by the left ventricle.

• Base: Directed posteriorly, superiorly, and to the right. The base is the broad, flat portion of the heart, formed mainly by the left atrium.

• Anterior Surface: Lies deep to the sternum and ribs.

• Inferior Surface: Rests on the diaphragm.

• Right Border: Faces the right lung.

• Left Border (Pulmonary Border): Faces the left lung.

Additional info: The orientation of the heart is clinically important for procedures such as auscultation, imaging, and surgery.

Key Terms

• Mediastinum: The central compartment of the thoracic cavity.

• Apex: The pointed, inferior tip of the heart.

• Base: The broad, superior portion of the heart.

Example: Surface Anatomy

• The apex of the heart is typically located at the fifth intercostal space, about 9 cm from the midline, which is a key landmark for auscultation of the mitral valve.