Anatomy of the Heart

General Overview

• The heart is a muscular organ, about the size of a clenched fist.
• Located in the thorax between the lungs in an area called the mediastinum.
• Enclosed by a membrane called the pericardium.
• Functions to pump oxygen-rich blood to the body and send oxygen-poor blood to the lungs.

Structure of the Heart

• Composed of four chambers:
  • Right Atrium and Right Ventricle (Right Heart)
  • Left Atrium and Left Ventricle (Left Heart)
• Each atrium has pouch-like protrusions called auricles.

Blood Circulation

• Right Atrium: Receives deoxygenated blood from the body via the superior and inferior vena cava.
• Right Ventricle: Pumps blood into the pulmonary trunk towards the lungs (pulmonary circulation).
• Left Atrium: Receives oxygenated blood from the lungs via four pulmonary veins.
• Left Ventricle: Pumps blood into the aorta (systemic circulation).

Heart's Shape and Orientation

• The heart is pyramid-shaped with a base and an apex.
• Borders of the Heart:
  • Superior: Right and left atria.
  • Inferior: Right ventricle and part of the left ventricle.
  • Right: Right atrium.
  • Left: Left ventricle and part of the left auricle.

Heart Valves

• Tricuspid Valve: Located between the right atrium and right ventricle; has three cusps.
• Pulmonary Valve: Semilunar valve between the right ventricle and pulmonary trunk.
• Mitral Valve: Located between the left atrium and left ventricle; bicuspid.
• Aortic Valve: Semilunar valve between the left ventricle and aorta.

Coronary Circulation

• Blood supply via coronary arteries originating from the aortic sinuses.

Conducting System of the Heart

• Sinoatrial (SA) Node: Pacemaker located at the junction of the superior vena cava and right atrium.
• Atrioventricular (AV) Node: Located in the interatrial septum.
• AV Bundle (Bundle of His): Divides into right and left branches, spreading impulses to ventricles.

Innervation

• Sympathetic and Parasympathetic Innervation:
  • Sympathetic: Increases heart rate and contraction force.
  • Parasympathetic (via vagus nerve): Slows heart rate.
• Nerve fibers run along the coronary vessels and conducting system.

Clinical Relevance

• Heart Appearance on X-ray: Right atrium and left ventricle visible as the heart silhouette.
• Important Structures in Imaging:
  • Coronary sulcus (atrioventricular groove)
  • Anterior and posterior interventricular sulcus
  • Great vessels orientation

Summary

• The heart is critical for systemic and pulmonary circulation, maintained by coordinated contractions and efficient valve systems.
• Nodal tissue provides the intrinsic electrical impulses necessary for heart function.