Heart anatomy

• The 3 branches off the aorta are the brachiocephalic, left common carotid and the left subclavian
• The superior surface of the heart is known as the base
• The base of the heart is located at the 3rd costal cartilage
• The apex of the heart is located between the 4th and 5th costal cartillages
• The right side of the heart is deflected anteriorly, and the left side is deflected posteriorly.
• The slight deviation of the apex to the left is reflected in a depression in the medial surface of the inferior lobe of the left lung, called the cardiac notch.
• A typical heart is aprox 12cm in length
• The pulmonary arteries transport deoxygenated blood to the lungs (splits into 2 branches) and the pulmonary veins carry oxygenated blood back to the left atrium (4 in number)
• Each atria contains an auricle which can fill with blood and empty into the atria
•  From superficial to deep, these are the epicardium, the myocardium, and the endocardium
• Septa of the heart are physical extensions of myocardium
• The interatrial septum contains the fossa ovalis. This was previously known as the foramen ovale which shunts blood from the right to left atria directly to the left ventricle
• The tricuspid valve is located between the right A/V and the bicuspid valve is located between the left A/V.
• The right atrium contains the coronary sinus
• The right atrium and auricle contains pectinate muscles, whereas only the left auricle also contains these structures
• The chordinae tendinae are connective tissue which connect the valves to the papillary muscle
• Ventricle walls are lined with trabeculae carnae
• The moderator band is found in the right ventricle and plays a role in cardiac conduction
• The main branches of the left coronary artery are

  • Left circumflex artery
  • Left anterior descending artery
• The main branches of the right coronary artery are

  • Marginal artery
  • Right posterior descending artery
• The right coronary artery also supplies the hearts conduction system
• The main vein of the heart is the great cardiac vein, this lies parallel to the anterior descending artery
• All the veins drain into the coronary sinus where blood is drained into the right atrium
• The anterior cardiac veins drain directly into the right atrium
• Conduction system steps

  • SA node
  • AV node
  • Bundle of His
  • Purkinje Fibres
• The SA node is located in the superior part of the right atrium (near superior vena cava) and acts as the pacemaker
• The AV node is located in the inferior section of the right atrium. Here, there is a pause which allows atria to fully contract before signal reaches ventricles
• The Bundle of His travels down the interventricular septum. The right branch connects to the moderator band which supplies the right papillary muscles
• Purkinjie fibres extend from the apex and enable contract from the apex to spread up to the base