The Anatomy of the Heart

Overview of Heart Surfaces

• Anterior Surface: Front view
• Posterior Surface: Back view
• Inferior Surface: Bottom view
• Apex: Pointed lower tip
• Base: Part near the right shoulder

Main Structures on the Anterior Surface

• Auricles: Fatty pouches on atria
  • Left Auricle: Present on the left side
  • Right Auricle: Present on the right side

Major Arteries and Veins

• Pulmonary Trunk: Transports deoxygenated blood from the right ventricle to the lungs
• Aorta: Major artery carrying oxygenated blood
  • Ascending Aorta
  • Aortic Arch
    • Brachiocephalic Artery: Splits into right subclavian and right common carotid
    • Left Common Carotid Artery
    • Left Subclavian Artery
  • Descending Aorta: Turns into thoracic and then abdominal aorta

Right Side of the Heart

• Right Atrium: Receives deoxygenated blood
• Superior Vena Cava: Systemic vein dumping blood into the right atrium
  • Right Brachiocephalic Vein
  • Left Brachiocephalic Vein
• Azygos Vein: Connects to the superior vena cava

View from Posterior Side

• Right Pulmonary Artery: Carries deoxygenated blood to the right lung
• Left Pulmonary Artery: Carries deoxygenated blood to the left lung
• Pulmonary Veins: Carry oxygenated blood from the lungs to the left atrium
  • Left Pulmonary Veins
  • Right Pulmonary Veins
• Descending Aorta: Continuing from the thoracic to abdominal regions
• Azygos Vein: Drains into the superior vena cava

Coronary Circuit

• Right and Left Coronary Arteries: First branches from ascending aorta
  • Anterior Interventricular Artery (Left Anterior Descending Artery): Supplies anterior walls of ventricles and interventricular septum
    • Common site for myocardial infarction (~40%)
  • Circumflex Artery: Wraps around auricle, supplies lateral walls of left ventricle

Veins in Coronary Circuit

• Great Cardiac Vein: Accompanies the anterior interventricular artery
• Posterior Vein of Left Ventricle: Drains blood from myocardium on left ventricle's posterior side
• Small Cardiac Vein: Follows the right coronary artery's path
• Middle Cardiac Vein: Accompanies the posterior interventricular artery
• Coronary Sinus: Collects blood from various veins and dumps into the right atrium
  • Azygos Vein: Connects with the coronary sinus

Arterial Anastomoses (Collateral Circulation)

• Posterior Interventricular Artery and Marginal Artery: Form an anastomosis
• Circumflex Artery and Posterior Interventricular Artery: Form an anastomosis
• Anterior Interventricular Artery and Circumflex Artery: Form an anastomosis

Internal Structure of the Heart

• Atria and Ventricles
  • Right Atrium: Receives deoxygenated blood via superior vena cava
  • Left Atrium: Receives oxygenated blood via pulmonary veins
  • Right Ventricle: Pumps blood to pulmonary trunk
    • Tricuspid Valve: Between right atrium and right ventricle
    • Chordae Tendineae and Papillary Muscles: Support tricuspid valve
  • Left Ventricle: Pumps blood to aorta
    • Mitral (Bicuspid) Valve: Between left atrium and left ventricle
    • Aortic Semilunar Valve: Prevents backflow to left ventricle
• Interventricular Septum: Wall dividing left and right ventricles
  • Can have defects (e.g., Tetralogy of Fallot)

Specialized Muscle Structures

• Pectinate Muscles: Located in the atria walls
• Trabeculae Carneae: Located in ventricular walls
• Myocardium: Muscular wall of the heart
• Endocardium: Lines internal chambers and valves
• Epicardium: Outer layer of heart made of mesothelium

Fetal to Adult Circulation Changes

• Foramen Ovale: Turns into the fossa ovalis after birth
• Ductus Arteriosus: Turns into the ligamentum arteriosum after birth

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Major Learning Points:

• Familiarize with heart anatomy
• Understand location and function of key structures
• Recognize significance of coronary arteries and veins
• Acknowledge the importance of collateral circulation
• Grasp differences between fetal and adult heart circulation