Anatomy of the Heart

Overview

• The heart is composed of four hollow chambers:
  • Two superior smaller atria
  • Two inferior larger ventricles
• Auricles: Flap-like extensions of atria resembling ears

External Structures

• Atria: Marked by auricles
  • Right atrium feeds the right ventricle
  • Left atrium feeds the left ventricle
• Ventricles:
  • Right ventricle feeds into pulmonary trunk and pulmonary circulation
  • Left ventricle feeds the aorta and systemic circulation
• Sulci:
  • Coronary sulcus: Separates atria from ventricles
  • Interventricular sulcus: Separates left and right ventricles
• Great Vessels:
  • Superior and inferior vena cava: Bring deoxygenated blood to right atrium
  • Pulmonary trunk: Exit from right ventricle to pulmonary circulation
  • Pulmonary veins (right and left): Bring oxygenated blood from lungs to left atrium
  • Aorta: Blood exits from left ventricle to systemic circulation

Internal Structures

• Valves: Ensure one-way blood flow
  • Atrioventricular (AV) valves: Between atria and ventricles
    • Right AV valve (Tricuspid valve)
    • Left AV valve (Bicuspid/Mitral valve)
  • Semilunar valves: At exits of ventricles
    • Pulmonary semilunar valve (Right ventricle to pulmonary trunk)
    • Aortic semilunar valve (Left ventricle to aorta)
• Heart Sounds: "Lubb-dupp"
  • "Lubb": Closure of AV valves
  • "Dupp": Closure of semilunar valves

Chamber Details

• Right Atrium:
  • Receives deoxygenated blood from systemic circulation
  • Contains pectinate muscles (internal ridges)
  • Right AV valve ensures flow to right ventricle
• Right Ventricle:
  • Receives blood from right atrium
  • Contains interventricular septum and trabeculae carneae
  • Papillary muscles anchor chordae tendineae
  • Pulmonary semilunar valve ensures flow to pulmonary trunk
• Left Atrium:
  • Receives oxygenated blood from pulmonary veins
  • Contains pectinate muscles
  • Left AV valve ensures flow to left ventricle
• Left Ventricle:
  • Pumps blood through systemic circuit
  • Thick myocardium (three times thicker than right)
  • Contains trabeculae carneae, papillary muscles, chordae tendineae
  • Aortic semilunar valve ensures flow to aorta

Blood Flow Pathway

1. Deoxygenated blood enters right atrium via venae cavae or coronary sinus
2. Through tricuspid valve to right ventricle
3. Through pulmonary semilunar valve to pulmonary trunk and lungs
4. Oxygenated blood returns via pulmonary veins to left atrium
5. Through bicuspid valve to left ventricle
6. Through aortic semilunar valve to aorta and systemic circulation

Key Functions and Terms

• Chordae Tendineae: Fibrous cords anchoring AV valves
• Papillary Muscles: Anchor chordae tendineae
• Interventricular Septum: Separates ventricles, prevents blood mixing
• Pectinate Muscles: Found in atria, ridged internal surface
• Trabeculae Carneae: Irregular muscular ridges in ventricles
• Importance: Understanding these structures and functions is crucial as it forms the basis for more advanced concepts in heart anatomy and function.