Anterior mediastinum

• Serous pericardium


  • Lines fibrous pericardium and coats the heart
  • Parietal layer lines the fibrous pericardium is reflected around the roots of great vessels to become continuous with the visceral layer
  • Visceral layer (Epicardium) closely applied to the heart
• Boundaries of the Mediastinum

  • Superiorly – superior thoracic aperture (thoracic inlet)
  • Inferiorly – diaphragm
  • Anteriorly – sternum and costal cartilages
  • Posteriorly – bodies of 12 thoracic vertebrae
  • Laterally (on each side), the mediastinal pleura
• Pericardium

  1. Encloses the heart and roots of great vessels

  2. Restricts excessive movements of the heart

  3. Serves as a lubricated container within which the heart can contract
• Nerve Supply to Pericardium

  • Fibrous pericardium is supplied by the Phrenic nerve
  • Serous pericardium (parietal layer) is supplied by the Serous pericardium
• Fibrous pericardium


  • Outermost fibrous part of the sac
  • Attached to Great Vessels, Central Tendon of Diaphragm, Sternum (Sterno-pericardial ligament)
• Pericardial cavity

  • Slit-like space between visceral and parietal layers
  • Contains about 50ml of pericardial fluid
  • Facilitates gliding movements (beating of the heart)
• Mediastinum

  • Occupied by the mass of tissue between the pulmonary cavities
  • Central compartment of the thoracic cavity
  • Contains all the thoracic viscera and structures except the lungs
• Subdivisions of Mediastinum

  • Superior mediastinum
  • Inferior mediastinum
  • Posterior mediastinum
  • Middle mediastinum
  • Anterior mediastinum
• Pericarditis is inflammation of the serous pericardium. Paracentesis / Pericardiocentesis is the aspiration of pericardial fluid from the pericardial cavity. Cardiac tamponade is the compression of the heart due to excessive accumulation of fluid within the pericardial cavity. Accumulation of pericardial fluid (e.g., pericarditis) or accumulation of blood (e.g., stab/gunshot wound of the heart) are applied aspects
• Pain from the parietal pericardium is carried in somatic afferent fibres in phrenic nerves. Therefore, pericardial-related pain may be referred to the supraclavicular region or lateral neck
• Nerve Supply to Pericardium

  Fibrous pericardium is supplied by the Phrenic nerve, serous pericardium (parietal layer) and serous pericardium (visceral layer) are supplied by Vagus nerve and Sympathetic trunk
• Pericardium


  Outer layer around the roots of great vessels, becomes continuous with the visceral layer
• Knowledge of structures forming the borders of the heart is essential for interpreting the cardiac shadow seen in radiographs
• Pericardial vessels & Nerves

  • Arteries: branches from the internal thoracic, pericardiacophrenic, musculophrenic, inferior phrenic and the thoracic aorta
  • Veins: pericardial veins drain into the azygos system of veins, the internal thoracic veins and superior phrenic veins
  • Nerves: the Vagus nerve, sympathetic trunks, and phrenic nerves
• Visceral layer (Epicardium)


  Closely applied to the heart
• Pericardial cavity

  Slit-like space between visceral and parietal layers, contains about 50ml of pericardial fluid, facilitates gliding movements (beating of the heart)
• Pericardial sinuses

  • Transverse pericardial sinus: lies posterior to the aorta and pulmonary trunk, lies anterior to the left atrium and superior vena cava
  • Oblique pericardial sinus: Inverted J-shaped blind sac bounded by IVC + 4 pulmonary veins, lies posterior to left atrium; anterior to the esophagus
• Anterior Interventricular sulcus separates the right and left ventricles. Posterior interventricular sulcus separates the right and left ventricles
• External features of the heart: Heart develops as a tubular structure near the sternum, which later becomes folded. Ventricles lie antero-inferior to the atria
• Inferior surface of right atrium also forms part of the surface of the heart
• Chambers of the Heart

  • RA
  • RV
  • LA
  • LV
• Left coronary artery arises from the left posterior aortic sinus of the ascending aorta
• Coronary Circulation

  • Right and Left coronary arteries
  • Right coronary artery
  • Left coronary artery
• In the region of the apex, the apex beat can be palpated in the patient
• Anterior Interventricular sulcus separates the right and left ventricles
• The apex of the heart is formed by the left ventricle
• Disorders of the Right coronary artery can lead to conditions like atherosclerosis, sinus bradycardia, AV nodal block, and SA node issues
• Right coronary artery branches include branches to the AV Node, SA Node, Right marginal branch, and Posterior interventricular branch
• Heart Sulci (Grooves)

  • Atrioventricular (Coronary) groove
  • Anterior interventricular groove
  • Posterior interventricular groove
• The apex of the heart lies at the level of the 5th left intercostal space, 9cm from the midline (just medial to midclavicular line)
• Posterior interventricular sulcus separates the right and left ventricles
• Right coronary artery descends along the right atrioventricular groove and continues posteriorly
• The base of the heart lies opposite the apex
• Left coronary artery supplies the major part of the heart and originates from the left posterior aortic sinus of the ascending aorta
• Heart Surfaces

  • LV
  • RV
  • RA
  • LA
• Right coronary artery supplies areas like the right atrium, portion of left atrium, right ventricle, interatrial septum, and posterior interventricular septum
• Right coronary artery arises from the anterior aortic sinus of the ascending aorta
• Post

  IV septum (+adjoining part of Lt.ventricle)
• Left coronary artery (LCA)


  • Larger than RCA, supplies the major part of heart
• Anterior interventricular branch of LCA


  Runs down in anterior IV groove to the apex of the heart