Anatomy of Heart and Pericardium

Fibrous Pericardium

• Related to the corresponding right and left lungs, pleura, and phrenic nerves
• Functions:
  • Maintains the central position of the heart within the chest
  • Prevents over-distension of the heart

Anterior Surface of Fibrous Pericardium

• Separated from the thoracic wall by the pleural membranes and the anterior edges of the lungs
• Bare area of pericardium:
  • Located at the cardiac notch, behind the lower part of the left half of the body of the sternum and the sternal ends of the left 4th to 6th costal cartilages
  • In direct contact with the thoracic wall without lung in between
  • Attached to the body of sternum by pericardio-sternal ligaments

Contents of Fibrous Pericardium

• Serous pericardium and its sinuses
• Heart and its blood supply
• Great vessels of the heart:
  • Ascending aorta
  • Pulmonary trunk
  • Lower 1/2 of SVC
  • Termination of IVC
  • Four pulmonary veins

Serous Pericardium

• A closed serous sac formed of two layers:
  • Visceral layer (epicardium of the heart)
  • Parietal layer:
    • Lines the inner surface of the fibrous pericardium
    • Reflected around the roots of the great vessels to become continuous with the visceral layer

Borders of the Heart

• Right border: formed by the right atrium, convex to the right
• Left border: formed by the left ventricle and the left auricle
• Lower border: formed by the right ventricle (mainly) and the left ventricle

Surface Anatomy of the Heart

• Surface anatomy of the sterno-costal surface of the heart is represented by points:
  • Point B: at Lt. 2nd c.c. (1 cm) from the sternum
  • Point A: at Rt. 3rd c.c. (1 cm) from the sternum
  • Point D: at Rt. 6th c.c. (1 cm) from the sternum
  • Point C (apex): at Lt. 5th intercostal space, (9 cm) to the left from the median plane
• Coronary groove: oblique line from Lt. 3rd to Rt. 6th sternocostal junctions

Pericardium Definition and Structure

• Definition: a fibro-serous sac that surrounds the heart and the proximal parts of the great vessels
• Structure:
  • Outer fibrous pericardium layer
  • Inner serous pericardium layer
• Extension: from 2 to 6 costal cartilages
• Shape: conical, having base, apex, and four surfaces (anterior, posterior, and two laterals)

Relations and Fixation of Pericardium

• Base: directed downwards, firmly attached to the central tendon of the diaphragm
• Apex: directed upwards, and fused with the outer coats of the great vessels
• Posterior surface: related to the posterior mediastinum and its contents, fused with the adventitia of the descending thoracic aorta

Pericardial Cavity

• Found between the visceral and parietal layers
• Contains a thin film of fluid
• Function of serous pericardium: responsible for lubrication of the heart, preventing friction during its movement

Pericardiocentesis

• Surgical puncture of the pericardial cavity for the aspiration of fluid
• Necessary to relieve the pressure of accumulated fluid on the heart in case of pericardial effusion

Pericardial Sinuses

• Transverse sinus:
  • A transverse passage lined by the serous pericardium
  • Situated between the ascending aorta and pulmonary trunk in front, and the superior vena cava, and pulmonary veins behind
  • Clinical significance: allows surgeons to isolate the pulmonary trunk and ascending aorta during cardiac surgery
• Oblique sinus:
  • A recess of the serous pericardium, lies behind the left atrium of the heart
  • Parietal layer of serous pericardium and fibrous pericardium separate the oblique sinus from the structures of the posterior mediastinum

Arterial Supply of Pericardium

• Fibrous pericardium and parietal layer of the serous pericardium:
  • Supplied by the pericardiacophrenic artery
  • Supplied by pericardial branches of the descending thoracic aorta