1) Structure

• 4 chambers: right atrium (RA), right ventricle (RV), left atrium (LA), left ventricle (LV).
• Valves:
  • RA → RV: tricuspid
  • RV → pulmonary trunk: pulmonary valve
  • LA → LV: mitral
  • LV → aorta: aortic valve
• Wall layers: endocardium, myocardium, epicardium (visceral pericardium).
• Great vessels: SVC/IVC to RA, pulmonary artery from RV, pulmonary veins to LA, aorta from LV.
  (From Harrison’s, p. 7407)

2) Relations

• Lies in middle mediastinum, obliquely behind sternum.
• Anterior: sternum, costal cartilages, lungs/pleura.
• Posterior (base): mainly LA, related to esophagus and descending thoracic aorta.
• Inferior: diaphragm (central tendon).
• Right border: RA.
• Left border/apex: mainly LV (apex in left 5th intercostal space, mid-clavicular line).
  (Standard gross anatomy; aligned with core heart anatomy references)

3) Blood supply

• Coronary arteries arise from aortic sinuses above aortic valve cusps.
  (Bailey & Love, p. 975)
• Right coronary artery (RCA): RA, most RV, part of LV inferior wall, often SA/AV nodes.
• Left coronary artery (LCA) divides into:
  • LAD: anterior LV wall, anterior septum, apex
  • LCx: lateral/posterior LV (varies by dominance)
• Venous drainage: coronary sinus → RA (plus anterior cardiac veins, Thebesian veins).

Diagram