Human Anatomy
Heart and Pericardium
Heart and pericardium anatomy for MBBS: chambers, pericardial sinuses, coronary supply, conducting system and surface markings, mapped to NMC codes AN22.1 to AN22.7.
MedNext Academy | 3 min read
Heart and Pericardium
Heart and pericardium anatomy for MBBS: chambers, pericardial sinuses, coronary supply, conducting system and surface markings, mapped to NMC codes AN22.1 to AN22.7.
The heart and pericardium chapter builds the anatomical foundation that later cardiology and cardiac surgery depend on. It covers the chambers, the fibrous and serous pericardium and its sinuses, the coronary supply, the conducting system and the surface projection used at the bedside.
High-yield: Heart and Pericardium
- The left anterior descending artery supplies the anterior two-thirds of the interventricular septum; the posterior third comes from the posterior interventricular artery.
- The SA node is supplied by the right coronary artery in about 60% of people and by the left circumflex in the rest.
- The AV node is supplied by the right coronary artery in about 90% of people, from the AV nodal branch at the crux.
- Right-dominant circulation, seen in roughly 70% of people, means the posterior interventricular artery arises from the right coronary artery.
- The left anterior descending is the most commonly occluded coronary artery, producing an anterior wall infarct.
- Coronary arteries fill during diastole, not systole, so tachycardia reduces coronary perfusion time.
- The transverse pericardial sinus lies behind the aorta and pulmonary trunk and lets a surgeon clamp the great arteries.
- The oblique pericardial sinus is a blind cul-de-sac behind the left atrium, bounded by the pulmonary veins and inferior vena cava.
- The fibrous pericardium is attached to the central tendon of the diaphragm and blends with the adventitia of the great vessels.
- Pericardial pain is carried by the phrenic nerve, roots C3 to C5, and refers to the tip of the shoulder.
- The apex beat is normally in the left fifth intercostal space in the mid-clavicular line.
- Auscultation areas: mitral at the apex, tricuspid at the left lower sternal border, aortic at the right second space, pulmonary at the left second space.
- The right border of the heart is formed by the right atrium; the apex and left border are mainly the left ventricle.
- The coronary sinus drains most cardiac venous blood into the right atrium; the great cardiac vein runs with the left anterior descending artery.
- The moderator band carries the right bundle branch to the anterior papillary muscle of the right ventricle.
Coronary supply, at a glance
- **Right coronary artery:** SA node (about 60%), AV node (about 90%), right atrium and ventricle, inferior left ventricle in right-dominant hearts.
- **Left anterior descending:** Anterior interventricular septum, anterior and apical left ventricle. The most commonly occluded vessel.
- **Left circumflex:** Left atrium and the lateral and posterior left ventricle.
- **Dominance:** Set by which artery gives the posterior interventricular branch. Right-dominant in about 70% of people.
NMC competencies in this chapter
- **AN22.1:** External and internal features of the heart and its chambers
- **AN22.2:** Pericardium: structure, nerve supply and the pericardial sinuses
- **AN22.3:** Coronary arteries: origin, course, branches and anastomoses
- **AN22.4:** Anatomical basis of coronary dominance and ischaemic heart disease
- **AN22.5:** Conducting system of the heart
- **AN22.6:** Great vessels and their relations
- **AN22.7:** Surface projection of the heart and valves for auscultation
Frequently Asked Questions
Which coronary artery is most commonly blocked?
The left anterior descending artery. It supplies the anterior interventricular septum and the anterior and apical left ventricle, so its occlusion produces an anterior wall infarct.
What is coronary dominance?
Dominance is defined by which coronary artery gives off the posterior interventricular branch. About 70% of people are right-dominant, meaning the right coronary artery supplies it.
Why do the pericardial sinuses matter clinically?
The transverse pericardial sinus lets a surgeon pass a ligature around the aorta and pulmonary trunk during cardiac surgery, and the oblique sinus is where pericardial fluid can collect.
How does heart anatomy help in NEET-PG?
Coronary territories, the conducting system and valve surface markings recur in cardiology questions, so precise first-year anatomy transfers directly to PG preparation.
Continue reading
MBBSAll Human Anatomy chapters
Continue through the Human Anatomy chapter map.
Continue studying Human Anatomy
Explore clinician-written learning resources, structured revision and practice across the MedNext platform.
Open in the MedNext appSee plans