Explore the structure and function of the human heart, including the four chambers, valves, major blood vessels, and the conduction system.
Anatomy of the Heart – Study Notes
1. Overview
- Location: Mediastinum, between the lungs; sits behind the sternum, slightly left of mid‑line.
- Orientation: Apex points inferolaterally (≈5 cm below the left fifth intercostal space); base faces posteriorly toward the vertebrae.
- Size & Weight: Roughly the size of a closed fist; ~250–350 g in adults (larger in males).
2. External Features
| Structure |
Description |
Clinical Relevance |
| Pericardium |
Fibrous sac (outer) + serous pericardium (parietal & visceral layers). Contains ~15 mL serous fluid. |
Protects heart, limits over‑distension, reduces friction. |
| Apex (Tip) |
Pointed inferior‑lateral portion; contacts the diaphragm. |
Palpated at the apical impulse (PMI). |
| Base |
Broad superior surface; contains the atrial openings and the origins of the great vessels. |
Site of the aortic and pulmonic areas for auscultation. |
| Sutures (Grooves) |
Coronary sulcus (separates atria from ventricles) and interventricular sulci (anterior & posterior). |
Landmarks for coronary artery placement. |
| Surface Landmarks |
Aortic notch, pulmonary notch, left and right atrial appendages. |
Guide imaging and surgical approaches. |
3. Chambers & Their Walls
| Chamber |
Wall Thickness (approx.) |
Main Function |
| Right Atrium (RA) |
Thin |
Receives deoxygenated blood from systemic circulation (vena cavae). |
| Right Ventricle (RV) |
Moderately thick |
Pumps blood to pulmonary circulation via the pulmonary artery. |
| Left Atrium (LA) |
Thin |
Receives oxygen‑rich blood from pulmonary veins. |
| Left Ventricle (LV) |
Thickest (≈1 cm) |
Generates high pressure to deliver blood to systemic circulation via the aorta. |
- Septum: Muscular interventricular septum separates ventricles; membranous portion lies near the aortic valve.
4. Valves & Their Components
| Valve |
Location |
Leaflet Types |
Supporting Structures |
| Tricuspid |
RA ↔ RV (right AV valve) |
Anterior, posterior, septal leaflets |
Chordae tendineae → papillary muscles (RV). |
| Pulmonary |
RV → pulmonary artery |
Three semilunar cusps (anterior, left, right) |
Pulmonary trunk, annulus. |
| Mitral (Bicuspid) |
LA ↔ LV (left AV valve) |
Anterior & posterior leaflets |
Chordae → papillary muscles (anterolateral & posteromedial). |
| Aortic |
LV → aorta |
Three semilunar cusps (right, left, posterior) |
Aortic root, sinuses of Valsalva. |
- Function: Ensure unidirectional flow; prevent backflow during systole/diastole.
5. Coronary Circulation
| Vessel |
Origin |
Main Territory Supplied |
| Right Coronary Artery (RCA) |
Right aortic sinus |
Right atrium |