Overview
This lecture covers the anatomy of the heart, including blood circulation, external and internal structures, and the features of each heart chamber.
Blood Circulation Pathways
- The heart is located in the mediastinum between the lungs.
- Deoxygenated blood returns from the body to the right atrium via the superior and inferior vena cava.
- Blood moves from the right atrium through the tricuspid valve to the right ventricle.
- The right ventricle pumps deoxygenated blood through the pulmonary valve into the pulmonary artery and then to the lungs.
- Oxygenated blood returns from the lungs via pulmonary veins to the left atrium.
- Blood moves from the left atrium through the bicuspid (mitral) valve to the left ventricle.
- The left ventricle pumps blood through the aortic valve into the aorta for systemic circulation.
- Pulmonary circulation moves blood between the heart and lungs; systemic circulation moves blood between the heart and body.
External Heart Structures
- The apex is the pointy end, directed forward and left; the base is posterior and connected to great vessels.
- The heart has three main surfaces: pulmonary, sternocostal, and diaphragmatic.
- The right margin separates the sternocostal and diaphragmatic surfaces.
- The coronary sulcus separates atria from ventricles.
- The anterior and posterior interventricular sulci separate the right and left ventricles externally.
- The septum divides the heart into right (deoxygenated) and left (oxygenated) sides.
- The interventricular septum divides ventricles; the interatrial septum divides atria.
Right Atrium Features
- Six walls include anterior (with right auricle and pectinate muscle), posterior (openings for vena cava, sinus venarum), medial (interatrial septum with oval fossa), superior (superior vena cava opening), lateral (pectinate muscle), and inferior (tricuspid valve).
- The tricuspid valve has three cusps: anterior, posterior, and septal, and guards the opening to the right ventricle.
Right Ventricle Features
- Triangular shape; contains trabeculae carneae (ridges) to prevent blood swirling.
- Papillary muscles connect via tendinous chords to the tricuspid valve.
- Pulmonary valve has three semilunar cusps and leads to the pulmonary artery.
Left Atrium Features
- Anterior wall is the left auricle; posterior wall has four openings for pulmonary veins.
- The medial wall is the interatrial septum; the opening to the left ventricle is guarded by the mitral valve (bicuspid).
Left Ventricle Features
- Has structures similar to the right ventricle, including trabeculae carneae and papillary muscles.
- The mitral valve has two main cusps (anterior and posterior) and commissural cusps.
- The aortic valve consists of three semilunar cusps (right, posterior, left) and aortic sinuses.
Key Terms & Definitions
- Mediastinum — central area in the thorax where the heart is located.
- Apex of the heart — the pointed lower tip of the heart.
- Base of the heart — the upper, posterior part of the heart.
- Coronary Sulcus — groove separating atria from ventricles.
- Interventricular Septum — wall between the right and left ventricles.
- Interatrial Septum — wall between the right and left atria.
- Tricuspid Valve — right atrioventricular valve with three cusps.
- Mitral (Bicuspid) Valve — left atrioventricular valve with two main cusps.
- Trabeculae Carneae — muscular ridges inside the ventricles.
- Papillary Muscles — muscles attached to valve cusps via tendinous chords.
- Semilunar Valves — valves with three half-moon shaped cusps (pulmonary and aortic valves).
- Sinus Venarum — smooth part of the right atrium's posterior wall.
- Oval Fossa (Fossa Ovalis) — depression in the interatrial septum, remnant of fetal circulation.
Action Items / Next Steps
- Review the layers of the heart wall, conducting system, and heart topography in the next video.