Heart Anatomy and Location
📌 The heart is a muscular organ slightly larger than a clenched fist, located in the thorax within the mediastinum between the two lungs.
🛡️ It is covered by the pericardium, a tough membrane separating it from other mediastinal structures.
🔺 The heart is functionally divided into the right heart (right atrium and ventricle) and the left heart (left atrium and ventricle).

Blood Flow and Circulation
💨 Poorly oxygenated blood enters the right atrium via the superior and inferior vena cava, moves to the right ventricle, and is pumped to the lungs via the pulmonary trunk (pulmonary circulation).
⛽ Oxygenated blood returns from the lungs via four pulmonary veins to the left atrium, passes to the left ventricle, and is pumped into the aorta to the body (systemic circulation).
⬅️ The heart is rotated leftward; the apex points anteriorly and slightly to the left, formed by the tip of the left ventricle.

Heart Chambers and Borders (External View)
⬆️ The superior border is formed by the right and left Atria, including the superior vena cava, ascending aorta, aortic arch, and pulmonary trunk.
⬇️ The inferior border is mostly the right ventricle and part of the left ventricle.
⬅️ The left border is mainly the left ventricle and part of the left auricle.

Internal Structures of the Right Heart
🚪 The right atrium has a smooth posterior part (sinus venarum) and a rough anterior part with pectinate muscles, separated by the sulcus terminalis externally and the crista terminalis internally.
♦️ Blood enters the right ventricle through the tricuspid orifice, guarded by the tricuspid valve (three cusps: anterior, posterior, septal) attached to papillary muscles via chordae tendineae.
🔗 The moderator band (septomarginal trabecula) crosses the right ventricle, ensuring coordinated contraction by linking the interventricular septum to the anterior papillary muscle.

Internal Structures of the Left Heart
💪 The left ventricle walls are two to three times thicker than the right ventricle due to higher pressure demands for systemic circulation.
Ⓜ️ The left AV orifice is guarded by the mitral valve (bicuspid valve, two cusps: anterior and posterior).
🚪 The left ventricle forms the apex of the heart.

Valves and Coronary Artery Supply
💨 Semilunar valves (Pulmonary and Aortic) have three cusps and close passively during ventricular relaxation due to reverse blood flow, preventing backflow.
❤️ The sinuses above the aortic valve cusps fill during relaxation, serving as the origin points for the right and left coronary arteries, which nourish the heart muscle.

Cardiac Conduction System and Innervation
💓 The sinoatrial (SA) node, located near the junction of the superior vena cava and right atrium, is the pacemaker, setting the basic heart rhythm.
⚡ The impulse spreads from the SA node to the AV node, then via the AV bundle and Purkinje fibers to stimulate coordinated ventricular contraction.
🌿 The heart is supplied by the cardiac plexus, containing sympathetic fibers (increase heart rate/force) and parasympathetic fibers (slow heart rate) from the vagus nerves.

Key Points & Insights
➡️ The heart is physically structured with the left ventricle wall being significantly thicker (2-3 times) than the right to handle the high pressure of systemic circulation.
➡️ The SA node acts as the heart's pacemaker, initiating the impulse near the junction of the superior vena cava and right atrium.
➡️ Coronary arteries fill during ventricular relaxation when the backflow of blood fills the sinuses above the aortic valve cusps.
➡️ The tricuspid valve has three cusps, while the mitral valve has two cusps, both anchored by chordae tendineae to papillary muscles to prevent backflow during systole.

📸 Video summarized with SummaryTube.com on Oct 05, 2025, 06:44 UTC

Heart Anatomy and Location
📌 The heart is a muscular organ slightly larger than a clenched fist, located in the thorax within the mediastinum between the two lungs.
🛡️ It is covered by the pericardium, a tough membrane separating it from other mediastinal structures.
🔺 The heart is functionally divided into the right heart (right atrium and ventricle) and the left heart (left atrium and ventricle).

Blood Flow and Circulation
💨 Poorly oxygenated blood enters the right atrium via the superior and inferior vena cava, moves to the right ventricle, and is pumped to the lungs via the pulmonary trunk (pulmonary circulation).
⛽ Oxygenated blood returns from the lungs via four pulmonary veins to the left atrium, passes to the left ventricle, and is pumped into the aorta to the body (systemic circulation).
⬅️ The heart is rotated leftward; the apex points anteriorly and slightly to the left, formed by the tip of the left ventricle.

Heart Chambers and Borders (External View)
⬆️ The superior border is formed by the right and left Atria, including the superior vena cava, ascending aorta, aortic arch, and pulmonary trunk.
⬇️ The inferior border is mostly the right ventricle and part of the left ventricle.
⬅️ The left border is mainly the left ventricle and part of the left auricle.

Internal Structures of the Right Heart
🚪 The right atrium has a smooth posterior part (sinus venarum) and a rough anterior part with pectinate muscles, separated by the sulcus terminalis externally and the crista terminalis internally.
♦️ Blood enters the right ventricle through the tricuspid orifice, guarded by the tricuspid valve (three cusps: anterior, posterior, septal) attached to papillary muscles via chordae tendineae.
🔗 The moderator band (septomarginal trabecula) crosses the right ventricle, ensuring coordinated contraction by linking the interventricular septum to the anterior papillary muscle.

Internal Structures of the Left Heart
💪 The left ventricle walls are two to three times thicker than the right ventricle due to higher pressure demands for systemic circulation.
Ⓜ️ The left AV orifice is guarded by the mitral valve (bicuspid valve, two cusps: anterior and posterior).
🚪 The left ventricle forms the apex of the heart.

Valves and Coronary Artery Supply
💨 Semilunar valves (Pulmonary and Aortic) have three cusps and close passively during ventricular relaxation due to reverse blood flow, preventing backflow.
❤️ The sinuses above the aortic valve cusps fill during relaxation, serving as the origin points for the right and left coronary arteries, which nourish the heart muscle.

Cardiac Conduction System and Innervation
💓 The sinoatrial (SA) node, located near the junction of the superior vena cava and right atrium, is the pacemaker, setting the basic heart rhythm.
⚡ The impulse spreads from the SA node to the AV node, then via the AV bundle and Purkinje fibers to stimulate coordinated ventricular contraction.
🌿 The heart is supplied by the cardiac plexus, containing sympathetic fibers (increase heart rate/force) and parasympathetic fibers (slow heart rate) from the vagus nerves.

Key Points & Insights
➡️ The heart is physically structured with the left ventricle wall being significantly thicker (2-3 times) than the right to handle the high pressure of systemic circulation.
➡️ The SA node acts as the heart's pacemaker, initiating the impulse near the junction of the superior vena cava and right atrium.
➡️ Coronary arteries fill during ventricular relaxation when the backflow of blood fills the sinuses above the aortic valve cusps.
➡️ The tricuspid valve has three cusps, while the mitral valve has two cusps, both anchored by chordae tendineae to papillary muscles to prevent backflow during systole.

📸 Video summarized with SummaryTube.com on Oct 05, 2025, 06:44 UTC