Heart Anatomy

Heart Anatomy

Overview

• Anterior Surface: Front of the heart.

• Posterior Surface: Back of the heart.

• Inferior Surface: Apex (bottom) of the heart.

• Superior Surface: Base (pointing towards the right shoulder).

Anterior Structures

• Auricles: Fatty pouches on the atria.

• Pulmonary Trunk:

  • Takes deoxygenated blood from the right ventricle to the lungs for oxygenation.

  • Appears blue in models as it carries deoxygenated blood.

• Pulmonary Arteries: Left & Right Pulmonary Artery

• Aorta: The Largest Artery coming out of the heart / LV

  • Aortic Root: Normal Size 2-4 cm/ Connects to the aorta and contains the aortic valve, which opens to allow blood flow from the left ventricle into the aorta.

  • Ascending Aorta: The Initial part of the aorta.

  • Aortic Arch: The curved part of the aorta.

  • Descending Aorta: Thoracic Aorta & Abdominal Aorta

  • Branches off the Aortic Arch (in order):

    • Brachiocephalic Artery: Splits into the right subclavian and right common carotid arteries.

    • Left Common Carotid Artery

    • Left Subclavian Artery

Right Side Structures

• Right Atrium:

  • Superior Vena Cava: Dumps blood into the right atrium / receives deoxygenated blood from the upper body, including the head, neck, and arms

  • 3 Suppliers of Blood to SVC @ Right Atrium:

    • Brachiocephalic

    • Azygos

    • Coronary Sinus

  • Azygos Vein: Small veins feeding into the superior vena cava from the posterior side.

• Pulmonary Arteries:

  • Right Pulmonary Artery: Takes deoxygenated blood to the right lung.

  • Left Pulmonary Artery: Takes deoxygenated blood to the left lung.

• Pulmonary Veins:

  • Carry oxygenated blood back from the lungs to the heart (left atrium).

  • Left Pulmonary Veins

  • Right Pulmonary Veins

Coronary Bloodflow

• Coronary Arteries:

  • First branch off the ascending aorta.

  • Right Coronary Artery

  • Left Coronary Artery = Left Main

Anterior Aspect

• Left Coronary Artery Branches:

  • Anterior Interventricular Artery:

    • Also known as the left anterior descending (LAD) artery.

    • Supplies the anterior walls of both ventricles and the anterior interventricular septum.

    • Diagonal Arteries Branch off (D1 & D2)

  • Circumflex Artery:

    • Supplies the Lateral wall of the heart with blood

    • Obtuse Marginals Branch off (OM 1 & OM2)

• Veins:

  • Great Cardiac Vein:

    • Runs alongside the anterior interventricular artery.

    • Drains blood from the area supplied by the LAD.

  • Coronary Sinus: Collects deoxygenated venous blood from the heart muscle and drains into the right atrium.

Internal Heart Structures

Atria and Ventricles

• Right Atrium

• Left Atrium

• Right Ventricle

• Left Ventricle

Valves → Semilunar & Atrioventricular Valves

• ALL valves are held in place by the Chordae tendinae, and are anchored to Myocardium with Papillary Muscles

• Tricuspid Valve:

  • Separates the right atrium from the right ventricle.

  • Has chordae tendineae (collagen cords) attached to papillary muscles.

• Pulmonary Semilunar Valve:

  • Prevents backflow from the pulmonary trunk into the right ventricle.

• Mitral Valve (Bicuspid Valve):

  • Separates the left atrium from the left ventricle.

  • Has chordae tendineae attached to papillary muscles.

• Aortic Semilunar Valve:

  • Prevents backflow from the aorta into the left ventricle.

Other Internal Structures

• Fossa Ovalis:

  • Scar tissue in the right atrium.

  • Remnant of the foramen ovale in fetal circulation, which shunted blood from the right atrium to the left atrium to bypass the pulmonary circuit.

• Opening of the Coronary Sinus: Drains deoxygenated blood from the heart into the right atrium.

• Ligamentum Arteriosum:

  • Remnant of the ductus arteriosus in fetal circulation, which shunted blood from the pulmonary trunk to the aorta.

• Interventricular Septum:

  • Separates the two ventricles.

  • Defects can occur here (e.g., tetralogy of Fallot).

• Myocardium:

  • Muscular layer of the heart.

  • Made up of cardiac muscle fibers

• Endocardium:

  • Lines the internal chambers of the heart and valves.

  • Consists of simple squamous epithelial tissue (areolar connective tissue).

• Pectinate Muscles:

  • Muscle ridges in the anterior wall of the right and left atria.

• Trabeculae Carneae Muscles:

  • Irregular muscle fibers in the anterior walls of the ventricles.

• Epicardium:

  • Outer layer of the heart.