Cardiovascular System Anatomy

Study Notes

The heart is a four-chambered muscular pump located in the middle mediastinum.
The heart is positioned obliquely, with two-thirds lying on the left side and one-third on the right.
The average heart size is comparable to a clenched fist, with an average weight of 280 grams.
The heart has upper atrial/venous chambers and lower ventricular/arterial chambers.
The atria and ventricles are separated externally by the coronary sulcus.

Sterno-costal/anterior surface: Directed forward and upward, formed by the anterior surface of the right atrium and auricle, part of the left auricle, anterior surface of the right ventricle (two-thirds), and anterior surface of the left ventricle (one-third).
Diaphragmatic/inferior surface: Flat, facing upward and backward, formed entirely by the two ventricles (two-thirds by the left ventricle, one-third by the right ventricle). It lies over the central tendon of the diaphragm.

Right border: Formed by the right atrium, rounded and convex. Extends from the superior vena cava (SVC) to the inferior vena cava (IVC). Contains a shallow vertical groove between SVC and IVC. Separates base from the sterno-costal surface.
Inferior border: Sharp, extending from the IVC to the apex of the heart. Contains a notch called the incisura apicis cordis, close to the apex.
Left border: Ill-defined, extends from the left auricle to the apex of the heart. Separates the sterno-costal surface from the left surface.

The heart's external surface is demarcated by grooves.
Atrioventricular groove: Surrounds the heart, but deficient in front due to the pulmonary trunk. Consists of anterior and posterior parts. Anteriorly, it features the right coronary artery, left circumflex branch of the left coronary artery, termination of the great cardiac vein, and commencement of the coronary sinus.
Posterior part of the atrioventricular groove: Located between the base and diaphragmatic surface. Contains the coronary sinus and anastomosis of the right and left coronary arteries.
Anterior interventricular groove: Runs downward, forward, and parallel to the left border. Meets the inferior border at the incisura apicis cordis. Indicates anterior attachment of interventricular septum. Contains the anterior interventricular artery, a branch of the left coronary artery and great cardiac vein.
Posterior interventricular groove: Runs forward along the posterior surface. Meets the incisura apicis cordis. Indicates posterior attachment of interventricular septum. Contains posterior interventricular branch of the right coronary artery and middle cardiac vein.

The heart wall consists of three layers: epicardium (visceral pericardium), myocardium, and endocardium.

Has a muscular extension called the auricle.
Its anterior wall has thin muscular ridges called pectinate muscles.
Receives blood from three large veins: superior vena cava, inferior vena cava, and coronary sinus.

Has a thicker wall than the atria.
The muscle projects into the cavity as papillary muscles ending in chordae tendineae.
Receives deoxygenated blood from the right atrium through the atrioventricular orifice (guarded by the tricuspid valve).
Ejects blood to the lungs via the pulmonary trunk through the semilunar pulmonary valve.

Has a muscular extension called the auricle.
Receives oxygenated blood from the lungs via four pulmonary veins.
Pumps blood into the left ventricle via the left atrioventricular orifice (guarded by the bicuspid or mitral valve).

Forms the apex of the heart with a wall noticeably thicker than the right ventricle.
The muscle projects into the cavity as papillary muscles.
Receives oxygenated blood from the left atrium via the bicuspid valve.
Ejects blood into the aorta via the semilunar aortic valve.

The heart is supplied by the right and left coronary arteries.
These arteries arise from the left and right aortic sinuses.
The right coronary artery (RCA) branches to the right marginal artery (RMA) and the posterior interventricular artery (Plv).
The left coronary artery (LCA) branches into the left anterior descending artery (LAD), the left marginal artery (LMA), and the circumflex artery (Cx).

Collect waste products from the myocardium.
Drain into the coronary sinus, which empties into the right atrium.
Major veins include the great cardiac vein, middle cardiac vein, small cardiac vein, and anterior cardiac vein.