Cardiac anatomy

The sinoatrial node (often abbreviated SA node; also commonly called the sinus node and less commonly the sinuatrial node) is the normal natural pacemaker of the heart and is responsible for the initiation of the cardiac cycle (heartbeat).

The atrium (plural: atria) is one of the two blood collection chambers of the heart.

Cardiac muscle cells or cardiomyocytes (also known as myocardiocytes or cardiac myocytes) are the muscle cells (myocytes) that make up the cardiac muscle.

In the heart, a ventricle is one of two large chambers that collect and expel blood received from an atrium towards the peripheral beds within the body and lungs.

The mitral valve, also known as the bicuspid valve or left atrioventricular valve, is a dual-flap valve in the heart that lies between the left atrium and the left ventricle.

The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, between the right atrium and the right ventricle.

The aortic valve is a valve in the human heart between the left ventricle and the aorta.

The pulmonary valve (sometimes referred to as the pulmonic valve) is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps.

Cardiac muscle (heart muscle) is an involuntary, striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium.

Coronary circulation is the circulation of blood in the blood vessels of the heart muscle myocardium known as coronary arteries.

A heart valve normally allows blood to flow in only one direction through the heart.

The pericardium (from the Greek περί, "around" and κάρδιον, "heart") is a double-walled sac containing the heart and the roots of the great vessels.

The endocardium is the innermost layer of tissue that lines the chambers of the heart.

The infundibulum (also known as conus arteriosus) is a conical pouch formed from the upper and left angle of the right ventricle in the chordate heart, from which the pulmonary trunk arises.

The atrioventricular (AV) node is a part of the electrical conduction system of the heart that coordinates the top of the heart.

The pectinate muscles (musculi pectinati) are parallel ridges in the walls of the atria of the heart.

The interventricular septum (IVS), (or ventricular septum, or during development septum inferius), is the stout wall separating the lower chambers (the ventricles) of the heart from one another.

The right atrioventricular orifice (right atrioventricular opening) is the large oval aperture of communication between the right atrium and ventricle.

The valve of the coronary sinus (Thebesian Ring) is a semicircular fold of the lining membrane of the right atrium, at the orifice of the coronary sinus.

The valve of the inferior vena cava (eustachian valve) is a venous valve that lies at the junction of the inferior vena cava and right atrium.

There are two pericardial sinuses: transverse and oblique.

The bundle branches, or Tawara branches, are offshoots of the bundle of His in the heart's ventricle.

The Purkinje fibers (/pərˈkɪndʒiː/ pər-KIN-jee) (Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium.

The atria of the heart are separated from the ventricles by the coronary sulcus (also called coronary groove, auriculoventricular groove, atrioventricular groove, AV groove); this contains the trunks of the nutrient vessels of the heart, and is deficient in front, where it is crossed by the root of the pulmonary trunk.

The fold of the left vena cava, ligament of the left vena cava, or vestigial fold of Marshall, is a triangular fold of the serous pericardium that lies between the left pulmonary artery and subjacent pulmonary vein.

The interatrial sulcus, separating the two atria, is scarcely marked on the posterior surface, while anteriorly it is hidden by the pulmonary artery and aorta.

The terminal sulcus is a groove in the right atrium of the heart.

The bundle of His or His bundle is a collection of heart muscle cells specialized for electrical conduction.

The cardiac skeleton, also known as the fibrous skeleton of the heart, is a high density single structure of connective tissue that forms and anchors the valves and influences the forces exerted through them.

The chordae tendinae (tendinous chords), or heart strings, are cord-like tendons that connect the papillary muscles to the tricuspid valve and the mitral valve in the heart.

In the heart's conduction system, Bachmann's bundle (also called the Bachmann bundle or the interatrial tract) is a branch of the anterior internodal tract that resides on the inner wall of the left atrium.

The aorticopulmonary septum (also called the spiral septum, or aortic septum in older texts) is developmentally formed from neural crest, specifically the cardiacneural crest, and actively separates the aorta and pulmonary arteries and fuses with the interventricular septum within the heart during heart development.

The anterior longitudinal sulcus and posterior longitudinal sulcus extend from the base of the ventricular portion to a notch, the incisura apicis cordis (or notch of cardiac apex), on the acute margin of the heart just to the right of the apex.

The left margin of heart (or obtuse margin) is shorter than the right border of heart, full, and rounded: it is formed mainly by the left ventricle, but to a slight extent, above, by the left atrium.

The anterior interventricular sulcus (or anterior longitudinal sulcus) is one of two grooves that separates the ventricles of the heart, the other being the posterior interventricular sulcus.

The intervenous tubercle (tubercle of Lower) is a small projection on the posterior wall of the right atrium, above the fossa ovalis.

The opening of the pulmonary artery (or trunk) is circular in form, and situated at the summit of the conus arteriosus, close to the ventricular septum.

The posterior interventricular sulcus or posterior longitudinal sulcus is one of the two grooves that separates the ventricles of the heart and is on the diaphragmatic surface of the heart near the right margin.

The right margin of the heart (right border of heart) is long, and is formed by the right atrium above and the right ventricle below.

The fibrous pericardium is attached to the posterior surface of the sternum by the superior and inferior sternopericardiac ligaments (sternopericardial ligaments); the upper passing to the manubrium, and the lower to the xiphoid process.

The left atrioventricular orifice (left atrioventricular opening or mitral orifice) is placed below and to the left of the aortic orifice.

The smallest cardiac veins (or Thebesian veins) are minute valveless veins in the walls of all four heart chambers.

Intercalated discs are microscopic identifying features of cardiac muscle.

The aortic sac or aortic bulb is a dilated structure in mammalian embryos, lined by endothelial cells located just above (superior to) the truncus arteriosus.

The atrioventricular septum is a septum of the heart between the right atrium (RA) and the left ventricle (LV).

The papillary muscles are muscles located in the ventricles of the heart.