The SA Node is a small cluster of specialized heart cells that normally starts each heartbeat. It sits in the right atrium, near where a large vein (the superior vena cava) enters the heart. It is commonly discussed when clinicians interpret an electrocardiogram (ECG) or evaluate heart rhythm symptoms. It is often called the heart’s “natural pacemaker,” meaning it sets the typical resting heart rate.
The Sinoatrial Node is a small cluster of specialized heart cells that normally starts each heartbeat. It sits in the right atrium, near where blood returns to the heart through the superior vena cava. It is commonly discussed when clinicians evaluate heart rhythm, pulse rate, and causes of palpitations or fainting.
The Cardiac Conduction System is the heart’s built-in electrical wiring that coordinates each heartbeat. It generates and carries signals that tell the heart muscle when to contract and relax. It is discussed every day in cardiology when interpreting an ECG (electrocardiogram) and evaluating rhythm symptoms. It is also central to understanding pacemakers, heart block, and many arrhythmias.
The Cardiac Skeleton is a firm framework of fibrous (collagen-rich) tissue inside the heart. It supports and shapes the heart valves and helps the heart keep its structure while beating. It also acts as electrical “insulation” between the upper and lower chambers. Clinicians commonly reference it in valve disease, conduction problems, and cardiac imaging or surgery planning.
Cardiac Base refers to the broad, upper part of the heart opposite the apex (the pointed tip). It is formed mainly by the atria and the attachments to the great vessels (such as the aorta and pulmonary artery). Clinicians use the term to describe anatomy during exams, imaging interpretation, and procedural planning. It is also a common reference point when discussing murmurs and disease involving the valves and aortic root.
The **Cardiac Apex** is the pointed, lower tip of the heart. It is formed mainly by the left ventricle and sits toward the left side of the chest. Clinicians use it as an anatomic landmark during physical exams and heart imaging. It is also referenced when describing certain heart diseases and procedure approaches.
The Interatrial Septum is the wall of tissue that separates the heart’s right atrium from the left atrium. It helps keep oxygen-poor and oxygen-rich blood on their correct pathways through the heart. Clinicians commonly refer to it during echocardiograms and other heart imaging tests. It is also an important landmark for catheter-based procedures that need access to the left atrium.
The Interventricular Septum is the wall of heart muscle that separates the right and left ventricles. It helps keep oxygen-poor and oxygen-rich blood from mixing inside the heart. Clinicians assess it on cardiac imaging and during physical evaluation of heart disease. It is also discussed in conditions such as heart muscle thickening, conduction problems, and congenital defects.
The Ventricular Septum is the thick wall of heart muscle that separates the right and left ventricles. It helps keep oxygen-poor blood (right side) and oxygen-rich blood (left side) from mixing. Clinicians reference it in heart imaging, heart murmur evaluation, and structural heart disease care. It is also central to certain heart rhythm pathways and some cardiac procedures.
Atrial Septum is the thin wall of tissue that separates the heart’s two upper chambers (the right atrium and left atrium). It helps keep oxygen-poor blood and oxygen-rich blood moving through the correct sides of the heart. Clinicians refer to the Atrial Septum in imaging, catheter-based procedures, and when evaluating “holes in the heart.” It is also a key landmark for accessing the left atrium during many modern electrophysiology and structural heart procedures.
The Right Ventricle is one of the four chambers of the heart. It receives blood from the body and pumps it to the lungs for oxygen. Clinicians use the term when describing heart function, heart failure, and lung–heart interactions. It is commonly assessed during echocardiograms, cardiac MRI, and catheter-based testing.
Left Ventricle is the heart’s main pumping chamber on the left side. It receives oxygen-rich blood from the left atrium and pumps it to the body through the aorta. Clinicians discuss the Left Ventricle when evaluating blood pressure, shortness of breath, chest pain, and heart failure. It is commonly assessed with imaging tests such as echocardiography (“echo”) and cardiac MRI.
The Right Atrium is one of the four chambers of the heart. It receives oxygen-poor blood returning from the body and directs it to the right ventricle. Clinicians discuss the Right Atrium when evaluating right-sided heart function, rhythm problems, and venous blood flow. It is also a key landmark in common heart imaging and catheter-based procedures.
The Left Atrium is one of the four chambers of the heart. It receives oxygen-rich blood from the lungs and passes it to the left ventricle. Clinicians refer to the Left Atrium in imaging reports, rhythm evaluations, and valve disease assessments. It is also discussed in conditions linked to atrial fibrillation and stroke risk.
Heart Chambers are the four hollow spaces inside the heart that collect and pump blood. They include two atria (upper chambers) and two ventricles (lower chambers). Clinicians refer to Heart Chambers when explaining blood flow, heart function, and many common cardiac tests.
The Pericardial Sac is the thin, protective covering that surrounds the heart. It helps the heart move smoothly as it beats and keeps it positioned in the chest. Clinicians refer to the Pericardial Sac during heart imaging, emergency evaluation, and cardiac surgery. Problems involving the Pericardial Sac can affect breathing, chest comfort, and blood flow.
The Pericardial Space is the thin, fluid-containing gap around the heart. It sits between two layers of the pericardium, the sac that encloses the heart. Clinicians reference it in imaging and bedside exams when evaluating fluid or inflammation. It is also the target space for certain procedures that drain fluid or allow catheter access.
Pericardium is the sac-like structure that surrounds the heart. It helps protect the heart and allows it to move smoothly as it beats. Clinicians commonly discuss the Pericardium in conditions like inflammation or fluid around the heart. It is also referenced in cardiac imaging and in some heart surgeries.
Epicardium is the thin outer layer of the heart wall. It is also called the visceral layer of the pericardium. Epicardium covers the heart’s surface and helps it move smoothly as it beats. Clinicians commonly reference Epicardium in imaging, heart surgery, and certain rhythm procedures.
Endocardium is the thin inner lining of the heart chambers and heart valves. It is the surface that directly touches circulating blood. Clinicians refer to Endocardium when discussing heart valve disease, clots, infection, and certain rhythm problems. It is commonly evaluated with cardiac imaging such as echocardiography.