Region: Mediastinum

Left Coronary Artery

Left Coronary Artery The structure indicated is the left coronary artery. The left coronary artery (LCA) arises from the left aortic sinus of the ascending aorta. The left coronary artery has two terminal branches: Left anterior descending (LAD)/anterior interventricular Circumflex branch The left circumflex artery (LCX) supplies blood to the posterolateral left ventricle as well as the anterolateral papillary muscle and provides part of the supply to the left ventricle. The left anterior descending artery also supplies the left ventricle, and is responsible for the arterial supply to the anterolateral myocardium, the apex of the heart and the interventricular septum. …

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left coronary artery

Small Cardiac Vein

Small Cardiac Vein The structure indicated is the small cardiac vein. The coronary sinus lies posteriorly on the heart in the coronary sulcus and receives four cardiac veins: Great cardiac vein Middle cardiac vein Small cardiac vein Posterior cardiac veins The coronary sinus returns deoxygenated blood to the right atrium of the heart, together with the superior and inferior vena cavae. The small cardiac vein lies in the coronary sulcus between the right atrium and the right ventricle. Learn more about the blood supply to the heart in this tutorial.

Left Bundle Branch

Left Bundle Branch The structure indicated is the left bundle branch of the cardiac conducting system. The conduction system of the heart is responsible for the synchronised contraction of the atria and ventricles and is comprised of the following main structures: Sinoatrial node Atrioventricular node Atrioventricular bundle of His Right and left bundle branches Purkinje fibres The electrical activity of the heart begins in the sinoatrial node and travels to the atrioventricular node. From the atrioventricular node the impulses pass down the Bundle of His, whereupon the conducting fibres divide into the right and left bundle branches. The right bundle …

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left bundle branch

Pulmonary Trunk

Pulmonary Trunk The structure indicated is the pulmonary trunk. The pulmonary trunk is one of the great vessels – a term which refers to the major arteries and veins which bring blood to and from the heart. These include: Superior and inferior vena cavae Pulmonary arteries Pulmonary veins Aorta The pulmonary trunk carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation, via the right and left pulmonary arteries. This is the only artery in the adult human body that carries deoxygenated blood. In fetal life, the umbilical arteries also carry deoxygenated blood – this …

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pulmonary trunk

Purkinje Fibres

Purkinje Fibres The diagram indicates purkinje fibres. The conduction system of the heart is responsible for the synchronised contraction of the atria and ventricles and is comprised of the following main structures: Sinoatrial node Atrioventricular node Atrioventricular bundle of His Right and left bundle branches Purkinje fibres The atrioventricular nodes receives signals from the sinoatrial node. The impulses from the atrioventricular node then pass to the Bundle of His and then follow the left and right bundle branches through the interventricular septum and ultimately to the Purkinje fibres which propagate the signal into the ventricles. Purkinje fibres are located on …

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purkinje fibres

Right Coronary Artery

Right Coronary Artery The structure indicated is the right coronary artery of the heart. The coronary arteries arise from the aortic sinuses of the ascending aorta. The right coronary artery (RCA) arises from the right aortic sinus and the left coronary from the left aortic sinus. The right coronary artery then runs in the coronary sulcus, which separates the atria from the ventricles. The right coronary artery gives off the following branches: Atrial arteries Right marginal branch Posterior interventricular branch (posterior descending artery) The coronary artery from which the posterior descending artery arises determines the coronary dominance. The posterior descending artery …

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right coronary artery

Atrial Arteries

Atrial Arteries The structures indicated are the atrial branches of the right coronary artery. The atrial arteries come off the right coronary artery to supply the right atrium of the heart. The atrial arteries are often describes in terms of three groups: Anterior Lateral Posterior The anterior and lateral branches mainly supply the right atrium, whereas the posterior branch supplies both the right and left atria. Learn more about the blood supply to the heart in this anatomy tutorial.

atrial arteries

Atrioventricular Node

Atrioventricular Node The structure indicated is the atrioventricular node. The conduction system of the heart is responsible for the synchronised contraction of the atria and ventricles and is comprised of the following main structures: Sinoatrial node Atrioventricular node Atrioventricular bundle of His Right and left bundle branches Purkinje fibres The atrioventricular node is located centrally in the Triangle of Koch, between the atria and ventricles in the infero-posterior portion of the interatrial septum close to the opening of the coronary sinus. The triangle of Koch has the following boundaries: Ostium of coronary sinus Tendon of Todaro Anterior-septal leaflet commissure The …

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atrioventricular node

Sinoatrial Node

Sinoatrial Node The structure indicated is the sinoatrial node The conduction system of the heart is responsible for the coordinated contraction of the atria and ventricles and is comprised of the following main structures: Sinoatrial node Atrioventricular node Atrioventricular bundle of His Right and left bundle branches Purkinje fibres The sinoatrial node, often referred to as the SA node, is the pacemaker of the heart. It is located in the right atrium and is responsible for generating normal sinus rhythm. The sinoatrial node is located lateral to the junction where the superior vena cava enters the right atrium. Electrical signals generated …

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sinoatrial node

Aortic Arch

Aortic Arch The structure indicated is the arch of the aorta. The aorta arises from the left ventricle of the heart and supplies the body with oxygenated blood. The aorta can be divided into thoracic and abdominal parts (the thoracic aorta pierces the diaphragm to enter the abdominal cavity, becoming the abdominal aorta). The thoracic aorta consists of: Ascending aorta Aortic arch Descending (thoracic) aorta The aortic arch lies in the superior mediastinum and begins and ends at the level of the angle of Louis (sternal angle) which lies at the level of the intervertebral disc between T4/T5. The arch …

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aortic arch