Welcome to I HEART ANATOMY, an interactive educational resource for vasculature of the human heart. 

Please scroll down for information, pictures and interactive 3D models of the heart and accompanying cardiac vasculature. This page includes three sections:

 

1. Anatomy of the Heart

2. Vasculature of the Heart

3. Revision Materials

 

Anatomy of the Heart

 

 

The human heart is a muscular organ which pumps blood through the blood vessels of the circulatory system. Blood provides the body with oxygen and nutrients, as well as assists in the removal of metabolic wastes. The heart is located between the lungs, in the middle compartment of the chest. The heart consists of four chambers: two upper left and right atria and two lower left and right ventricles.

Functionally, the heart consists of two pumps. The right pump receives deoxygenated blood from the body and sends it to the lungs. The left pump receives oxygenated blood from the lungs and sends it to the body. Each pump consists of an atrium and ventricle separated by a valve, which prevents backflow. The heart pumps blood with a rhythm determined by a group of pacemaking cells in the sinoatrial node. These generate a current that causes contraction of the heart, traveling through the atrioventricular node and along the conduction system of the heart. The heart beats at an average resting rate between 60-100 beats per minute.

The heart is located in the middle mediastinum, at the level of thoracic vertebrae T5-T8. A fibroserous sac called the pericardium surrounds the heart and attaches to the mediastinum. The back surface (base) of the heart lies near the vertebral column, whereas the front (anterior) surface sits behind the sternum and rib cartilages. The upper part of the heart is the attachment point for several large blood vessels – the superior vena cava, aorta and pulmonary trunk.

The typical adult male heart is the size of a fist: 12 cm (5 in) in length, 8 cm (3.5 in) wide, and 6 cm (2.5 in) in thickness.

The 3D interactive heart model above includes annotations that reflect the general anatomy of the heart, with information on each. Please also see below for annotated pictures showing general anatomy of the heart in four different views (not including coronary vasculature annotations). To see larger views of these images, pause at the desired image, right-click the image and select ‘open image in new tab’.

 

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Vasculature of the Heart

Heart tissue, like all other tissues in the body, needs to be supplied with oxygen, nutrients and a way of removing metabolic wastes. This is achieved by the coronary vasculature, which includes coronary arteries and cardiac veins. Blood flow through these vessels relates to the heart muscle’s relaxation or contraction.

Coronary Arteries

 

Heart tissue receives blood from two coronary arteries which arise just above the aortic valve: the left coronary artery and right coronary artery.

Left coronary artery

The left coronary artery originates from the left aortic sinus of the ascending aorta. It passes between the pulmonary trunk and left auricle and then enters the coronary sulcus. Whilst still posterior to the pulmonary trunk, the artery divides into its two terminal branches:

  • Anterior interventricular branch: continues around the left side of the pulmonary trunk and descends towards the apex of the heart by travelling along the anterior interventricular groove (sulcus) in the heart muscle. During its course, a couple of large diagonal branches may arise and descend diagonally across the anterior surface of the left ventricle. Anastomosis with the posterior interventricular branch of the right coronary artery is common.
  • Circumflex branch: travels along the left atrioventricular groove( left coronary sulcus), which it follows to the base of the heart, and usually ends before reaching the posterior interventricular sulcus. The left marginal artery, a large branch, usually arises from the circumflex branch and continues across the left side of the heart. Along its course, the circumflex branch may also give rise to a posterior left ventricular branch and atrial branch.

The distribution pattern of the left coronary artery allows it to supply most of the left atrium, left ventricle and interventricular septum.

Right coronary artery

The right coronary artery originates from the right aortic sinus of the ascending aorta. It passes anteriorly and to the right between the right auricle and the pulmonary trunk. It then descends vertically in the right coronary sulcus, between the right atrium and right ventricle, towards the base of the heart. Along its course, it gives rise to several branches:

  • Atrial branch: travels in the groove between the right auricle and ascending aorta, giving off the sinoatrial nodal branch which passes posteriorly around the superior vena cava to supply the sinoatrial node
  • Conus branch: arises from the proximal end of the right coronary artery
  • Ventricular branches: arise from the right coronary artery as it travels along the right coronary sulcus
  • Right marginal branch: given off as the right coronary artery approaches the inferior margin of the heart and travels along this margin towards the apex
  • Posterior interventricular branch: arises from the right coronary artery at the base of the heart and travels along the posterior interventricular groove towards the apex of the heart. Anastomosis with the anterior interventricular branch of the left coronary artery is common.
  • Right posterolateral branch: also travels along the base of the heart, on the diaphragmatic surface of the left ventricle

Through its distribution pattern, the right coronary artery supplies the right atrium, right ventricle, sinoatrial and atrioventricular nodes, the interatrial septum, a portion of the left atrium, the posteroinferior one-third of the atriventricular septum and part of the left ventricle.

NB. As with all blood vessels, there may be variations in the distribution of the coronary arteries. However, the distribution pattern described above and seen in the images is the most common.

 

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Cardiac Veins

 

The returning venous blood from the heart tissues passes through the cardiac veins, most of which empty into the coronary sinus, a large venous structure located in the conorary sulcus on the posterior surface of the heart (between the left atrium and left ventricle). The coronary sinus then drains into the right atrium, near the opening of the inferior vena cava.

The coronary sinus receives blood from four major tributaries: the great cardiac vein, middle cardiac vein, small cardiac vein and posterior cardiac vein.

Great cardiac vein

The great cardiac vein begins at the apex of the heart. It ascends in the anterior interventricular sulcus, where it often accompanies the interventricular artery and therefore often termed the anterior interventricular vein. Upon reaching the coronary sulcus, the great cardiac vein turns to the left and continues over the base surface of the heart, where it is related to the circumflex branch of the left coronary artery.  Whilst the great cardiac vein gradually enlarges to form the coronary sinus, it receives blood from the left marginal vein, which ascends along the left margin of the heart, and small tributaries of the coronary sinus.

Middle cardiac vein

The middle cardiac vein begins near the apex of the heart and ascends in the posterior interventricular groove toward the coronary sinus. It is associated with the posterior interventricular branch of the right coronary artery throughout its course.

Small cardiac vein

The small cardiac vein often accompanies the right coronary artery and its right marginal branch. It travels through the coronary sulcus between the right atrium and right ventricle before entering the coronary sinus at its atrial end.

Posterior cardiac vein

The posterior cardiac vein travels along the posterior surface of the left ventricle, just to the left of the middle cardiac vein, and empties into the coronary sinus.

Other cardiac veins

The right marginal vein assists in the draining of the right atrium and right ventricle and enters the atrium directly (although sometimes it drains into the small cardiac vein)

The anterior veins of the right ventricle (anterior cardiac veins) are small veins that arise on the anterior surface of the right ventricle. They accompany the ventricular branches of the right coronary artery and drain into the right atrium.

The left marginal vein drains the lateral left ventricular wall and empties into the coronary sinus.

The small tributaries of the coronary sinus assist in the drainage of the posterior left ventricular wall.

 

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Revision Materials

 

Please see the slideshow below for revision materials on the anatomy of the heart, coronary arteries and cardiac veins. These are essentially unlabelled versions of the images seen on this webpage that may help aid revision. To see larger views of these images, pause at the desired image, right-click the image and select ‘open image in new tab’. These can then be saved onto your desktop and printed if desired.

 

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Written, illustrated and sculpted by Hannah Newey

©Hannah Newey 2018

 

References:

Drake, R., Vogl, A. and Mitchell, A. ed., (2010). Thorax. In: Gray’s Anatomy for Students, 2nd ed. Philadelphia: Churchill Livingstone Elsevier, pp.180-210.

Complete Anatomy. (2018). 3D4Medical (Version 3.3.0 (5574)) [iPad application software]. Retrieved from https://itunes.apple.com/gb/store

 

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