Download Anatomy of the Heart

Anatomy of the Heart
The heart is the pump of the cardiovascular system. It is composed of four chambers.
Two chambers (the atria) are receiving chambers, and two (the ventricles) are pumping
chambers. The right heart is separated from the left heart by a wall or septum. The great
vessels of the heart are veins and arteries associated with the chambers. Veins carry
blood toward the heart and arteries carry blood away from the heart.
The human heart is about the size of a fist and is located in the space between the lungs
called the mediastinum. It extends from the second rib to the fifth intercostal space,
between the sternum and the vertebral column. It is oblique in the thorax and tipped to
the left. About 2/3 of the heart is to the left of the midsternal line.
The apex of the heart is the pointed end and is inferior to the base.
The heart is covered with two layers of serous membranes - the visceral and parietal
serous pericardia (s. pericardium). The visceral layer is thin and tightly adhered to the
heart. It is also called the epicardium. The parietal layer is surrounded by a tough fibrous
pericardium.
The space between the two layers of serous pericardium is called the pericardial space
and is filled with pericardial fluid secreted by the serous membranes.
The wall of the heart includes:
the outer epicardium (visceral layer of serous pericardium) pericardium
the myocardium - cardiac muscle; the layer that contracts
the endocardium - smooth heart lining of simple squamous epithelium continuous with
the lining of blood vessels called the endothelium
The fibrous "skeleton" of the heart is connective tissue that supports the heart valves
and separates the atria from the ventricles. It does not contain bone!
Chambers, Vessels and Valves of the Heart
The Right Heart
Right Atrium
 Receives blood from 3 major veins, the superior vena cava (blood from upper
body), the inferior vena cava (blood from lower body) and the coronary sinus
(blood from the heart muscle itself - coronary circulation)
 Thin walls - not a strong pump
 Auricle - provides extra volume
 Pectinate muscles - columnar muscles that offer support
 Fossa ovalis - depression in septum left when the foramen ovale between the right
and left atria closes after birth.
Tricuspid Valve
 Atrioventricular valve with three flaps separates the atrium and the ventricle
Right Ventricle
 Myocardium thicker than in atrium - pumps to pulmonary circuit
 Papillary muscles secure chordae tendineae of the tricuspid atrioventricular valve
(AV valve)

Blood exits through the pulmonary semilunar valve to the pulmonary trunk which
branches to form the right and left pulmonary arteries of the pulmonary circuit.
The Left Heart
Left Atrium
 Similar to the right atrium
 Receives blood from pulmonary veins
Bicuspid Valve
 Atrioventricular valve with two flaps separates the atrium and the ventricle
Left Ventricle
 Myocardium thicker than myocardium of right ventricle - pumps to systemic
circuit
 Papillary muscles secure chordae tendineae attached to flaps of the valve
 Blood exits through the aortic semilunar valve to the aorta to the systemic circuit.