Anatomy of the Heart
Right Atrium
systemic blood enters through superior and inferior vena cavae, blood from heart through coronary sinus
pectinate muscles give the anterior atrial wall a rough, comb-like appearance
a vertical band, the crista terminalis, separates the smooth posterior from the anterior wall
the fossa ovalis is located on the posterior wall, and is the site of the fetal foramen ovale (lung bypass)
right auricle is a small pouch-like structure in the superior right quadrant of the anterior wall
conducting system (cannot be seen with unaided eye):
- sinoatrial node (SA node, pacemaker)— near orifice of superior vena cava, close to crista terminalis
- atrioventricular (AV) node—interatrial septum near the opening of the coronary sinus
Right Ventricle
tricuspid (right atrioventricular) valve—separate atrium/ventricle; 3 cusps (anterior, posterior, and septal)
chordae tendinae are narrow strands that connect tricuspid cusps to respective papillary muscles
trabeculae carnae are ridges in the ventricular wall
- one of them, the moderator band, is near the interventricular septa (part of conducting system; visible)
conus arteriosus is the narrow, superior part of the right ventricle through which blood passes
- at apex of conus, pulmonary semilunar valve (3 cusps - anterior, right, and left) to pulmonary trunk
Left Atrium
four pulmonary veins enter (a superior and inferior vein on each side)
unlike the right atrium, the interior walls are smooth except for the left auricle (pectinate muscles)
Left Ventricle
mitral (left atrioventricular) valve—2 cusps (anterior and posterior), chordae tendinae, papillary muscles, etc.
aortic semilunar valve (3 cusps - posterior, right, and left) leads to aorta
Coronary Arteries
first branches off aorta are right and left coronary arteries found in the aortic sinuses, superior to cusps
- right coronary artery
—in coronary sulcus (anterior surface, indicates location of atrioventricular septa)
- left coronary artery
—short distance posterior to the pulmonary trunk, divides into 2 branches
- left anterior descending artery (anterior interventricular) in the anterior interventricular sulcus
- circumflex artery in the coronary sulcus
coronary veins—parallel arterial distribution, into coronary sinus (in the coronary sulcus) then right atrium
Great Vessels
arteries out of aorta include brachiocephalic, subclavian, common carotid arteries
veins into vena cava include brachiocephalic vein
pulmonary arteries and veins (ligamentum arteriosum = remnant of fetal ductus arteriosus)
Pericardium
outer covering: course fibrous pericardium
anchors the heart to central tendon of the diaphragm, posterior surface of sternum and pleura
inner covering: serous pericardium (thinner) made of mesothelium and connective tissues—2 layers:
- parietal serous pericardium
—firmly adherent to the fibrous pericardium (outer layer)
- visceral serous pericardium
—epicardium directly applied to the surface of the heart muscle
- between these pericardia is a potential space, called the pericardial sac