anatomy

• Heart


  A muscular organ that pumps blood around the body by circulating it through the circulatory/vascular system
• Pericardium


  A two-layered serous sac that wraps around the heart

  
• Heart


  • Pyramid shaped
  • Lies within the pericardium in the middle mediastinum
  • Connected at its base to the great blood vessels
  • Base faces the posterior thoracic wall
  • Apex is pointed toward the anterior thoracic wall
  • About the size of a fist
  • Weight: 280-340 gr for adult males, 230-280 gr for women
  • 12 length x 9 cm in width x 6cm front-back diameter

  
• Position of Heart in Human Body

  • Has an oblique position in the thorax with 2/3rd to the left of midline
  • Base is located below the third rib as it approaches the sternum
  • Base is directed superiorly to the right of midline and posterior
  • The pointed apex projects to the left of midline and anterior
  • Heartbeat is palpated between the 5th and 6th ribs (just inferior to the left nipple)

  
• 5 Surfaces Of Heart

  • Base/posterior surface
  • Anterior/sternocostal surface
  • Diaphragmatic/inferior surface
  • Right pulmonary surface
  • Left pulmonary surface

  
• Sternocostal Surface of Heart

  • Formed by right atrium and right ventricle
  • Divided by atrio-ventricular groove into atrial part (right atrium) and ventricular part (right 2/3 right ventricle, left 1/3 left ventricle)
  • Ventricles are separated by Anterior interventricular groove which lodges anterior interventricular artery and great cardiac vein
  • The coronary groove lodges the right coronary artery

  
• Diaphragmatic (Inferior) Surface


  • Formed by the two ventricles, mainly left ventricle (left 2/3)
  • Slightly concave & rests on diaphragm
  • Directed inferiorly and backward
  • Separated from base by posterior part of coronary sulcus
  • 2-ventricles are seperated by posteior interventricular groove which lodges posterior interventricular artery and middle cardiac vein
• Base Of The Heart (Posterior Surface)

  • Formed by 2 atria, mainly left atrium, into which open 4 pulmonary veins
  • Directed backwards
  • Lies opposite middle thoracic vertebrae (5-7)
  • Separated from the vertebral column by descending Aorta, esophagus and oblique sinus of pericardium

  
• Right pulmonary surface


  • Formed mainly by the right atrium
• Left pulmonary surface


  • Formed mainly by the left ventricle; it forms the cardiac impression in the left lung
• Borders of the Heart

  • Upper border: slightly oblique, formed by 2 atria, chiefly the left atrium
  • Right border: nearly vertical, formed by right atrium, extends from SVC to IVC
  • Inferior border: nearly horizontal; formed mainly by right ventricle. A small part near the apex is formed by left ventricle
  • Left border: oblique and curved; formed mainly by the left ventricle, and partly by the left auricle
• Heart Structure


  • External layer formed by visceral layer of serous pericardium (epicardium)
  • Middle layer mainly cardiac muscle (myocardium)
  • Inner layer formed by endothelium (endocardium) lining the inner surface
  • Atrial part has relatively thin walls

  
• Right Atrium


  • Has 2 parts: main cavity (atrium proper) and earlike outpouching, auricle
  • Vertical groove, sulcus terminalis, seen on outside at junction between rt. atrium and auricle; crista terminalis on the inside
  • Upper part of sulcus contains SA node
  • Atrium proper is smooth walled
  • Sinus Venarum is the large quadrangular cavity placed between the two venae cavae
  • Auricle is roughened or trabeculated by bundles of muscle fibers, the pectinate muscles
• Openings in Rt Atrium

  • Superior vena cava opens at the upper end
  • Inferior vena cava opens at the lower end
  • Coronary sinus opens between the opening of inferior vena cava and the right atrioventricular orifice
• Interatrial Septum


  • Fossa ovalis, and annulus ovalis lie on the atrial septum, which separates the right atrium from the left atrium
  • Fossa ovalis is a shallow depression that marks the site of the fetal foramen ovale
• Right Atrium


  • The right atrium contracts pushing blood through the right atrioventricular valve into the right ventricle
  • The right atrioventricular/tricuspid valve is between the right atrium and right ventricle
  • It has three cusps/leaflets: anterior, septal, and posterior
• Atrial Septal Defects


  • Incomplete closure of the oval foramen causes the ASD
  • Large ASD permit oxygenated blood from the lungs, from the left atrium through the ASD in to the right atrium (from left to right shunt), causing enlargement of the right atrium and ventricle and dilatation of the pulmonary trunk
  • Many healthy adults still have a small leftover opening in the wall between the atria, sometimes called a Patent Foramen Ovale (PFO)
• Right Ventricle


  • A triangular chamber; receives blood from rt. atrium and pumps it to lungs through the pulmonary trunk & arteries
  • Interior has two parts: rough inflowing part due to muscular ridges called trabeculae carneae, and smooth outflowing part or infundibulum (conus arteriosus) forms the upper conical part
  • Supraventricular crest separates rough part of the chamber from the smooth wall
• Right Ventricle


  • Tricuspid valve guards the right atrioventricular orifice
  • Valve consists of three cusps anterior, septal, and inferior (posterior) cusps
  • Cusps are formed by a fold of endocardium with some connective tissue
  • Prevents regurgitation of blood into the right atrium during ventricular systole
• Right Ventricle


  • Tendinous cords attach to the free edges and ventricular surfaces of the anterior, posterior, and septal cusps
  • Tendinous cords arise from the apices of papillary muscles, which are conical muscular projections with bases attached to the ventricular wall
• Right Ventricle


  • 3 papillary muscles corresponding to cusps of tricuspid valve
  • Ant papillary m: ant & post cusp
  • Post papillary m: post & septal cusp
  • Septal papillary m: ant & septal cusp
  • Function of the papillary m: begin to contract before contraction of right ventricle to prevent ventricular blood from passing back into right atrium
• Right Ventricle


  • Interventricular Septum placed obliquely
  • Upper part thin and membranous
  • Lower part is thick muscular and separates the two ventricles
• Ventricular Septal Defect (VSD)

  • Membraneous and muscular parts of the interventricular septum develop in different times
  • Membraneous part is the common site of ventricular septal defect
  • Blood pressure in the left ventricle is higher than the right ventricle therefore the blood enters right ventricle by passing through this defect. This condition causes pulmonary issues
• Right Ventricle


  • Pulmonary semilunar valve is between the right ventricle and the opening of the pulmonary trunk
  • It has three semilunar cusps/leaflets: (ant, right, left)
  • The pulmonary valve is at the level of the left 3rd costal cartilage
• Left Atrium


  • Quadrangular chamber situated posteriorly
  • Smooth wall except the left auricle containing pectinate m
  • Interior has: Larger smooth-walled part and Smaller muscular auricle containing pectinate muscles
  • 4 pulmonary veins (2 sup. and 2 inf.) entering smooth posterior wall
  • Slightly thicker wall than that of the right atrium
• Left Atrium


  • Receives oxygenated blood from lungs through four pulmonary veins, and pumps it to the left ventricle through the left atrioventricular or bicuspid valve also called mitral valve
  • Ant. & Post cusps
• Left Ventricle


  • Blood enters the left ventricle from the left atrium through the left atrioventricular orifice and then leaves the ventricle through the aortic orifice, where it passes into the ascending aorta
  • Walls of the left ventricle are three times thicker than those of the right ventricle
  • Left intraventricular blood pressure is six times higher than that inside the right ventricle
• Left Ventricle


  • Interior of ventricle shows two orifices: Left AV or bicuspid or mitral orifice, guarded by the bicuspid or mitral valve, and Aortic orifice, guarded by the aortic valve
  • 2 well-developed papillary muscles— anterior and posterior
  • Chordae tendineae from both muscles are attached to both the cusps of the mitral valve
  • The mitral valve is located posterior to the sternum at the level of the 4th costal cartilage
  • Semilunar aortic valve, between the left ventricle and the ascending aorta, is located posterior to the left side of the sternum at the level of the 3rd intercostal space
• Aortic Valve


  • The three cusps are the right coronary, left coronary, and posterior (noncoronary)
  • Behind each cusp, the aortic wall bulges to form an aortic sinus
  • The aortic walls of the right and left coronary sinuses give origin to the right and left coronary arteries, respectively

  
• Autonomic Innervation of the heart

  • Parasympathetic fibers: Vagus nerve, Parasympathetic stimulation slows down the heart rate
  • Sympathetic fibers: lower cervical ganglia and upper thoracic ganglia (T1-T4), Sympathetic stimulation accelerates the heart rate
• Right Coronary Artery


  • SA nodal branch
  • Right Marginal artery
  • AV nodal branch
  • Posterior interventricular artery (Posterior descending)

  
• Left Coronary Artery


  • Anterior interventricular artery ( Left Anterior Descending) LAD
  • Circumflex artery: left marginal artery, Diagonal branches

  
• Distribution of coronary artery

  • Right Atrium: Right coronary artery
  • Left Atrium: Left coronary artery
  • Right Ventricle: Right coronary artery except left portion of the anterior wall receives branches from the left coronary artery
  • Left Ventricle: Left coronary artery except the right portion of the posterior wall receives a branch from right coronary artery
  • Interventricular septum: Anterior 2/3 from the left coronary artery, posterior 1/3 right coronary artery
  • SA & AV node: from the right coronary artery
  • AV bundle: from both right & left coronary arteries

  
• Veins of the heart

  • Great cardiac vein
  • Middle cardiac vein
  • Post vein of Left vent
  • Oblique vein of left atrium
  • Small cardiac vein
  • Cardiac veins which drain into the coronary sinus
  • Anterior cardiac veins open directly into the right atrium by crossing the anterior atrioventricular groove, draining the blood from the anterior surface of the heart

  
• Plaque deposits in the coronary artery

  • Coronary artery disease is caused by plaque buildup in the wall of the arteries
  • Plaque is made up of cholesterol deposits
  • Plaque causes the inside of the arteries to narrow over time. This process is called atherosclerosis
• Stent implantation


  • In stent application, the occlusion in the coronary artery is opened by entering through the femoral or radial artery with a catheter, and a stent is placed in this area
• Coronary Bypass


  • In by-pass surgery, great saphaneus vein is used to replace the blocked coronary artery. In this way, blood flow is provided with the new vessel