Heart Anatomy PDF

Cardiovascular system Cardiovascular system Lymphatic system Circulatory system Body fluid‘s system: cerebrospinal fluid- liquor, aqueous humor, synovial fluid, perilymph, endolymph, serous fluid  Heart  Blood vessels  Cardiovascular system Functions  Distribution...

Cardiovascular system Cardiovascular system Lymphatic system Circulatory system Body fluid‘s system: cerebrospinal fluid- liquor, aqueous humor, synovial fluid, perilymph, endolymph, serous fluid  Heart  Blood vessels  Cardiovascular system Functions  Distribution of O2 and nutrients: glucose, amino acids to body tissue  Transportation of CO2 and waste products to lungs and excretory organs  Distribution of water, electrolytes, hormones in body  Contribution to immune system  Thermoregulation Heart L. cor, G. kardia Fibromuscular, hollow organ 300 (280-340) g Self-initializing, self-adjusting pump!  Position of the heart Mediastinum Upper: trachea, oesophagus, thymus, aa., vv., nn. Lower: Anterior: thymus, aa., vv., nn. Middle: heart, pericardium Posterior: oesophagus, aa., vv., nn. The heart is situated obliquely in the middle mediastinum, and is located about 2/3 to the left and 1/3 to the right of it.  Heart is located in pericardial sac Pericardium Fibrous pericardium Serous pericardium  Parietal layer- serous sac  Visceral layer- epicardium Pericardial cavity Pericardial sac is posterior to the sternum, between the 2nd to 6th costal cartilages or anterior to T5 to T8 vertebrae  Fibrous pericardium  more or less conical outer sac!  is the tough, collagenous connective tissue, is without being connected to heart!  protects the heart against sudden overfill  is anchoring heart in its position  it’s upper part is pierced by the aorta, pulmonary trunk, and superior vena cava  caudal part rests on and is fused with the central tendon of the diaphragm  it is attached anteriorly to the posterior surface of the sternum by week sternopericardial ligaments  it is also fused with adventitia of the great vessels and loose connective tissue of mediastinal pleura  fibrous pericardial sac is influenced by movements of the thoracic wall, diaphragm, and heart  1 Serous 2 pericardium  transparent, consists of two layers: parietal (1) and visceral (2)!  visceral pericardium is reflected onto the heart where it forms the epicardium - the external layer of the heart wall  visceral pericardium is reflected from the heart and great vessels to become continuous with the parietal pericardium  parietal layer is fused to interior of the fibrous pericardium and is closely adherent to it, so separation is difficult  potential space between the parietal and visceral layers is pericardial cavity  cavity normally contains a thin film of serous fluid- 10-20 ml interstitial fluid-lubricant, that enables the heart to move and beat in a frictionless environment Note: The fluid may collect in pericardial cavity- pericardial effusion. Following fibrinous inflammation adhesions can give restricting motion of the heart! Rupture of aorta- will cause a rapid blood pass to cavity - pericardial tamponade!  Surface anatomy of the heart (projection onto anterior chest wall) Borders  Superior horizontal line between third costal cartilage junction to sternum  Right (right atrium)- between third and fifth right costal cartilages approximately 3 cm from the midline, or 1- 2 cm from right sternal margin  Inferior (right atrium, right ventricle, left ventricle- apex ) from fifth right costal cartilage to the apex, which usually lies behind the fifth left intercostal space 8-9 cm from midline or 1 cm to right from left midclavicular line (The apex beat - it is point of maximal pulsation or the lowest, most lateral point at which pulsation can be felt)  Left (left ventricle, left auricle)- slopes upwards and medially from heart apex to the left third costal cartilage junction with bony part approximately 3 cm from midline or 1.2 cm from left sternal margin The heart has  base  apex  surfaces: sternocostal (anterior), diaphragmatic  margins: right, left, inferior  four chambers: each half (left-arterial and right-venous) consists of  an atrium (L. antechamber) - a receiving area, that pumps blood into  a ventricle (L. little belly) - a discharging chamber  external sulci- coronary, anterior and posterior interventricular sulci Base  is located between coronary sulcus and bifurcation of the pulmonary trunk  is form by right atrium, left atrium and proximal parts of great vessels Great vessels on base  Superior vena cava  Inferior vena cava  Pulmonary veins (4)  Aorta  Pulmonary trunk Composition of the heart  Stroma- fibrous skeleton  Parenchyma- myocardium fibers Wall of the heart 3 layers:  Epicardium- external, serous pericardium  Myocardium- middle, muscular layer  Endocardium- internal, endothelial lining of interior of the heart Fibrous skeleton (fibrous rings) of the heart  it is fibrous connective tissue network of collagen and elastic fibers  it consists of fibrous rings, which encircle the orifices of aorta and pulmonary trunk, atrioventricular orifices Functions:  keeps the orifices patent, prevents them from overly distended  provides attachment for valves  provides attachment for myocardium layers  separates electrical impulses of atria and ventricles Fibrous rings- annuli fibrosi and triangles In the valve plane:  Right fibrous ring  Left fibrous ring  Aortic fibrous ring  Pulmonary fibrous ring Right fibrous triangle Left fibrous triangle Essential components of the fibrous skeleton. Color-coded computed tomographic (CT) images show basal views of the heart after removal of the atria (superior ventricular views) and removal of the ventricles (inferior atrial view). Essential components of the fibrous skeleton include the fibrous aortic-mitral continuity, right and left fibrous trigones, membranous septum, interleaflet triangles, parts of the mitral and tricuspid annuli, tendon of Todaro, and conus ligament. L = left coronary sinus, N = noncoronary sinus, R = right coronary sinus. Fibrous Skeleton of the Heart: Anatomic Overview and Evaluation of Pathologic Conditions with CT and MR Imaging. Farhood Saremi , Damián Sánchez-Quintana, Shumpei Mori, Horia Muresian, Diane E. Spicer, Cameron Hassani, Robert H. Anderson, 2018 Myocardium: Cardiomyocytes (myocardiocytes) Distinguishing feature!  cellular bridges- intercalated discs, which anchor cardiac muscular cells together, allow free passage of ions, and enable the rapid transmission of electrical impulses  functional syncytium 2 types of cardiomyocytes:  contracting myocardium- 99%  specialized cardiomyocytes of conduction system  Atrial myocardium- 2- 4 mm Superficial layer Deep layer  extends over both atria!  particular for each atria!  circular and transverse fibers!:  longitudinal fibers! forms inter-atrial septum  attaches on atrioventricular fibrous rings Muscular structures of the atria-  Pectinate muscles  muscular bundles of parallel ridges in the internal surface of auricle – resembling the teeth of comb  produce atrial natriuretic hormone- to lower the blood pressure by increasing excretion of water and sodium ions in the kidneys, regulates the vascular tone! Ventricular myocardium Right chamber is thinner walled- 5-8 mm than left chamber- 10-15 mm Right ventricle: low pressure pump Left ventricle: high pressure pump 3 layers of myocardium: Outer layer - common for both ventricles, originates from anterior part of AV rings, descends obliquely from right to left to apex and creates vertex, than ascends back to AV rings as inner longitudinal layer in the left ventricle. It creates papillary muscles and trabeculae carneae in left ventricle! Middle layer- fibers are parallel to AV rings, originates from AV rings! 3 types of muscular fibers:  circular fibers- separable encircled ventricles!  ‘’S’’ shape fibers- originate from right ventricle, pass in interventricular septum and as circle end in left ventricle  spiral fibers- helical orientation- only in left ventricle!- from anterior part of fibrous ring, 2ᵡ encircled it- thus reinforce left ventricle!  Muscular structures of the ventricles  Trabeculae carneae (1)- irregular muscular elevations (structures), which projects from inner surface of ventricles!, except in the conus arteriosus!- promote non turbulent flow of blood  Papillary muscles (2) - conical structures, to those apices the chordeae tendineae are attached. Size and number of muscles are variable, anterior one is larger 2 1  Septum  Interatrial septum  Interventricular septum: membranous and muscular parts  Valves  are duplicates of endocardium!  are attached to fibrous rings  allow blood to flow in one direction only!  valves open as blood is pumped via the openings 2 types of valves Cuspid valvular complex 1. Cuspid:  atrioventricular orifice  right atrioventricular, tricuspid valve  fibrous ring  left atrioventricular, bicuspid, mitral valve  cusps (leaflets)  chordeae tendineae 2. Semilunar:  papillary muscles  aortic valve  pulmonary valve  Right atriventricular, tricuspid valve  consists of 3 endocardial cusps: anterior (largest), posterior (smallest), and septal  cusp has roughly triangular shape- base is anchored in right ventricle orifice- to the right fibrous ring (maintains the caliber of orifice!)  free margins of cusps are attached to chordae tendineae (tendon like structure)  length and thickness of the tendinous cords are different  chordae tendineae arise from anterior, posterior, and septal papillary muscles  each cusp receives cords from more than one papillary muscle! During ventricular systole the cusps of valve are prevented from prolapsing (inversion) into right atrium as ventricular pressure arises! Left atrioventricular, bicuspid, mitral valve (Bishop’s miter)  consists of 2 cusps: anterior (larger) and posterior  base of cusp is anchored in left fibrous ring, which maintains the caliber of orifice  free margins of cusps are attached to chordae tendineae  tendinous cords arise from anterior and posterior papillary muscles  each cusp receive cords from more than one papillary muscle  cords became taut during systole  Semilunar valves  Pulmonary valve (in pulmonary opening)  Aortic valve (in aortic opening)  valves are composed of three semilunar valvules!  they project into the artery!  each valvule has edge (lunule) and nodulus (thickened point) Note. Semilunar valves opened when ventricle pressure is greater than arterial blood will flow out of the ventricle into the artery until the gradient no longer exists. When the ventricles stop contracting and begin to relax, pressure is higher in artery!- semilunar valves close! Pulmonary valve:  consists of right, left, and anterior valvules  Aortic valve  larger, thicker, and stronger than pulmonary valve!  it consists of right, left, and posterior valvules  between valvules and aortic wall are dilated pockets- aortic sinuses (Valsalva)!  sinuses promote non-turbulent flow into coronary arteries!  valve closes during ventricle diastole- blood flows into coronary arteries! Clinical note! Aortic insufficiency -valve doesn’t close completely- regurgitation of blood during ventricular diastole Stenosis- valve narrows, doesn’t open fully  Right atrium  receives O2 - poor blood from body via inferior vena cava, superior vena cava, and coronary sinus  right auricle  pectinate muscles (horizontal ridges) in the right auricle  crista terminalis- muscular ridge between openings of cava veins  sinus of venae cavae- part of atrium posterior crista terminalis between openings of caval veins  interatrial septum with oval fossa- remnant structure of embryonic oval foramen  orifice of coronary sinus- above septal cusp  sinuatrial and atrioventricular nodes  right atrioventricular orifice  Right ventricle  receives O2 - poor blood from right atrium through atrioventricular orifice  pumps blood to pulmonary route via pulmonary orifice into pulmonary trunk  conus arteriosus lacks trabeculae carneae!  tricuspid valve and pulmonary valve  trabeculae carneae- muscular elevations  papillary muscles- anterior, septal, posterior- cone shaped muscles to which chordae tendineae are anchored Conus arteriosus  Left atrium  receives O2 - rich blood from pulmonary route via openings of 4 pulmonary veins  left auricle with pectinate muscles  interatrial septum  left atrioventricular orifice  Left ventricle  forms apex of heart  is longer and more conical than right ventricle  receives blood from left atrium via left atrioventricular orifice  pumps blood into aorta via aortic orifice with aortic semilunar valve to systemic route  trabeculae carneae, anterior and posterior papillary muscles, chordae tendineae Conducting system Function- initiates and distributes electric impulses- heart depolarizes and contracts in orderly manner from  Sinuatrial node atria to ventricles!  Atriventricular node Autorhythmicity!  Atrioventricular bundle- (His bundle)  Right and left bundles  Purkinje fibers  Atria contract simultaneously,  Atria relax, then ventricles contract Systole - contraction Diastole – relaxation Conducting system 2 nodular structures:  Sinuatrial node- SA -spindle shape – in the right atrium, beneath epicardium! near opening of superior vena cava, superior end of terminal sulcus and right auricle  In the adult human node is 10-20 mm long, and up to 5 mm thick SA node is known as the pacemaker of the heart- initiates and regulates excitation impulse for heart contractions- a heartbeat 60-80 times per minute. Impulse spreads across the atria at 1 m/s Impulses spread through musculature of both atria! causing them to contract and load the ventricles with blood! Atrial musculature transmits signals rapidly to Atrioventricular node- AV- in the right atrium!  is in the interatrial septum between the opening of coronary sinus and septal cusp of the tricuspid valve, above right fibrous ring (anterior of opening of coronary sinus)  AVN has slow conduction- briefly delays the signals- 0.09-0.1 s! Ventricles are electrically isolated from atria - so they don’t contract yet.  Atrioventricular bundle (bundle of His)  penetrates the right fibrous triangle  reaches the superior part of the muscular interventricular septum on side of right ventricle!  divides into right and left bundles (crus) under endocardium!  their peripheral fibers are Purkinje fibers for myocardium of ventricles with fast conduction- 4 m/s, after to epicardium for initiating contraction  Coronary circulation  the heart has its own blood supply system  blood in the chambers doesn’t nourish the myocardium!  the heart is supplied by right and left coronary arteries  almost all venous blood of the heart empties into right atrium via the coronary sinus!  names of veins not correspond to those of arteries!  anastomoses between arteries are not sufficient to maintain perfusion if one side of the coronary circulation is occluded  coronary circulation is capable of developing a good collateral system in ischemic heart disease  Blood flow into the coronary arteries is greatest during ventricular diastole when aortic pressure is highest and it is greater than in the coronaries. Left coronary artery  arises from left aortic sinus  initial stem lies between the pulmonary trunk and left auricle  after short course it divides into branches:  circumflex artery (as continuation of main artery trunk!):  it curves left in the coronary sulcus  but doesn’t descend in the posterior interventricular sulcus!  anterior interventricular artery: descends in the anterior interventricular sulcus  most often affected by disease, blockage in them are known as- Widow Marker  clinicians name it as left descending artery- LDA Left coronary artery supplies  usually supplies a greater volume of the myocardium than the right coronary artery!:  Left atrium  Most of left ventricle  Part of right ventricle  Anterior 2/3 of interventricular septum  His bundle  SA node -40%  Right coronary artery  arises from the right aortic sinus, and then passes between right auricle and right ventricle to the right side of the pulmonary trunk running in the coronary sulcus  it passes vertically downward in the posterior interventricular sulcus toward the apex Artery gives off several branches:  the largest is posterior interventricular artery: it is on the diaphragmatic surface and runs down in the posterior interventricular sulcus  clinicians usually name it as posterior descending artery- PDA! The right coronary artery supplies  all of the right atrium and part of the left  interatrial septum  all of the right ventricle (except a small region of the anterior interventricular septum)  a variable part of the left ventricular diaphragmatic surface  the posterior inferior 1/3 of the interventricular septum  SA (in 60%) and AV (in 80%) nodes  Cardiac veins Heart’s venous blood empties into the right atrium! via coronary sinus!  it is a wide venous channel, 3-5 cm long, returning blood to the right atrium from the whole heart (except for the anterior region of the right ventricle and small parts of the left atrium and ventricle)  Orifice of coronary sinus  orifice is in a crux of heart: cross point of coronary and posterior interventricular sulcus!  to admit the tip of little finger of the owner of the heart!  in opening of coronary sinus is a valve - which prevents regurgitation of blood  Cardiac veins Heart’s venous blood empties into the right atrium! via the coronary sinus! Tributaries to the coronary sinus: great, middle and small cardiac veins!  great cardiac vein - lying in the anterior interventricular sulcus, curves into coronary groove and empties into coronary sinus. It drains blood from areas supplied by LAD.  middle cardiac vein – is lying in the posterior interventricular sulcus, ascending, and empying into coronary sinus  small cardiac vein- lies in the coronary sulcus between the right atrium and ventricle and joins the coronary sinus near opening of coronary sinus Middle and small veins drain blood from areas supplied by RCA.  Circulation routes  Systemic route Pulmonary route:  Pulmonary trunk  Pulmonary arteries  Capillaries  Pulmonary veins  Pulmonary route:  Pulmonary trunk from right ventricle  Pulmonary arteries  In the lung arteries (venous blood) are intrasegmental!  capillaries  In the lung veins (arterial blood) are intersegmental!  4 pulmonary veins are emptying into left atrium Bronchial arteries and veins (as far as respiratory bronchioli) (blood vessels of systemic circulation!