Anatomy of heart Cardiac chambers, anulus fibrosus, cardiac valves Ágnes Nemeskéri 2018 Semmelweis University Department of Anatomy, Histology and Embryology nemeskeri.agnes@med.semmelweis-univ.hu

Human heart Location of heart Cardiac size, shape, external features Latin: cor Greek: kardia Location of heart Cardiac size, shape, external features Chambers of heart – internal features Valves of heart Connective tissue, fibrous skeleton of heart Arrangement of cardiac muscle fibers

1. Location of heart R L Thoracic cavity -mediastinum cardiacum -above the diaphragm – anterior slope -between mediastinal pleurae R L -1/3 of the cardiac mass lies to the right of the midline

Heart X-ray - posteroanterior https://i.pinimg.com/564x/20/89/b5/2089b5471adcd287f0d22c8963d8b571 --cardiac-anatomy-heart-failure.jpg

Axis of the heart: from the apex to center of the base projecting posterolaterally: emerges near the right midscapular line http://www.vhlab.umn.edu/atlas/anatomy-tutorial/graphics/Article-3_Fig2.jpg

Lateral X-ray (chest –lateral view http://2.bp.blogspot.com/-PpdaVYB28I4/VTXIV-hLXsI/AAAAAAAABSo/xIDQMDI56rg/s1600/a517d01679b356_2HEART-Lateral.jpg

Left lateral radiograph with an esophagogram Bal pitvar megnagyobbodás https://radiologykey.com/wp-content/uploads/2015/12/9783131493316_c001_f010.jpg

2. Cardiac shape base: apex pyramid-shaped: base - apex – oblique orientation in the thorax -apex: facing anteriorly and to the left -base: facing posteriorly, to the right Four chambers - muscular pumps - 2 atria -weakly contractile reservoirs -receive venous blood - 2 ventricles -powerful contractility, force the blood into the main arterial trunks base: facing posteriorly, to the right apex

2. Cardiac size, external features auricles Size -from apex to base: ~ 12 cm -broadest transverse diameter: 8-9 cm, 6cm ant-post -weight: 280g – 340g in males (~ 0,45 % of body weight) 230g – 280g in females (~0,40 % of b.w.) Pulm. tr. Surfaces, borders 1. sternocostal surface (anterior) -facing forwards and upwards -right & left ventricles + right atrium & left auricle -left margin (obtuse) -inferior margin (acute) LV RV Grooves anterior interventricular groove coronary groove -coronary groove apex -notch of cardiac apex

Surfaces 1. sternocostal surface (anterior) - facing forwards and upwards - right & left ventricles + right atrium & left auricle - left margin (obtuse) - inferior margin (acute) Anterior (or sternocostal) – Right ventricle. Posterior (or base) – Left atrium. Inferior (or diaphragmatic) – Left and right ventricles. Right pulmonary – Right atrium. Left pulmonary – Left ventricle

2. Diaphragmatic surface 3. Posterior suface -upper border of the heart 2. Diaphragmatic surface (inferoposterior) -largely horizontal -more flat -mainly on the central tendon of diaphragm -coronary groove: border between inferior and posterior s. -slopes down and forwards -ventricles (chiefly the left) -posterior interventricular groove traverses obliquely 3. Posterior (cardiac base)  -faces back and to the right -mainly the left atrium, posterior part of the right atrium -through the pericardium: esophagus! LA RA LV RV CRUX -point of junction of coronary groove (atrioventricular groove) + interatrial groove + posterior interventricular groove -posterior interventricular groove

diaphragmatic surface

4. posterior surface of the heart Base of heart - portion of the heart opposite the apex superior and medially located forms the upper border of the heart lies just below the second rib primarily involves the left atrium, part of the right atrium, and the proximal portions of the great vessels

Right atrium

Right atrium - receives and holds deoxygenated blood from the superior vena cava, inferior v. cava, vv. cardiacae ant., sinus coronarius, small cardiac vein, which it then sends down to the right ventricle (through the tricuspid valve) https://s3.amazonaws.com/classconnection/191/flashcards/8294191/ png/screen_shot_2015-09-21_at_175837-14FF0D7F93378B94528.png Sinuatrial node is located in posterior aspect of the right atrium, next to the superior vena cava. pacemaker cells which spontaneously depolarize to create an action potential cardiac action potential spreads across both atria causing them to contract, forcing the blood they hold into their corresponding ventricles

3. Chambers of heart – right atrium -crista terminalis (terminal crest) -smooth muscular ridge -pectinate muscles -ostium of coronary sinus -anteroinferior part of right atrium: -large oval vestibule leading to the orifice of the tricuspid valve -fossa ovalis -depression -interatrial septum -right auricule (muscular pouch) -posterior vertically elongated part: sinus venarum cavarum -smooth-walled -right atrioventricular orifice

Right atrium Triangle of Koch: helps the surgical orientation! In fetal life, eustachian valve (valve of inf. v. cava) helps direct flow of oxygen-rich blood through the right atrium into left atrium and away from right ventricle Right atrium - from the interatrial septum inferiorly and to the right to the inferomedial part of the inferior vena caval valve - connective tissue fibers, fibroblasts http://theanatomymap.com/wp-content/uploads/2017/04/Learning-Tendon-Of-Todaro-Heart-Anatomy-37-with-Tendon-Of-Todaro-Heart-Anatomy.jpg Triangle of Koch: helps the surgical orientation!

Interatrial septum – right side http://heart.bmj.com/content/heartjnl/103/6/456/F2.large.jpg?width=800&height=600&carousel=1 Oval fossa its floor is represented by septum primum its limbus or margin is represented by septum secundum

3. Chambers of heart – left atrium - smaller in volume than the right, roughly cuboidal left part of it is concealed by the initial segments of pulmonary trunk and aorta - thicker walls (~3mm) - posterior aspect forms most of the base, quadrangular - receives two pulmonary veins from each lung, they open into upper posterolateral surface left auricle – pectinate muscles – longer , narrower than the right auricle vestibule leads to mitral valve -septum has a crescentic ridge (valve of the embyonic foramen ovale) valve of foramen ovale http://content.onlinejacc.org/data/Journals/JAC/23051/08038_gr2.jpeg bal pitvar https://classconnection.s3.amazonaws.com/469/flashcards/919469/jpg/ left_atrium1321061595114.jpg

3. Chambers of heart – ventricles http://www.med.uottawa.ca/patho/eng/public/cardio/nheartshort.gif

3. Chambers of heart – right ventricle septomarginal trabecula RA -„V” –shaped chamber -the anterosuperior cusp of tricuspid valve attaches to the posterolateral aspect of the crest -apical component is coarsly trabeculated -outlet component is smooth -irregular muscular ridges and protrusions: trabeculae carneae, papillary muscles -a protrusionfrom from the septum: septomarginal trabecula supports the anterior papillary muscle, then crosses to the parietal wall

Right ventricle – inlet - outlet http://www.revespcardiol.org/imatges/255/255v63n09/255v63n09-13155686fig1.jpg 1. inlet component: surrounding the tricuspid valve; 2. apical component; 3. outlet or infundibulum (conus arteriosus) -inlet and outlet components are separated in the roof by the supraventricular crest – highly arched from the interventricular septum to the anterolateral right ventricular wall Supraventricular crest separates the inlet and outlet

3. Chambers of heart – left ventricle https://www.researchgate.net/profile/Ismail_El-Hamamsy/publication/264163917/figure/fig2/AS:203027085565953@1425416837335/Photograph-of-an-open-aortic-root-showing-its-structural-components-annulus-cusps.png -wall is 3x thicker than that of right ventricle (8-12 mm) -cone-shaped, longer and narrower than the right ventricle, transversly nearly circular -1. inlet region guarded by the mitral valve; 2. outlet region guarded by the aortic valve; 3. apical trabecular component -in contrast to orifices in right ventricle, in the left: orifices are in close contact, with fibrous continuity interventricular septum : muscular and membranous septum -trabeculae carneae are finer

4. Cardiac valves 1.Atrioventricular – cusped valves 2.Arterial – semilunar valves -they arise from the skeleton of the heart

4. Cusped valves Cusps Chordae tendineae Atrioventricular valvular complex -orifice its associated anulus, cusps, supporting chordae tendineae, papillary muscles 4. Cusped valves Cusps -reduplication of endocardium – collagenous core (fibrosa), fibroelastic tissue surrounds it -continuous at the margin and on the ventricular aspect with the chordeae tendineae -basally confluent with the anular connective tissue 1. basal zone: 2-3 mm, thicker, more connective tissue, vascular, innervated 2. clear zone: smooth, translucent, thinner fibrous core 3. rough zone: thick, opaque, uneven on its ventricular aspect where cordae tendineae attach Chordae tendineae -fibrous collagenous structures, arise from on the tips of papillary muscles -attach to ventricular aspect or free margins of cusps (to fibrosa) -they hold the cusp in position to prevent it from flapping back into the atrium Papillary muscles (musculi papillares) -strong muscular columns – 6-12 tendinous cords arise from the tip

4. Tricuspid valve -roughly triangular orifice -anular connective tissues around the orifice separate the atrial and ventricular myocardium completely except: at the point of penetration of atrioventricular bundle -3 cusps: anterosuperior (largest), septal, inferior) -anterior papillary m. is the largest -posterior papillary m. -septal papillary m. is small

4. Bicuspid (mitral) valve -cuspis anterior (aortic, septal, greater, anteromedial), posterior (fali, ventricularis,smaller, posterolateral) anterior cusp is placed between the inlet and outlet posterior cusp: wider attachment to the anulus -circular orifice smaller than the tricuspid orifice -mitral, tricuspid and aortic orifices are intimately connected centrally at the central fibrous body -anterolateral + posteromedial papillary m.

4.Semilunar valves Semilunar valves Pulmonary valve Aortic valve -nodular thickening at the center of the free edge of each cusp: nodule -lunula: both sides of nodule the edges of cusp are thin, translucent -below the lunula: fibroelastic thickening: linea alba 4.Semilunar valves -pulmonary valve http://www.e-heart.org/Photos/01_Cardiac_Structure _Photos/%C2%A9Aortic%20Valve%20Gross%20640%20x%20440.jpg Pulmonary valve -anterior, right and left cusps Aortic valve -posterior, right, left cusps -at the level of semilunar valves the vessel wall bulges outward: sinus of aorta -coronary arteries arise in the depth of right and left aortic sinuses -aortic valve

5. Fibrous skeleton of heart old statement Cusps of pulmonary valve are supported on a free-standing sleeve of right ventricular infundibulum!! Not all four valves are contained within the fibrous skeleton!!

6. Wall of the heart Epicardium -1. flat mesothelial cells (visceral pericardium) -2. underlying loose connective tissue, contains elastic fibers -arteries, veins of heart, adipose tissue, nerves , ganglia 2. Endocardium -1. innermost layer: flat endothelial cells -2. middle layer: collagen and elastic fibers are compact and arranged in parallel in the deepest part, it contains bundles of smooth muscles -3. subendocardial layer: irregular collagen fibers that merge with the collagen surrounding the cardiac muscle fibers -this layer contains the fibers of the conducting system 3. Myocardium

6. Myocardium

6. Myocardium Ventricles: 3 layers Atria: 2 layers -outer spiraling longitudinal: arising from the cardiac skeleton (mainly fibrous trigones) fibers run towards the apex – they form a whorl: vortex of the heart -inner spiraling longitudinal fibers: trabeculae carneae, papillary muscles -middle circular: strong fibers Atria: 2 layers -inner longitudinal, outer circular

6. Myocardium

Spatial organization of the ventricular myocardial fibers Invited paper Towards new understanding of the heart structure and function Francisco Torrent-Guaspa, Mladen J. Kocicab,*, Antonio F. Cornoc, Masashi Komedad, Francesc Carreras-Costae, A. Flotatsf, Juan Cosin-Aguillarg, Han Wenh „The problem of the macroscopic structure of the ventricular myocardium has remained unsolved since the XVI century,” „Ventricular myocardial band concept (VMB)” „the concept of active diastole”

„Torrent-Guasp proposed a challenging and very important anatomic concept in which both ventricles are considered to consist of a single myocardial band extending from the right ventricular muscle just below the pulmonary artery to the left ventricular muscle where it attaches to the aorta, twisted and wrapped into a double helical coil during evolutionary and embryological development, capable of highly efficient sequential contraction responsible for ventricular ejection and filling „