Pericardium Conical fibro serous sac Situated in the

Pericardium © Conical fibro serous sac © Situated in the middle mediastinum © Encloses the heart and roots of great vessels © Composed of two layers © Fibrous layer © Serous layer

Fibrous pericardium © Conical sac made up of fibrous tissue © Apex - tunica adventitia of great vessels and continuous with pre-tracheal layer © Base- central tendon of diaphragm Both of them developed from the septum transversum

© Anteriorly- attached to the posterior surface of the sternum by superior and inferior sterno - pericardial ligaments © Behind related to the posterior mediastinum © On each side related to mediastinal pleura

Serous pericardium © Closed sac lies within fibrous pericardium © Consist of visceral and parietal layers © Parietal layer lines the fibrous pericardium © Visceral layer (epicardium) covers the heart and roots of great vessels © Pericardial cavity contains serous fluid © Lined by mesothelium

Sinuses of pericardium © The continuity between parietal and visceral layers is established in the form of two tubes © Arterial tube © Venous tube

Transverse sinus © Transverse passage between the arterial and venous ends of heart tubes © Developed from the degeneration of central cells of dorsal mesocardium

Boundaries • Anteriorly • Posteriorly • Inferiorly • On each side

Oblique sinus

Blood supply Arterial supply: © Fibrous and parietal layers – branches of internal thoracic and descending thoracic aorta © Visceral layer – coronary arteries Venous drainage: © Fibrous and parietal layers – internal thoracic and azygos veins © Visceral layer – coronary sinus

Nerve supply © Fibrous and parietal layer – phrenic nerves © Visceral layer – vagus and sympathetic nerves

Applied anatomy

Surgical significance of transverse sinus: Ligature may be passed through the sinus around the aorta and pulmonary trunk to control hemorrhage during cardiac surgery

©Surgical significance of transverse sinus: © Ligature may be passed through the sinus around the aorta and pulmonary trunk to control hemorrhage during cardiac surgery

Pericarditis © Inflammation of serous pericardium © Causes chest pain © Serous pericardium may become rough © Pericardial friction rub may be heard with stethoscope over the left sternal border

Pericardial effusion

© Excess pericardial fluid compress the heart and decreases the diastolic capacity © Reduces cardiac output Pericardial tamponade

Pericardiocentesis: © Drainage of fluid from the pericardial cavity to relieve cardiac tamponade

HEART

HEART YMuscular YLocated YPlaced organ in the middle mediastinum obliquely behind body of sternum, costal cartilages

HEART YWeighs approx 300 g in males, 250 g in females Y Has four chambers Y Two atria Y Two ventricles

EXTERNAL FEATURES Y Atrioventricular groove (coronary sulcus) Y Interatrial groove Y Interventricular groove Y Auricles – extensions of each atria

EXTERNAL FEATURES APEX Y Formed by the left ventricle Y Located in the left 5 th intercostal space Y Just medial to the midclavicular line

EXTERNAL FEATURES BASE Y Forms the posterior surface Y Formed by the left atrium and a small part of the right atrium Y Openings of four pulmonary veins Y Openings of superior and inferior vena cavae

SURFACES AND BORDERS Y Surfaces: Y Y Anterior (Sternocostal) Y Inferior (diaphragmatic) Y Right Y Left Borders: Y Superior Y Inferior Y Right Y Left

Y Upper border- by two atria YRight border- by the right atrium Y Inferior border- by the right ventricle and left ventricle Y Left border- by the left ventricle and partly by the left auricle BORDERS

STERNOCOSTAL SURFACE YFormed mainly by the right atrium and right ventricle Y Partly by the left ventricle and left auricle YSuperficial cardiac dullness SURFACES

DIAPHRAGMATIC SURFACE Y Rests on the central tendon of the diaphragm Y Formed by the right & left ventricles YPosterior groove interventricular SURFACES

SURFACES LEFT SURFACE YFormed by left ventricle & left auricle Y Coronary sulcus

RIGHT ATRIUM Y Receives venous blood from the whole body Y Pumps it to the right ventricle through the tricuspid orifice

RIGHT ATRIUM YElongated vertically YUpper end is prolonged and forms right auricle Y Shallow vertical groove – sulcus terminalis YCorresponds to the internal muscular ridge – crista terminalis Y Contains the sino-atrial node – pacemaker of the heart Y Right atrioventricular groove

RIGHT ATRIUM Right atrioventricular orifice Y Called tricuspid Y Guarded by a valve with three leaves/cusps Y Maintains the unidirectional flow of blood

RIGHT ATRIUM Y Inlets: Y Superior vena cava Y Inferior vena cava Y Coronary sinus Y Anterior cardiac veins Y Venae cordis minimi

RIGHT ATRIUM – INTERNAL FEATURES Y Divided into three parts Y Smooth posterior wall – sinus venarum Y Rough anterior wall – pectinate part Y Septal wall

Y Most of the tibutaries open into it YSVC – upper end Y IVC – lower end – guarded by a rudimentary valve Y Coronary sinus – between the IVC and Rgt. AV orifice – guarded by the Thebesian valve Y Intervenous tubercle of Lower SINUS VENARUM

Y Transverse muscular ridges – musculi pectinati Y Extends from crista terminalis to RAVO Y Forms a comb-like appearance Y Extends into the right auricle to form a reticular network PECTINATE PART

YShallow oval depression – fossa ovalis YFormed by septum primum Y Prominent upper border of the fossa – limbus fossa ovalis Y Formed by the lower border of septum secundum Y Remains of foramen ovale SEPTAL PART

RIGHT VENTRICLE Y Receives blood from the right atrium Y Pumps it through the pulmonary trunk to the lungs Y Forms the inferior border, sternocostal surface, small part of the diaphragmatic surface

RIGHT VENTRICLE-INTERNAL FEATURES Y Inflowing part – muscular ridges - trabeculae carneae Y Outflow part (infundibulum) is smooth-leads to pulmonary trunk Y Ridge separating the two parts – supraventricular crest Y Two orifices: Y Right atrioventricular Y Pulmonary

RIGHT VENTRICLE YTrabeculae carneae- three types Y Ridges (fixed) Y Bridges Y Papillary muscles YAnterior – largest Y Posterior/Inferior – small and irregular Y Septal – small nipples

RIGHT VENTRICLE YChordae tendinae – Strings that connect the tips of the papillary muscles to the cusps YEach papillary muscle is attached to two contiguous cusps Y Septomarginal trabecula (moderator band) Y Wall is thinner than that of the left ventricle

LEFT ATRIUM Y Forms the left 2/3 of the base of the heart Y Receives oxygenated blood from the lungs through four pulmonary veins Y Pumps the blood into the left ventricle through the left atrioventricular orifice

LEFT ATRIUM INTERNAL FEATURES Y Anterior wall is formed by the interatrial septum Y Posterior wall receives the four pulmonary veins YMusculi pectinati are present only in the left auricle Y Fossa lunata – formed by septum secundum

LEFT VENTRICLE YReceives oxygenated blood from the left atrium Y Pumps it out through the aorta YInflow part- trabeculae carneae Y Smooth part – vestibule – leads to the aorta

LEFT VENTRICLE Y Two orifices Y Left atrioventricular (mitral) Y Aortic Y Two papillary muscles Y Anterior Y Posterior Y Walls are three times thicker than right ventricle

Y Two parts – lower muscular, upper membranous YBulges into the cavity of the right ventricle INTERVENTRICULAR SEPTUM

VALVES OF THE HEART Y Maintain unidirectional flow of blood Y Prevents regurgitation Y Two pairs of valves YAtrioventricular YSemilunar

ATRIOVENTRICULAR VALVES

TRICUSPID VALVE Y Three cusps – anterior, posterior and septal

BICUSPID VALVE Y Two cusps – anterior and posterior

SEMILUNAR VALVES Y Shape of the cusps Y Each has 3 cusps, attached to the walls of the vessel

SEMILUNAR VALVES Y Each cusp forms a small pocket Y Free margin contains a central nodule Y From each side of the nodule, a thin smooth margin – lunule

HISTOLOGICAL STRUCTURE OF THE HEART Three layers Y Endocardium – endothelium and subendothelial connective tissue Y Myocardium – Thickest layer of the wall Y Epicardium – visceral layer of serous pericardium

NERVE SUPPLY TO THE HEART Y Cardiac plexus – can be divided into superficial and deep Y SYMPATHETIC Y Preganglionic passing through T 2 -T 5 ganglia Y Postganglionic passing through the cervical and upper thoracic ganglia Y Cardio-acceleratory

NERVE SUPPLY TO THE HEART Y PARASYMPATHETIC Y Vagus Y Cardio inhibitory

NERVE SUPPLY TO THE HEART Y Superficial cardiac plexus Y Below the arch of aorta, in front of right pulmonary artery Y Superior cervical cardiac branch of left sympathetic chain Y Inferior cervical cardiac branch of left vagus

NERVE SUPPLY TO THE HEART Y Deep cardiac plexus Y Behind the arch of aorta, in front of bifurcation of trachea Y Cardiac branches derived from cervical and thoracic ganglia of sympathetic chain Y Cardiac branches from vagus and recurrent laryngeal nerves

CONDUCTING SYSTEM OF THE HEART

ARTERIAL SUPPLY TO THE HEART Y Two arteries – right and left coronary arteries Y Inner (100 µm) endothelial surface by blood in the chambers Y Anatomically- not end-arteris Y Functionally- end-arteries

RIGHT CORONARY ARTERY

Y Arises from the right anterior aortic sinus Y Emerge on surface of heart b/w pulmonary trunk and right auricle Y Runs in right anterior coronary sulcus Y Winds around inferior border to reach posterior coronary sulcus Y Terminates by anastomosing with leftcoronary artery Course

Branches Y Marginal branch Y Posterior interventricular branch Y Nodal branch- 60% cases Y Right atrial Y Infundibular Y Terminal

Distribution Y Right atrium Y Greater part of right ventricle Y Small part of left ventricle Y Posterior part of interventricular septum Y Whole conducting system of the heart except left branch of AV bundle

LEFT CORONARY ARTERY

Y Arises from the left posterior coronary sinus Y Passes between the left auricle and pulmonary trunk Y Gives anterior interventricular artery Y Continues as circumflex artery in posterior coronary sulcus Course

Branches Y Anterior interventricular branch Y Large diagonal branch Y Left atrial Y Pulmonary Y Terminal

Distribution Y Left atrium Y Greater part of left ventricle Y Small part of right ventricle Y Anterior part of interventricular septum Y Left branch of AV bundle

Cardiac dominance Y 90% cases posses right coronary predominance Y 10% posses left coronary predominance

VENOUS DRAINAGE OF THE HEART Y Venous blood from the heart drained by Y Coronary sinus Y Anterior cardiac veins Y Venae cordis minimi

Y Largest vein YPresent in the left posterior coronary sulcus YDrains into posterior wall of the right atrium Y Guarded by a thebesian valve CORONARY SINUS

Tributaries: Y Great cardiac vein - accompanies anterior interventricular artery Y Middle cardiac vein- accompanies posterior interventricular artery Y Small cardiac vein- accompanies the right coronary artery Y Oblique vein of the left atrium YPosterior vein of left ventricle YRight marginal vein CORONARY SINUS

ANTERIOR CARDIAC VEINS § Begin over the anterior surface of the right ventricle § 3 -4 in number § Usually open in the right atrium

VENAE CORDIS MINIMI Ø Smallest cardiac veins Ø Open directly into all the chambers Ø Numerous on the right side

LYMPHATIC DRAINAGE Ø Accompany the coronary arteries and form two trunks Ø Right trunk- brachiocephalic nodes Ø Left trunk- tracheobronchial nodes

Applied anatomy

Coronary heart disease Y Sudden and complete occlusion (block) of branches of coronary arteries lead to necrosis of the cardiac muscle-myocardial infarction Y Caused by thrombosis and chronic atherosclerotic narrowing of lumen

Frequency of occlusion Y Anterior interventricular artery- 40 -50% Y Right coronary artery- 30 -40% Y Circumflex artery- 15 -20%

Angina pectoris Y Incomplete occlusion of branches of coronary arteries- Cardiac pain Y Pain fibres conveyed by sympathetis cardiac nerves- T 1 -T 5 spinal segments

YPrecordium YTachycardia YBradycardia YArrhythmia YMyocarditis, endocarditis, pericarditis

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