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HEART
DESCRIBE RIGHT ATRIUM UNDER THE FOLLOWING HEADINGS: BORDERS AND
SURFACES, RELATIONS,EXTERNAL AND INTERNAL FEATURES INCLUDING
OPENINGS, BLOOD SUPPLY AND NERVE SUPPLY, DEVELOPMENT INCLUDING
THAT OF INTERATRIAL SEPTUM ANOMALIES (LE)
Borders and surfaces: entire right border, 1/3rd^ of base, part of sterno-costal surface Relations: Anterior- pericardium, mediastinal surface of right lung, pleura posterior and right- right pair of pulmonary veins posterior and left- left atrium separated by interatrial septum lateral- pericardium, right phrenic nerve, pericardiacophrenic vessels, mediastinal pleura, right lung medial- roots of ascending aorta, pulmonary trunk External features Right auricle- conical muscular projection arises from antero-superior part of atrium Sulcus terminalis- shallow vertical groove runs along right border of heart extending between superior venacava and inferior venacava Internal features Posterior smooth part called sinus venarum โ occupies posterior and right wall of atrium Openings- superior venacava, inferior venacava guarded by Eustachian valve, coronary sinus guarded by Thebesian valve, foramina venarum minimarumAnterior rough part called atrium proper- lies in front of crista terminalis crista terminalis- smooth muscle ridge coinciding externally with sulcus terminalis
musculi pectinati- parallel muscular ridges passing forwards from crista terminalis towards right atrioventricular orifice fossa ovalis- oval depression above and to left of inferior venacava limbus fossa ovalis- sickle shaped sharp margin which surrounds upper, anterior and posterior margins of fossa ovalis triangle of Koch- lodges A-V node. It is bounded by septal leaflet anteriorly, antero-medial margin of coronary sinus and tendon of Todaro superiorly
Relations: three layers of pericardium, lungs and pleura, sternum and costal cartilages. Below 4 th costal cartilage on left side directly related to sternum and costal cartilages. This area is called as cardiac dullness. Features: inbetween the atria and ventricles is the atrio-ventricular groove or coronary sulcus. On the right side it lodges right coronary artery along with small cardiac vein. On the left side it lodges left coronary artery. Between the right and left ventricles is the anterior interventricular groove lodging the anterior interventricular artery along with great cardiac vein. RIGHT ATRIUM (SE) Interior of right atrium Posterior smooth part called sinus venarum โ occupies posterior and right wall of atrium openings- superior venacava, inferior venacava guarded by Eustachian valve, coronary sinus guarded by Thebesian valve, foramina venarum minimarum Anterior rough part called atrium proper- lies in front of crista terminalis crista terminalis- smooth muscle ridge coinciding externally with sulcus terminalis musculi pectinati- parallel muscular ridges passing forwards from crista terminalis towards right atrioventricular orifice
Septal wall formed by interatrial septum fossa ovalis- oval depression above and to left of inferior venacava limbus fossa ovalis- sickle shaped sharp margin which surrounds upper, anterior and posterior margins of fossa ovalis Triangle of Koch- lodges A-V node. It is bounded by septal leaflet anteriorly, antero-medial margin of coronary sinus and tendon of Todaro superiorly INTERATRIAL SEPTUM AND ITS DEVELOPMENT (SE) Interatrial septum fossa ovalis- oval depression above and to left of inferior vena cava limbus fossa ovalis- sickle shaped sharp margin which surrounds upper, anterior and posterior margins of fossa ovalis triangle of Koch- lodges A-V node. It is bounded by septal leaflet anteriorly, antero-medial margin of coronary sinus and tendon of Todaro superiorly Development Septum primum grows from roof and dorsal wall of primitive atrium and runs downwards. A foramen primum is formed between the septum primum and septum intermedium which is later on closed.
proximal bulbar septum which grows downwards and fuses with upper margin of ventricular septum proper Septum intermedium formed by fusion of ventral and dorsal cushions fills the gap between ventricular septum proper and proximal bulbar septum LEFT ATRIUM (SE) It forms most of the base;part of left surface and left border of heart. The tubular muscular projection from the atrium forms the left auricle overlapping the pulmonary trunk. Interior : larger smooth walled part and smaller muscular auricle containing the musculi pectinati Four pulmonary vein open into the smooth posterior wall The wall is slightly thicker than the right atrium It communicates to left ventricle through the left atrio-ventricular orifice which has two cusps
LEFT VENTRICLE (SE)
It forms the apex, most of the left surface and border and most of the diaphragmatic surface of heart. Interior: Wall is three times thicker than that of the right ventricle. Smooth outflowing part- non muscular part called aortic vestibule leading to aortic orifice and valves Rough inflowing part- presents with trabeculae carneae โ ridges (muscular elevation attached throughout to the ventricular wall), bridges (both ends of muscular elevation attached to ventricular wall with a gap inbetween) and papillary muscles (conical muscular projections with bases attached to ventricular wall and apex giving attachment to chordae tendinae) Atrio-ventricular orifice or mitral orifice- it has two cusps anterior and posterior. Each cusp gives attachment to chordae tendinae. The chords become taut just before the systole preventing the cusps from being forced into left atrium. The cusps prevent the backflow of blood into left atrium.
TRIANGLE OF KOCH (SA)
It lodges A-V node. It is bounded by septal leaflet anteriorly, antero-medial margin of coronary sinus inferiorly and tendon of Todaro superiorly CHAMBERS OF HEART FORMING BASE OF HEART (SA) 2/3rd^ of the base is formed by left atrium and 1/3rd^ is formed by right atrium. It is bounded on right side by sulcus terminalis extending from superior venacava to inferior venacava, left side by left superior and inferior pulmonary veins, above by the bifurcation of pulmonary trunk and below by atrio-ventricular groove CRISTA TERMINALIS (SA) It is a muscular ridge extending from superior venacava to inferior venacava inside the right atrium opposite to sulcus terminalis. Muscular ridges arise from crista terminalis extending towards the right auricle forming musculi pectinati. It separates the smooth part from the rough part of right atrium. OPENINGS OF RIGHT ATRIUM (SA) Superior venacava- opens from above into posterior part of right atrium inferior venacava- opens from below into posterior part of right atrium. It is guarded by the Eustachian valve which in fetal life directs the blood flow towards the left atrium. coronary sinus- opensinto right atrium inbetween the opening of inferior venacava and the right atrio-ventricular orifice. The opening is guarded by the Thebesian valve foramina venarum minimarum- these are small openings which drain blood from the heart seen in the septal wall FOSSA OVALIS (SA) It is the oval depression present on the septal wall of right atrium above and to left of opening of inferior venacava. The floor of fossa is thin and is formed by septum primum.
The superior, anterior and posterior margins of the fossa ovalis is bounded by sharp margin called limbus fossa ovalis. PAPILLARY MUSCLES (SA) They are the conical muscular projections present in the right and left ventricles. Each papillary muscle has an apex which is free and the base attached to the ventricular wall. Apex gives rise to the chordae tendinae. There are three papillary muscles in the right ventricle (anterior, posterior, septal) and two in the left ventricle (anterior, posterior). When the papillary muscles contract, the chordae tendinae becomes taut and pulls the cusps closer to each other and prevents the backflow of blood into atria. BLOOD SUPPLY,NERVE SUPPLY AND CONDUCTING SYSTEM OF THE HEART (LE) DISCUSS THE BLOOD SUPPLY OF THE HEART AND ADD A NOTE ON THE PERICARDIAL SINUSES.(LE) DESCRIBE BLOOD SUPPLY OF HEART.GIVE ITS APPLIED ANATOMY.(LE) LEFT CORONARY ARTERY (SE) RIGHT CORONARY ARTERY (SE) The heart is supplied by the right and left coronary arteries. Right coronary artery : Arises from the anterior aortic sinus of the ascending aorta.
Area of distribution: Left atrium. Ventricles Greater part of the left ventricle. A small part of the right ventricle. Anterior part of the interventricular septum. A part of the left branch of the AV bundle. Venous drainage: About 60% of the venous blood of the heart drains into the right atrium via the coronary sinus. The remaing 40% drains into the different chambers of the heart via venae cordis minimi and anterior cardiac veins. The tributaries of the coronary sinus are The great cardiac vein. The middle cardiac vein. The right marginal vein. The posterior vein of the left ventricle. The oblique vein of the left atrium. The right marginal vein Applied Anatomy: Ischaemic heart disease Results from occlusion of coronary artery or its major branches. Myocardial infarction : Due to sudden and complete obstruction of a major branch of coronary artery,the heart failure occurs. It is also known as heart attack.
Angina pectoris : Due to incomplete and spasmodic obstruction of coronary arteries. ,there will be pain in the left side of the chest which aggravates on exsertion. PERICARDIAL SINUSES: (LE) Transverse sinus: It is transeverse passage between two tubular reflections of the serous pericardium. It is lined by visceral layer only. Boundaries: Infront - Ascending aorta and pulmonary trunk enclosed in a single tube of serous pericardium. Behind - Intra pericardial part of superior venacava and upper margin of the left atrium. Above- bifurcation of pulmonary trunk. Below- Upper surface of left atrium. Oblique sinus: It is a cul de sac behind the left atrium. It is closed on all sides except below. It is placed between parietal and visceral layers.
Infront: Upper & lower end of body of sternum by superior and inferior sternopericardial ligament respectively. Structure piercing: Ascending aorta Superior & inferior vena cava. Right and left pulmonary aarteries. Four pulmonary veins. Serous pericardium It is thin double layred serous membrane lined by mesothelium. It is having two layers-outer parietal pericardium
- inner visceral pericardium. The parietal pericardium lines the inner surface of fibrous pericardium & intimately blended with it. Visceral pericardium covers the heart and roots of great vessels attatched to the heart. PERICARDIAL SINUSES : (SE) Transverse sinus : It is transeverse passage between two tubular reflections of the serous pericardium. It is lined by visceral layer only. Boundaries: Infront - Ascending aorta and pulmonary trunk enclosed in a single tube of serous pericardium.
Behind - Intra pericardial part of superior venacava and upper margin of the left atrium. Above - bifurcation of pulmonary trunk. Below - Upper surface of left atrium. Oblique sinus: It is a cul de sac behind the left atrium. It is closed on all sides except below. It is placed between parietal and visceral layers. Boundaries : In front - left atrium Behind - parietal layer,covering the posterior part of fibrous pericardium. Right side - right pair of pulmonary veins and inferior vena cava. Left side - left pair of pulmonary veins. Above- upper margin of left atrium. FIBROUS PERICARDIUM (SE) It is a cone shaped sac made up of fibrous tissue. Attachments: Above its apex blends external coat of ascending aorta and pulmonary trunk.it is continues with pre tracheal layer of deep cervical fascia. Below The upper surface of central tendon and a part of musculature of the left part of the diaphragm. Infront Upper & lower end of body of sternum by superior and inferior sternopericardial ligament respectively.
Features within the serous pericardium are Transverse sinus. oblique sinus. : Arterial supply: Parietal layer is supplied by branches of internal thoracic artery. And descending thoracic aorta. Visceral layer by coronary arteries. Venous drainage: Parietal layer drain into azygous and internal thoracic vein. Visceral layer drains into coronary sinus. Nerve supply: Parietal layer by phrenic nerve. Visceral layer by vagus and sympathetic nerve.
Area of distribution: Left atrium. Ventricles Greater part of the left ventricle. A small part of the right ventricle. Anterior part of the interventricular septum. A part of the left branch of the AV bundle. VENOUS DRAINAGE OF HEART. (SE ) CORONARY SINUS-FORMATION ,COURSE AND TRIBUTARIES.(SE) Venous drainage: About 60% of the venous blood of the heart drains into the right atrium via the coronary sinus The remaing 40% drains into right atrium by anterior cardiac veins and other chambers via venae cordis minimi. The tributaries of the coronary sinus are The great cardiac vein. The middle cardiac vein. The right marginal vein. The posterior vein of the left ventricle. The oblique vein of the left atrium. The right marginal vein. Anterior cardiac veins These are 3 or 4 in number, drain the infundibulum of the right ventricle, and end directly into the right atrium through the foramina minimarum. Venae cordis minimi : These veins open into different chambers of the heart through the foramina minimarum.
