Chambers Of Heart

RIGHT ATRIUM:
  • 3 components the appendage, the venous part, the vestibule. Forms rt. border of heart
  • Fat-filled groove (sulcus terminalis) corresponding internally to the terminal crest (crista terminalis) can be seen along the lateral wall demarcating the junction between appendage and venous components
  • Torus aorticus is an impression in the cavity of Right atrium
  • Arising from the terminal crest, pectinate muscles spread throughout the entire wall of the appendage, reaching to the lateral and inferior walls of the atrium
  • On the endocardial aspect, the branching and overlapping arrangement of the pectinate muscles is clearly visible.
CristaTerminalis:
  • Superiorly it arches anterior to the orifice of the SVC, extends to the area of the interatrial groove, and merges with the interatrial bundle, commonly known as the Bachman bundle
  • SVC opens into the upper and back part of the atrium and opening has no valve.
  • IVC opens into the lowest part of the atrium, near the atrial septum, and guarded by a rudimentary valve ,Eustachian valve.
  • Coronary sinus between the orifice of the IVC and the AV opening and is protected by a valve of Thebesius
  • Triangle of Koch is delineated posteriorly by the tendon of Todaro running in the Eustachian ridge, anteriorly by the septal leaflet of the tricuspid valve, and inferiorly by the coronary sinus
  • The area between the inferior caval vein and the tricuspid valve is also described as the cavo-tricuspid isthmus.
  • The posterior component is mainly fibrous, whereas the anterior component is the musculature of the atrial vestibule and has a smooth endocardial surface
  • Within this area are marked three isthmuses: paraseptal isthmus ,inferior or central flutter isthmus ,and inferolateral isthmus
  • The inferior isthmus passes through the sinus of Keith (triangle),the atrial wall inferior to the orifice of the coronary sinus 
LEFT ATRIUM:
  • 3 components the appendage, the venous part, the vestibule
  • The venous component receives the pulmonary veins and the vestibular component leads to the mitral valve.
  • The left atrial isthmus between the left inferior pulmonary vein and the MV
  • Walls are composed of one to three or more overlapping layers of differently aligned myocardial fibers with marked regional variations in thickness
  • Posterior part of the left atrium receives the pulmonary veins.
  • Left atrium forms the base of the heart
  • Musculature of the atrial wall extends into the veins to varying lengths, with the longest sleeves along the upper vein
RIGHT VENTRICLE:
  • Right ventricle: the inlet containing the atrioventricular valve, the outlet leading to the arterial valve, and the apical prominent trabecular component
  • Most anteriorly situated cardiac chamber is located immediately behind the sternum.
  • Inlet extends from the hinge line (annulus) of the tricuspid valve to the papillary muscles
  • Leaflets of the tricuspid valve can be distinguished as septal, anterior and mural. Septal leaflet with its cords inserting directly to the ventricular septum is characteristic of the tricuspid valve.TV & PV Share fibrous continuity
  • Anterior wall forms most of the sternocostal surface of the heart
  • The moderator band, is characteristic of the right ventricle .This bridges the ventricular cavity between the body of the septomarginal trabeculation and the parietal wall, giving rise to the anterior papillary muscle along the way
  • Depolarisation of cardiac ventricular muscle starts from Left side of inter ventricular septum
  • Within its musculature runs a major fascicle of the right bundle branch.
  1. Superiorly by the pulmonic valve and inferiorly by the supraventricular crest
  2. Lateral aspect is RV free wall, and the medial aspect is formed by the IVS.
  3. Aortic valve cusps sit squarely within the crescent-shaped septal region of the RVOT and are inferior to the pulmonic valve
  4. Anteroseptal aspect located in close proximity to the LV epicardium, adjacent to the anterior interventricular vein and in proximity to the left anterior descending coronary artery.
  5. Inferior aspect is adjacent to the region of the right coronary cusp, left coronary cusp.
LEFT VENTRICLE:
  • Inlet containing the atrioventricular valve, the outlet leading to the arterial valve, and the apical trabecular component
  • Its outlet overlaps its inlet.
  • Septal hinge line of the mitral valve is further away from the apex, and it does not have a septal leaflet
  • The larger portion of the valve is hinged to the parietal atrioventricular junction, whereas one-third is the span of fibrous continuity with the aortic valve
  • The two leaflets of the mitral valve are disproportionate in size.
  • Apical component of the left ventricle extends from the papillary muscles to the ventricular apex.
  • The trabeculations are finer than those found in the right ventricle.
  • Crista supraventricularis Separate Tricuspid valve & Pulmonary valve and Apex trabeculated both
  • The left ventricular outlet is bordered by the muscular ventricular septum anterosuperiorly and the aortic (anterior) leaflet of the mitral valve posteroinferiorly .
  • The membranous part of the interventricular septum is situated in between Left ventricle and right atrium
  • Like the pulmonary valves, these two sinuses contain small segments of ventricular myocardium within, a source of repetitive monomorphic ventricular tachycardia.
  • LVOT are not divided into subdivisions like RVOT
Exam Question
  • Right ventricle anterior wall forms most of the sternocostal surface of the heart
  • Torus aorticus is an impression in the cavity of Right atrium
  • Left atrium forms the base of the heart
  • The membranous part of the interventricular septum is situated in between Left ventricle and right atrium
  • Depolarisation of cardiac ventricular muscle starts from Left side of inter ventricular septum
  • Crista supraventricularis Separate Tricuspid valve & Pulmonary valve and Apex trabeculated both
  • More prominent trabeculation is of right ventricle
  • TV & PV Share fibrous continuity
  • Base of heart is formed by RA + LA
  • Right border of heart is formed by Right atrium
  • Crista terminalis is present in Right atrium
  • SVC enters into rt. atria

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