Right Atrium of Heart: Interior Structure

RIGHT ATRIUM OF HEART : INTERIORThe interior of right atrium consists of 2 parts:APOSTERIORSmooth part-known as sinus venarion(B)ANTERIORRough part.Human ForThese 2 parts are separated by a smooth muscidar nidge. theerista terminalis.DESCRIPTION(A)POSTERIOR SMOOTH PARTDIPANUAR RAYThis part receives the great veins (Superior and inferior vena caraand the coronary Sinus) and represents the confluence of veinsor Sinus venosus of the embryo(a)DIFFERENT OPENINGS1.) OPENING OF SUPERIOR VENA CAVAi) Situation :-Post superior part of arium Rt. (ii) Direction :-Downwards and(iii) Valve :- No Valve.forwards.2OPENING OF ANFERIOR VENA CAVA(a) Situation:- Lower and posterior part of right atrium near theinter-atrial septum.(b) Valve:- (i) Situation - Infant of orifice of Inferior vena cava.(iii) Shape - Semilunar(iii) Formation -By duplication of lining membrane of atriumenclosing few musculard fibres.(iv) Margins - Vara consist of 2 margins:I Convex MarginII Concave MarginAttached to ant marginLt horn :- - Continuos with the limbusof orificefossa roralis.153OPENING OF CORONARY SINUSRt ham:- Continuous with theCristerminalis.a Situation :- Opening is placed between the orifice of inferiorvena tara and right ario-ventricular orifice.b Valve :- Situsation:- The superior extremity of the valve ofof coronary sinus and separates from the fossa ovalis.inferior vena cava is to the right of the valve RIGHT ATRIUM : INTERIOR SIDE HEART2Formation:(ii) Shape Semilunar (iii) By semilunar fold of the lining memberareof atrium.(iv) Function:- Prevents regurgitation of blood into the Sinusduring the contraction of atrium.4RIGHT-ATRIVENTRICULAR ORIFICEHuman AnatomyFor ExamaSituation:- Situated between night atrium and right ventricle,at the base of venticle.(b) Encircled by:- Fibrous ring which gives attachment to the capsSkeleton of heart., which surrounds both A.V. orifices and also theof rt atrioventricular valve. This ring is part of fibrouspulmonary and aortic orifices.DIPANKAR_RAY(c) Valvae:- Valve consists of 3 casps and are named fromtheir position.CapsI1 FORMATION :- By duplicature of lining membrane of heart.(ii) FEATORES:-athin and translucent.Central part thick and strong; marginal portion(b) SURFACE :- (i) Arrial Surface:- Smooth; directed towards theblood circulation from the atrium.(ii) Ventricular Surface:- Rough and irregular; directed towardsthe wall of ventricle.CBASE:- of each casp attached to the ring surrounded theA.V. orifice.dAPEX and MARGINS :-Attached to a number of delicate tendeniouscord, which are known as chardae tendinae(iii) NUMBER:- 3 casps - Anterior, Posterior and Septal. RIGHT ATRIUM : HEART: INTERIOR3(b)THE SURFACE OF THE ATRIAL SEPTOM LOOKING TOWARDS RIGHT ATRIUM1.FOSSA OVALIS(i) Definition: It is an oral depression on the lower partand to the left of orifice of Inferior vena cara.of the septal wall of the atium, above(ii)Formation :- Formed by the septum primum of the factal heart2.LIMBUS FOSSA OVALISDIPANKAR RAYHuman AnatomyFor Exam(i) It is a ridge guarding the upper part and sides of fossa-oralis.(ii) It has posterior limb, connecting limb and anterior limb belowit is deficient.(iii) Anterior limb is continuous with the left horn of inferiorvera cara.3 (iv) FORAMEN Developed OVALE from free margin of septum Secondum.(i) It represents the persistent osteum secondum due to failureof fusion of septum primum and Secondum.(ii) Situated above fossa oralis and overlapped by limbus fossaOralis(iii) If it is present blood will flow from left to right atriumbecause in left atrium there is higher arterial pressurethan the venous pressure in the right atrium.4 INTERVENOUS TUBERCLE(i) Definition :- It is a slight angulation in posterior wall of Rt atrium-(ii) Situation :- Below the orifices of S.v.e. and superior to F. ovalis.(iii) Function:- During foetal life its function is to direct the S.V.canal blood towards the right A.V. orifice.5.FORAMINA VENARUM MINIMARUMThese are the urifices for venae cordue minimae. RIGHT ATRIUM HEART : INTERIOR4(8)ANTERIOR ROUGH PARTPRESENTS MUSCULI PECTINATIDIPANKAR RAYThese are panallel muscular ridges runs forwards from theCrista-terminalis across the lateral and anterior wall ofright atrium, inclining towards the atrio-ventricular orifice.(c)CRISTA TERMINALLSHuman Anatomy For Exam(i)DEFINATIONIt is a smooth muscular ridge in the inner aspectpost. smooth part from ant rough part. It corresponds toof the lateral wall of rt atrium, separating theSulsus terminalis in the external surface of rt. atrium-ii)EXTENTIt starts from the upper part of atrial septumand descends on lateral wall of right atrium upto the orificeand passes anterior to the opening of S.V. cavaof I.V.C. , where it continuous with right born of concavemargin of I.V. caral valve.