10. Interior Of Right Atrium
1.Smooth Posterior Part (Sinus
Venarum):
• Development: derived from right horn of sinus venosus
• Tributaries: → SVC opens at the upper end
→ IVC opens at the lower end
→Coronary Sinus……Valve of coronary sinus
→Venae cordis minimi
• Intervenous Tubercle of lower: →directs superior vena caval
blood 2 right atrium during embryonic life….
13. SINUS VENARUM
• occupies posterior wall and
posterior part of right wall of
atrium.
FEATURES
1. opening of svc
2. opening of ivc
3. opening of coronary sinus
4. foramina venarum minimarum
5. intervenous tubercle
14.
15. SVC OPENING
• upper & posterior part of
atrium.
• directed downwards &
forwards.
• conveys blood from upper
parts of body.
• not guarded by valve
16.
17. IVC OPENING
• lower & posterior part of
atrium close to septum.
• conveys blood from lower
part of body.
• opening guarded by a
rudimentary semilunar
valve [eustachian valve] -
formed by duplication of
endocardium containing a
few muscle fibres.
18. CORONARY SINUS OPENING
• Situated between opening of ivc
& right atrioventricular orifice in
lowerpart of interatrial septum.
• Guarded by incomplete semilunar
valve at its lower margin-
THEBESIAN VALVE.
• Av node lies just above the
opening of coronary sinus.
19. FORAMINA VENARUM MINIMARUM
• minute openings of venae
cordis minimi.
• more numerous in septal
wall.
• anterior cardiac veins &
sometimes right marginal
vein open in the atrium
proper through foramina
venarum.
20.
21. INTERVENOUS TUBERCLE
• small conical muscular projection immediately
below opening of svc.
• scarcely visible in human.
• probably regulates the blood flow of svc.
30. 3.Interatrial Septum:
• Development: →derived from Septum primum and
septum secundum
• Fossa ovalis →represents the site of embryonic
septum primum
• Annulus ovalis (Limbus fossa ovalis) →represents
the lower free edge of septum secundum
31. RT.SIDE OF INTERATRIAL SEPTUM
• FOSSA OVALIS
• LIMBUS FOSSA OVALIS
• TRIANGLE OF KOCH
[Triangular area bounded
in front by base of septal
leaflet of tricuspid
valve,behind by antero-
median margin of opening
of coronary sinus,above by
tendon of todaro-av node
lodges in the triangle]
• TORUS AORTICUS
34. TRICUSPID VALVE
• Atrium proper
communicates with rt.
Ventricle through rt av.
Orifice.
• Opening – oval in
shape.Permits tips of
three fingers.
• Guarded by tricuspid
valve.
• Area of rt.Atrium - known
as vestibule of tricuspid
valve.
35.
36.
37. LEFT ATRIUM
• Volume - smaller than
right atrium.
• Situated behind & to
the left side of right
atrium.
• Forms 2/3rd of base of
heart.
42. INTERIOR OF LEFT ATRIUM
• Most of the wall –
smooth.
• Left auricle -network of
musculi pectinati is
seen.
• Posterior wall-receives
openings of 4
pulmonary veins.
43.
44. CLINICAL IMPORTANCE
• POTENTIAL SITE FOR FORMATION OF
THROMBI.
• IN SURGICAL AMPUTATION OF LEFT AURICLE
DURING MITRAL VALVECTOMY OPERATION,
CIRCUMFLEX BRANCH OF LEFT CORONARY
ARTERY MAY BE INJURED.
47. RIGHT VENTRICLE
• Generel Features:
1.Interior has 2 parts
2.Interior has 2 orifices
3.Inflowing part has 3 types of muscular ridges
→Ridges
→Bridges
→Pillars(papillary muscles)
