Atrium cordis (ATRIUM)
- Atrium dextrum - Right atrium
- Atrium sinistrum - Left atrium
- atrium
- right atrium
- External features
- little ear or right auricle
- covers the root of ascending aorta
- partly overlaps the infundibulum of right ventricle
- margins are notched and interior is sponge like
- right border of atrium
- right atrioventricular groove
- separates
- right atrium from the right ventricle
- more or less vertical
- lodges right coronary artery
- small cardiac vein
- Internal features
- smooth posterior part or sinus venarum
- most of tributaries except anterior cardiac vein drain in to it
- superior venacava opens at upper end
- inferior venacava opens at lower end
- guarded by rudimentary valve
- eustachian valve (gate )
- in embryonic life
- directs IVC blood to left atrium
- coronary sinus ( heart tank )
- opens between
- IVC opening and Right atrioventricular orifice
- guarded by thebesian valve
- venae cordis minimae ( small heart veins)
- present in walls of all 4 chambers
- open in to right atrium
- derived from right horn of sinus venosus
- intervenous tubercle of lower
- posterior wall of atrium
- rough anterior part or pectinate part
- derived from primitive artrial chamber
- series of transverse muscular ridges
- called musculi pectinati
- interatrial septum
- derived from septum primum and septum secundum
- fossa ovalis
- annulus ovalis or limbus fossa ovalis
- left atrium
- anterior wall formed by interatrial septum
- 2 pulmonary veins open in to posterior wall
