Posterior to transverse pericardial sinus-

Ans. is 'c' i.e., SVC Pericardial sinuseso These are parts of pericardial cavity,o The pericardial sinuses areTransverse pericardial sinusIf lies between arterial and venous sleeves of pericardial reflection and connects right and left halves of pericardial cavity with each other.It is boundedAnteriorly by A seen ding aorta and pulmonary trunk.Posteriorly by S upertor vena cava and atria.Above :- Bifurcation of pulmonary trunk.Below ;- Upper surface of left atrium.Obi iqu e pericard ial sinusIt is a large cul-de-sac lying within the venous sleeve of pericardial reflection.It lies behind the left atriumPericardium separates the oblique sinus from esophagus.An oval shaped opening, between iVC and lower left pulmonary vein, directed downwards and to the left connect oblique sinus with the rest of the pericardial cavity.# It is bounded by:i) Anteriorlyii) Posteriorlyiii) Rightiv) Leftv) Above:- Left atrium:- Parietal layer:- Right pair of pulmonary veins and IVC:- Left pair of pulmonary veins:- Upper margin of left atriun.