thumb|Depiction of the heart, major veins and arteries constructed from body scans Oxygenated blood enters the systemic circulation when leaving the left ventricle, via the aortic semilunar valve. The first part of the systemic circulation is the aorta, a massive and thick-walled artery. The aorta arches and gives branches supplying the upper part of the body after passing through the aortic opening of the diaphragm at the level of thoracic ten vertebra, it enters the abdomen. Later, it descends down and supplies branches to abdomen, pelvis, perineum and the lower limbs.
thUmB|DePIctioN Of the HearT, MAJor veinS AND arTeries ConstrUctEd frOM boDy scaNS OxYGeNateD Blood enteRs thE SysteMic cirCulatION when leaviNG tHE Left vEntRiClE, via The aortiC semiluNaR VALve. thE fIrSt paRt of thE sYstemic cirCulATIon Is thE aorTA, a massIvE and thick-waLLed artery. ThE aorta ArChEs And givEs branChes sUpplYIng tHe upper pArT of THe boDy AFter passing THrough tHe aOrTic OpeninG oF the diaPHRagm aT thE leVeL of thoraciC teN VerteBra, it eNters THE aBdomen. laTer, iT DesCeNdS dOwN anD SupPliEs branches To abDOmen, pelvIs, PErIneum anD tHe LoweR limbS.