<Table> <Tr> <Th_colspan="2"> Superior vena cava </Th> </Tr> <Tr> <Td_colspan="2"> Veins </Td> </Tr> <Tr> <Th_colspan="2"> Details </Th> </Tr> <Tr> <Th> Precursor </Th> <Td> common cardinal veins </Td> </Tr> <Tr> <Th> Source </Th> <Td> brachiocephalic vein, azygos vein </Td> </Tr> <Tr> <Th_colspan="2"> Identifiers </Th> </Tr> <Tr> <Th> Latin </Th> <Td> vena cava superior, vena maxima </Td> </Tr> <Tr> <Th> MeSH </Th> <Td> D014683 </Td> </Tr> <Tr> <Th> TA </Th> <Td> A12. 3.03. 001 </Td> </Tr> <Tr> <Th> FMA </Th> <Td> 4720 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Superior vena cava </Th> </Tr>

Where does the blood from the superior vena cava come from