Superior vena cava
The superior vena cava was a  in the humanoid body.

In 2151, while being quizzed on Human anatomy by Doctor Phlox, Cutler identified the external jugular as being connected to the superior vena cava, which in turn was connected to the heart. ()

In 2369, in "Takaran Anatomy" for Doctor Jo'Bril, the superior vena cava was listed under lateral sternal in the graphic. ()

External link

Anatomy