The passage followed by magma in a volcano is called a conduit or vent.

* Conduit: This is the main channel through which magma rises from the magma chamber to the surface. It can be a single, vertical shaft or a more complex network of interconnected channels.

* Vent: This is the opening at the surface where the magma erupts. It can be a single, circular opening or a long, fissure-like crack.

So, the magma travels through the conduit and erupts through the vent, creating a volcanic eruption.