Through the ribs.
A chest tube
is inserted by making a small incision
on the side of the chest, usually along the same level as the nipple, and bluntly penetrating into the chest cavity
over one of the ribs.
This is done using a blunt instrument. Once the tract into the chest is created, the tube is inserted and tied in place. It is then attached to a canister that will drain the fluid or air from the chest cavity.