The invention relates to a gas filling and distribution head (2) which is intended to be disposed in a hole in a pressurized gas storage tank. The inventive head (2) includes a mounting segment (21) which is intended to be housed in the hole in the tank and an expansion segment which houses a pre-expansion device (22), said pre-expansion device (22) being arranged in relation to the mounting segment (21) such as to be housed at least partially inside the tank when the head is in the mounted position. The head (2) also includes: a filling circuit which extends between a first end which is equipped with a filling hole (6) and a second end which is intended to communicate with the interior of the tank, and an extraction circuit which extends between a first end which is intended to communicate with the interior of the tank and a second end which is equipped with an extraction hole. The invention is characterized in that the filling hole (6) is aligned with the extraction hole.