A medical gas distribution apparatus comprising at least a source of pressurised gas or of vacuum and at least a terminal unit for delivering a specific gas or for suction by means of vacuum, and a joint connecting said source and said terminal unit, wherein the terminal unit comprises an annular mouth, which extends around and along a first axis between a first and a second end (5, 7), and a plate oriented orthogonally to the first axis, having a through hole around the first axis, and fixed to the second end with the through hole surrounding the second end; said joint comprising: - a support element that internally defines a first duct extending along the first axis and that comprises a receiving portion and an interface plate (15, 28) fixing the same support element to the plate of said terminal unit with the interface plate (15, 28) extending orthogonally to the first axis in contact with the plate; and - a gas feeding element, which is carried by said support element, is housed within a housing defined by the receiving portion, is connected to said source, and internally defines a second duct in fluidic communication with said first duct and extending along a second axis transversal to said first axis; wherein said gas feeding element is orientable about said first axis with respect to said support element, wherein said interface plate (15, 28) comprises engagement means for coupling said support element to said terminal unit in one or more predetermined orientations with respect to said first axis, wherein the engagement means comprise a projection extending along the first axis, characterized in that the projection surrounds a hole extending through the interface plate (15, 28) and at least partially defining said housing. wherein the terminal unit comprises an annular mouth, which extends around and along a first axis between a first and a second end (5, 7), and a plate oriented orthogonally to the first axis, having a through hole around the first axis, and fixed to the second end with the through hole surrounding the second end; said joint comprising: - a support element that internally defines a first duct extending along the first axis and that comprises a receiving portion and an interface plate (15, 28) fixing the same support element to the plate of said terminal unit with the interface plate (15, 28) extending orthogonally to the first axis in contact with the plate; and - a gas feeding element, which is carried by said support element, is housed within a housing defined by the receiving portion, is connected to said source, and internally defines a second duct in fluidic communication with said first duct and extending along a second axis transversal to said first axis; - a support element that internally defines a first duct extending along the first axis and that comprises a receiving portion and an interface plate (15, 28) fixing the same support element to the plate of said terminal unit with the interface plate (15, 28) extending orthogonally to the first axis in contact with the plate; and - a gas feeding element, which is carried by said support element, is housed within a housing defined by the receiving portion, is connected to said source, and internally defines a second duct in fluidic communication with said first duct and extending along a second axis transversal to said first axis; wherein said gas feeding element is orientable about said first axis with respect to said support element, wherein said interface plate (15, 28) comprises engagement means for coupling said support element to said terminal unit in one or more predetermined orientations with respect to said first axis, wherein the engagement means comprise a projection extending along the first axis, characterized in that the projection surrounds a hole extending through the interface plate (15, 28) and at least partially defining said housing.