Abstract: The device includes a handpiece 1, its handle-shaped portion constituting an under pressure air receptacle 2. The handpiece 1 contains a pneumatic jack 15 fed by means of a pressure reducing valve 11 with constant air under pressure derived from the receptacle 2. The jack 15 pushes against a recall spring a catapult 16 bearing an injection needle 21. The piece 1 also bears a movable syringe 23 containing the liquid and connected to the needle 21 by a flexible pipe 22. A piston 29 moving in the syringe 23 is propelled by the air of a pressure chamber 35 fed from the receptacle 2 through a second pressure reducing valve 30. A squeezing piece 25 brings about a flattening of the pipe 22 by prohibiting the flowing of the liquid and it is pushed back at the outlet end of travel of the jack 15 so as to free the pipe 22 from squeezing.

Abstract: A tubular guard 14 encircles the needle 6 and exhibits a conical connection surface which, in the protection position, cooperates with a conical connection surface of the joining piece bearing the needle 6. By pushing on the cap 16 covering the needle 6, the joining piece and the associated guard are secured to the handpiece 1. The collar 17 is then pressed onto the guard 14 and frees the guard from the joining piece. The guard 14 is then hooked onto the handpiece 1 by freeing the end of the needle 6.