Injection syringe

A syringe provided with a body, a piston capable of sliding in the body, and an injection device comprising a needle oriented along a longitudinal axis and a casing removably secured to the body and carrying said needle, the casing comprising a plurality of flexible tabs each provided with a stop, the piston comprising a docking system provided with a housing that comprises a flange configured to hold the stops of the flexible tabs in the housing in an insertion position in which the tabs are inserted into the housing, the plurality of tabs comprising a first tab and a second tab situated in opposing areas around the longitudinal axis, the flange comprising a first bearing area and a second bearing area configured to be in contact with the first tab and the second tab respectively in the insertion position, wherein the first tab and the second tab are configured to provide elastic support respectively on the first bearing area and the second bearing area in the insertion position, and in that the first bearing area and the second bearing area are dissymmetrical relative to the longitudinal axis, wherein a bearing surface of the first bearing area and a bearing surface of the second bearing area extends toward each other at a same height level along the longitudinal axis, and wherein the first bearing area defines a top surface and a bottom surface having a first bearing area height defined there between and the second bearing area defines a top surface and a bottom surface having a second bearing area height defined there between and the first bearing area height and the second bearing area height are the same.