7 protrudes or extends through the puncture needle attachment 6 the connection chamber 5 a cannula head 13 and through the cannula 2 in fig1 a the cannula 2 and the puncture needle 7 situated therein are still enclosed by a protective sheath 2 a which is removed before use a connector 11 which is linearly displaceable in the direction of a movement axis l is designed as a hollow body in this embodiment its cavity forms a fluid channel 4 that extends in the direction of the movement axis l of the connector 11 the l axis extends at least substantially parallel to an underside of the catheter head housing 3 that rests on the skin during use the connector 11 in fig1 a is located in its first position so that the puncture needle 7 can be guided from the puncture needle attachment 6 into the connection chamber 5 and from there onward into the cannula 2 without touching or passing through the connector 11 the connector 11 has a passage 8 at one place on its jacket enclosing the fluid channel 4 at least around this passage 8 the connector 11 firmly rests against the catheter head housing 3 in this embodiment the whole connector 11 is made of a soft material the side faces of the connector 11 are.