A prefilled medical syringe includes a syringe barrel. A syringe plunger is disposed in the barrel and displaceable by means of a plunger rod. An end plug closes off a cannula side of the syringe barrel. The plug is provided with a through-channel closed off by a membrane. A finger support is disposed at the end of the syringe barrel opposite the end plug and provided with a through-opening for the plunger rod. A thread system cooperates with the plunger rod and the finger support. The thread system includes a thread sleeve detachably connected with the finger support. The thread sleeve is provided with an inner thread that cooperates with an outer thread on the plunger rod.