Abstract: A surgical instrument serves to insert a trocar needle into the bone marrow of a patient for connection of a syringe, an infusion set or the like. The instrument includes a cylindrical housing containing a sliding bolt and the trocar needle configured to be forcefully shot through the bone material into the marrow by release of a compressed helical spring. The bolt holds the rear end of the needle in a releasable grip permitting the needle to be released and to remain in the bone. The helical spring is positioned in the rear of the housing and of the bolt and is held in compressed state by a catch which is releasable by pressure on a trigger. This shoots the bolt and the needle forwards, a collar in the housing stopping the bolt sharply and allowing the needle to be released from the device after its penetration and to be connected to a syringe or an infusion set for intraosseous injection, infusion or other treatment.