A hypodermic syringe comprises a barrel, a plunger slidably received in the barrel, a drive shaft slidable in the barrel, and a connector for drivably connecting the drive shaft to the plunger. The connector has a plunger end including a first pair of resilient fingers insertable into the plunger, a drive shaft end having second pair of fingers insertable into the drive shaft, and an intermediate portion intermediate the plunger and drive shaft ends. The first pair of fingers has projections which engage apertures in the plunger. The second pair of fingers engages an annular rib in the drive shaft. When the drive shaft is fully inserted into the barrel to bottom the plunger, the drive shaft slides over the first pair of fingers, causing the fingers to retract and the projections to disengage from the apertures in the plunger. The connector remains engaged with the drive shaft, and separates from the plunger the drive shaft is withdrawn from the barrel, thereby preventing further use of the syringe.

A syringe comprising a barrel having a needle extending from a needle end of the barrel, a plunger and a protective sleeve. There is a groove in the inner surface of the sleeve and a key extending from the outer surface of the barrel into the groove. The groove has a longitudinal section and a circumferential section. The circumferential section has opposing and offset zig-zag edges. A spring biases the barrel toward the protective sleeve. By pressing the plunger against the force of the spring, the key moves in the groove, sliding along the zig-zag edges. The design of the groove cooperates with the operation of the syringe and can cause the key to move into the longitudinal groove and the needle to thereby retract into the protective sleeve after the plunger is depressed.

An instrument for directing the insertion of a penetration member urged through tissue. The instrument includes a shaft, and a backstop positioned at a distal end of the shaft. The backstop and shaft are configured such that the backstop may be positioned adjacent one side of the tissue to be penetrated, and a penetration member may thereafter be urged through the opposite side of the tissue into the backstop. A method of penetrating the tissue wall of an anatomical cavity is also provided.

An instrument for the penetration of tissue, including a backstop assembly having a shaft and a backstop; and a penetration member slidingly engaged with the backstop shaft, and configured for penetrating tissue. The backstop assembly and the penetration member are configured such that the backstop may be positioned adjacent tissue to be penetrated, such that as the penetration member is urged through the tissue along the backstop shaft, the backstop will limit the depth of penetration of the penetration member through the tissue. A method of using this instrument is also provided.

A trocar employing an internal stabilizer and an optional external stabilizer is provided. The internal stabilizer is passed through the tissue wall along with the cannula, with the internal stabilizer in a retracted position. Once the cannula has been extended into the anatomical cavity, the stabilizer returns to its normal, extended position. Movement of the stabilizer between its retracted and extended positions is effected by advancement and retraction of the obturator. A method of inserting the trocar cannula is also provided.