The anatomy of the syringe

1. Stopper

Prevents leakage of medication around the plunger, and acts as an indicator for measuring the syringe’s contents (see diagram).

2. Scale Markings

Scale markings are typically in milliliter (mL) units. On insulin syringes, however, graduations are displayed in “units” based on the insulin concentration prescribed. (Example: U-100 means 100 units of insulin suspended within 1 milliliter of fluid. A 3/10 mL insulin syringe will accommodate up to 30 units when using U-100 insulin.)

3. Barrel

Reservoir for holding liquid, clearly graduated to allow accurate and visual measurement of the syringe’s contents.

4. Flanges

The “wings” that extend out from the side of the syringe barrel that provide an area or surface for the index finger and middle finger to grasp during aspiration or administration.

5. Plunger Rod

A piston-like device inside the barrel.

6. Thumb Press

Area where clinician presses to push plunger rod down into barrel to expel contents.

	Luer Lock Tip	Generally used for injections requiring a secure connection of the syringe to another device. The tip is threaded for a “locking” fit, and is compatible with a variety of needles, catheters and other devices.
	Luer Slip Tip	A friction-fit connection that requires the clinician to insert the tip of the syringe into the needle hub of other luer connection in a push-and-twist manner. This will ensure a connection that is less likely to detach. Simply sliding the attachment device onto the syringe tip may not ensure a secure fitting.
	Eccentric Luer Slip Tip	Allows for work requiring closer proximity to the skin. Generally used for venipunctures and aspiration of fluids. (Also see luer slip instructions above.)
	Catheter Tip	Used for flushing (cleaning) catheters, gastrostomy tubes and other devices. Insert catheter tip securely into catheter or gastrostomy tube. If leakage occurs, refer to your facility’s guidelines.
	Permanently Attached Needle	Most commonly found in insulin and ‘tuberculin’ syringes. Permanently attached needles, also known as integral needles, reduce the ammount of medication waste and allow accurate mixing of different medications into one syringe.