Expert Guide of Syringe/Needle Parts: Learn functions & diagram

The syringe is a simple reciprocating pump where the plunger acts as a piston that slides into the barrel. It helps to pull or push the medicine from or into the body. It consists of two main parts, Syringe and Needle. We can attach and detach the needle from the syringe through the needle hub. In all medical sectors, its use is typical and multipurpose. As it is used in the medical sector, the selection of plastic and metal plays an important role. In this article, we will see the parts of the syringe and needle and their functions.

Syringe Parts Diagram

Parts of Syringe and Needle, Names, Functions & Diagram

Parts of a Syringe

  • Plunger
  • Thumb Rest
  • Barrel
  • Luer Lock

Parts of a Needle

  • Needle Hub
  • Needle Shaft
  • Bevel
  • Protective Cover

Syringe Parts and Functions


In the Syringe, a plunger is a piston that is pressed into the barrel to force liquid through the needle. With the help of a plunger, we can pull and push liquid medicine into the barrel. 

Thumb Rest

It is the end portion of the plunger. It is flat in shape. We can rest our thumbs on it while expelling the liquid. On the other end of the plunger, a rubber cap is there to avoid leakage and air-tight sealing. 

Generally, the material of the plunger is plastic or colored glass.


A barrel is a cylindrical part of the syringe in which liquid medicine or blood can be pulled or pushed. 

The barrel has a calibration scale to measure the quantity of medicine or blood to give or remove from the body of the patient.

Luer Lock

This Luer lock is the end connection of the syringe. It has a screw structure that allows the needle to get fit with the syringe. 

There are three Luer lock connections there. Luer Lock Tip, Luer Slip Centric Tip, Luer Slip Eccentric Tip.

Parts of a Syringe Needle and Functions

Needle Hub

It is an adapter that holds the needle and the other ends get to connect with a syringe. It locks the needle with the syringe while pulling and pushing the liquid medicine into the body.

Needle Shaft

A needle shaft is a steel needle that is fixed in the needle hub. It is hollow from the inside to pass liquid medicine from it.

Needle Bevel

A needle bevel is a cut at the end of the needle. It has a sharp edge that helps to insert the needle into the body of any animal.

Needle Protective Cover

It is a protective cover to protect the needle from any dust particles that enter it. It is so simple to cover and remove the cap from the needle.

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