Which part of a syringe indicates the volume of fluid inside?

The barrel of a syringe is the part that indicates the volume of fluid inside. It is typically marked with measurement markings (often in milliliters) that allow the user to read exactly how much fluid is contained within it. This is crucial for accurate administration of medications, as healthcare providers need to determine the precise dosage required for patient care.

The plunger, while essential for drawing up or expelling the fluid, does not indicate volume itself; it simply moves within the barrel. The shaft is not a term commonly used in reference to the parts of a syringe in this context and might cause confusion. The needle, which is the sharp metal component used for injection, does not provide any volume measurement. Therefore, the barrel stands out as the correct answer for identifying the volume of fluid in a syringe.