What is the term for the hollow inside of a needle?

The term for the hollow inside of a needle is "lumen." The lumen refers to the inner space or cavity of the needle that allows fluids to flow through. This is essential for the functioning of the needle, as it enables the delivery of medications or the drawing of blood. Understanding this terminology is vital for medical professionals, as it directly relates to the administration of injections and venipuncture procedures.

The other terms mentioned are important components of a syringe system, but they refer to different parts. The bevel is the angled tip of the needle that allows for smoother penetration into the skin. The syringe is the device that holds the fluid to be injected or drawn, and the barrel is the part of the syringe where the fluid is housed and scaled for measurement. Each of these components plays a critical role in surgical and medical procedures, but they do not refer specifically to the hollow section of the needle itself.