The syringe is the injection device that medication is drawn into. IM injections can range from one milliliter to four milliliters in volume, which can be measured in the barrel of the syringe. The size of the muscle determines the maximum amount of medication it can receive. Large muscles, such as the dorsogluteal and ventrogluteal, can receive up to four milliliters. The plunger is the part of the syringe that pushes medication through the needle when pressed. To prevent accidental sticks, the needle cap covers the needle before administration.
The deltoid site
The ease of access, especially in an outpatient setting, possibly adds to the frequency with which the deltoid site is used for IM injections. This site is used for immunisations/non-irritating medications, hence vaccines which are usually small in volume tend to be administered into the deltoid site. 9 This is a relatively small area and muscle mass, especially in atrophied patients compounded by the close proximity of the radial nerve, brachial artery and bony processes to this site means that more substantial injuries can occur.