Deltoid Injection for Vaccination
The deltoid intramuscular injection (IM) is a common procedure. One must be aware of the proper location for the injection and the proximity of the neurovascular structures present within the involved region. Despite the deltoid being an ideal location for vaccination administration, the size of the deltoid mass is small in relationship to other IM injection sites which leaves little margin for error when administering the injection. Thus, accurate identification of the safe zone for injection is important. The correct location for the injection is in the middle part of the deltoid muscle from the sagittal view. The acromion process is a great landmark to help in selecting the proper site for injection. Identify the acromion and go about 2.5 to 5cm (1-2 inches) distally to the muscle belly of the deltoid. When administering the injection, you can use the square method or the triangle method, both of which are effective. If you superimpose both injection techniques, the ideal site for injection remains about the same. Some people may make a triangle with the fingers as shown here in order to have a proper location for the injection. You can see that the top finger is over the acromion process. Inferiorly, there is less of a safe zone due to the close proximity of the neurovascular bundle to the inferior part of the deltoid. Care must be given not to cause injury to the axillary nerve or the radial nerve during injection into the deltoid muscle. The axillary nerve runs transversely from posterior to anterior about 7cm distal to the acromion. The injection site should not exceed 5cm distal to the acromion in order to avoid inuring the axillary nerve.
