Nursing Acceleration Challenge Exam (NACE) PN-RN Practice Test

At what angle should an intramuscular injection be administered in the deltoid muscle?

1. 90°

2. 60°

3. 45°

4. 30°

The correct answer is: 90°

An intramuscular injection in the deltoid muscle should be administered at a 90-degree angle. This angle is appropriate because it allows the needle to penetrate directly into the muscle tissue, ensuring that the medication is deposited within the muscle rather than in subcutaneous tissue. Injecting at a 90-degree angle maximizes the depth of the injection, which is crucial for medications that require muscle absorption to achieve the desired therapeutic effects. The deltoid muscle is relatively shallow compared to other sites used for intramuscular injections, and a perpendicular approach helps to reach the muscle effectively while minimizing the risk of injury to nerves or blood vessels nearby. Administering the injection at lesser angles—such as 60 degrees, 45 degrees, or 30 degrees—would not facilitate the same depth of injection, potentially leading to ineffective medication delivery and increased chances of complications. Thus, the 90-degree angle is the standard practice for this type of intramuscular injection.