What is the primary injection site commonly used for intramuscular injections in children aged 3 years?

The vastus lateralis is the primary injection site commonly used for intramuscular injections in children aged 3 years due to its size and the fact that it is well developed in younger children. This muscle, located on the outer thigh, is preferred because it is away from major blood vessels and nerves, which reduces the risk of complications during the injection.

In children, the vastus lateralis can accommodate larger volumes of medication compared to other sites, making it a safe and effective choice for administering vaccines and medications. Its accessibility and the fact that it is less likely to be affected by movement make it ideal for routine injections in this age group.

Other potential injection sites, such as the deltoid muscle, while appropriate for older children and adults, may not have sufficient muscle mass in very young children to handle intramuscular injections safely. The rectus femoris, another muscle in the thigh, is generally not preferred due to its proximity to the knee and potential for nerve injury. Similarly, the gluteus maximus, while a common muscle for injections in adults, is not advisable for young children because of the risk of injury to the sciatic nerve and the fact that it is not fully developed in early childhood.