What is the vastus lateralis?

The vastus lateralis is one of the four muscles that make up the quadriceps group, located on the outer side of the thigh. It is a preferred site for intramuscular injections in infants and small children primarily due to its size and accessibility; it's well developed even in young patients, allowing for safe administration of medications.

Using the vastus lateralis for injections minimizes complications, as it is away from major nerves and blood vessels compared to other injection sites. Additionally, this muscle is far less likely to be affected by medical conditions that might impact a thigh or arm injection site, making it a reliable choice for administering vaccines in this population.

While the vastus lateralis can also be used for vaccinations in adults, it is particularly emphasized for infants and small children because of their other muscle mass limitations and the need for a safe, effective injection site.