Final answer:
The vastus lateralis injection site is located on the lateral aspect of the thigh and is preferable for intramuscular injections. It lies lateral to the anterior superior iliac spine and is found in the outer middle third of the thigh.
Step-by-step explanation:
The vastus lateralis injection site is a preferred location for intramuscular injections due to its thick muscle mass and minimal nerve distribution. This muscle is one of the quadriceps muscles located on the lateral aspect of the thigh, which is the outer part of the thigh. To locate the vastus lateralis injection site, divide the thigh into three equal parts vertically and horizontally. The injection site is located in the outer middle third. This area is bounded superiorly by the greater trochanter of the femur and inferiorly by the lateral femoral condyle.
An important landmark for locating the vastus lateralis injection site involves the anterior superior iliac spine which is a bony prominence you can feel at your anterolateral hip. The vastus lateralis muscle and the injection site are situated lateral and somewhat inferior to this bony landmark. When administering an injection into this muscle, care should be taken to avoid the other surrounding muscles, such as the vastus intermedius which lies between the vastus lateralis and vastus medialis and deep to the rectus femoris and the vastus medialis which is the muscle on the medial aspect of the thigh.