Final answer:
The rectus femoris injection site for intramuscular injections is found in the middle third of the line drawn from the anterior superior iliac spine to the greater trochanter of the femur, in the anterior aspect of the thigh.
Step-by-step explanation:
The rectus femoris injection site in intramuscular injections is located in the anterior aspect of the thigh. Identifying the correct location involves palpating important bony landmarks such as the anterior superior iliac spine and the greater trochanter of the femur. For the injection, you would typically divide the distance between these two landmarks into thirds. The injection is administered in the middle third, which is generally safe from the structures like the sciatic nerve and femoral artery. The vastus lateralis, which is the muscle on the lateral aspect of the thigh, is also often used for intramuscular injections, especially in children and infants, due to its ample muscle mass.