Question

drugs are commonly injected into tissues rather than directly into the bloodstream. this method makes it possible to introduce a large amount of a drug at one treatment, yet have it enter the circulation gradually. an intramuscular (im) injection introduces the drug into the mass of a large skeletal muscle. bulky muscles, like the gluteus maximus and deltoid muscles that contain few large vessels or nerves make ideal injection sites. the vastus lateralis muscle is another common injection site. the vastus lateralis belongs to the quadriceps group.
what is the principle action of the vastus lateralis and the other quadriceps muscles?
extension and lateral rotation at hip
flexion of the knee
flexion of the hip
extension of the knee

Explanation:

The quadriceps muscle group, including the vastus lateralis, is located on the anterior thigh. Its primary function is to straighten the knee joint, which is knee extension. Knee flexion is controlled by posterior thigh muscles like the hamstrings, while hip flexion/extension/rotation are handled by other muscle groups.

Answer:

extension of the knee