Vastus lateralis is a muscle located on the front and outer side of the thigh. This muscle is also known as the outer vastus muscle or vastus externus muscle. Within the muscle group of the quadriceps femoris, the vastus lateralis muscle is responsible for extending and straightening the knee. Other synonyms for this muscle include the lateral vastus muscle, vastus externus lateralis, and vastus externus muscle. Understanding the different synonyms for the vastus lateralis muscle can help in communication between healthcare professionals and individuals experiencing knee or thigh-related issues. Overall, this muscle is essential for a range of movements we make in our daily lives.