Structure and Function: The Quadriceps
The top of the thighs are made up of a pretty large muscle group known as the quadriceps, which are four muscles used to stabilize and extend the leg. Three of these (the Vastus Lateralis, Vastus Medialis and Vastus Intermedius) begin below the hip, on the femur and attach to the kneecap. The other, Rectus Femoris, overlaps the other three, crossing the hip and also attaching to the knee
The knee is the largest joint in the human body. It connects the Tibia and Fibula of the lower leg to the Femur of the upper leg allowing for flexion and extension of the leg. This makes it such an integral, structural component of the human body.

Let’s begin at the top. The Rectus Femoris attaches on the hip and plays a role in hip flexion (pulling the legs toward the abdomen) and knee extension. All of the Vastus muscles work to extend the leg to provide movement whenever standing up or running. The Vastus Lateralis is the largest lying on the outside of the thigh. The Vastus Intermedius inserts right above the knee and travels up the center of the leg, ending at the Rectus Femoris. The Vastus Medialis (VMO) is on the inside of the leg and is activated when the leg is fully lengthened.
Performing leg extensions to a certain degree in order to engage the entire group of muscles is not an easy task for everyone. Different things can affect the mobility of your knee such as tight hamstrings or a weak Vastus Medialis, but both can be improved.
Now you can go hit leg day with a little more confidence using leg extensions, leg press, squats and lunges to isolate the Quadriceps.
About the author
Dwayne Wimmer founded Vertex Fitness Personal Training Studio in 2001, excited to bring a new concept about personal training to the people of Philadelphia’s Main Line in Pennsylvania. Driven by knowledge and results both, while a strength coach at Villanova University, he worked closely with world class athletes such as Brian Westbrook, formerly of the Philadelphia Eagles, on strength training and conditioning for optimal performance. Dwayne’s client base extends much further than world class athletes. Along with athletes, he works with adolescents to seniors, and he’s a highly acclaimed and sought out personal trainer who has received numerous awards, such as Best of the Main Line Personal Training Studio and Best Main Line Personal Trainer.
A graduate of Missouri Western State University, Dwayne has a Bachelor of Science degree in Physical Education, with an emphasis in Coaching. Aside from personal training, he’s spent time as a physical education teacher, strength and conditioning coach, and a football coach, but has found his passion and home in the fitness industry, inspiring and reaching out to others. As a strong believer in continuing to learn, Dwayne has also taken classes at East Stroudsburg University toward a Masters Degree in Sports Management.
He can add author to his list of accomplishments, having created a chapter in the upcoming book The Soul of Success with Jack Canfield, renowned for the Chicken Soup series.
To get to the point where he is now, Dwayne has always been thankful for the support of his father, a man who always believed in his mission and saw the need for what it was that Dwayne envisioned. During his free time, Dwayne is an avid motorcyclist who enjoys viewing the amazing landscapes and finding good restaurants to enjoy that are off the beaten path. He also takes advantage of opportunities to travel and experience many other cities while attending fitness seminars and giving presentations about the industry he is so passionate about. As a way to give back to the community that has been a part of his entire life, Dwayne has created Vertex Fitness PUMPED (People United Making Progress through Education and Donations), which provides support to area non-profits through a community-wide outreach effort. At this time, they help three non-profits per year in the Philadelphia area.
For more information from Dwayne, you may contact him at (610) 525-6604, dwayne@vertexfit.com