They are the Vastus Medialis, Intermedius and Lateralis and finally the Rectus Femoris.
The Quadriceps attach to the front of the tibia and originate at the top of the femur.
The exception to this rule is the Rectus Femoris which actually crosses the hip joint and originates on the pelvis.
The function of the Quadriceps as a whole is to extend the knee (straighten the knee).
The Rectus Femoris functions to extend the knee but also acts as a hip flexor because it crosses the hip joint.
Anatomy and Exercises
Find out what functions your muscles perform and how they work
Learn what your muscles look like inside you and where they are in your body
When the knee joint is affected by arthritis, the muscles of the front of the thigh, which straighten and control the knee (known as the quadriceps) often become wasted and weak. This means that the knee joint is not supported as it should be and can become unstable, sometimes giving way.
Regular quadriceps exercises will maintain, and even improve, the muscle strength. This can improve knee function, reducing pain and swelling, and making the knee joint more stable.
You should lie or sit comfortably on a firm surface, such as the floor or a firm bed, with your legs stretched out straight. Tense the muscles around the knee, as if pushing the knee down onto the firm surface. Try and use all the muscles of the leg so that the foot is drawn up and the knee is completely flat. You should keep the muscles of the leg tense for at least ten seconds. This is called sustained contraction and makes the exercise more effective.
A more testing form of quadriceps exercise is that similar to those used for practising prior to going skiing. The person stands with knees bent to a near right angle, with the back flat against a secure wall. That position is held as long as possible in the face of sometimes considerable discomfort! This is a very effective way, without using...
Maintain your ideal body weight. The more you weigh, the more stress you are putting on your joints, especially your hips, knees, back and feet.
Move your body. Exercise protects joints by strengthening the muscles around them. Strong muscles keep your joints from rubbing against one another, wearing down cartilage. We can help you get started on an exercise program that works for you.
Stand up straight. Good posture protects the joints in your neck, back, hips and knees.
Pace yourself. Alternate periods of heavy activity with periods of rest. Repetitive stress on joints for long periods of time can accelerate the wear and tear that causes osteoarthritis.
Listen to your body. If you are in pain, don't ignore it. Pain after activity or exercise can be an indication that you have overstressed your joints.
Don't be static. Changing positions regularly will decrease the stiffness in your muscles and joints.
Forget the weekend warrior. Don't engage in activities your body for which your body isn't prepared. Start new activities slowly and safely until you know how your body will react to them. This will reduce the chance of injury.
Wear proper safety equipment. Don't leave helmets and wrist pads at home. Make sure you get safety gear that is comfortable and fits appropriately.
Ask for help. Don't try to do a job that is too big for you to handle. Get another pair of hands to help out.