The Quadriceps.
hamstrings
The Gastrocnemius and the Soleus flexes the knee and the foot. The Plantaris is an unimportant muscle. Many people do not have it and doctors tend to use this muscle for tendon graphs.
hamstring group is the primary muscle group for flexing the knee
The flexor would be the hamstring, and gastrocnemius, which bend/flex the knee. The quadriceps, are extensors, which straighten/extend the knee.
The primary muscle responsible for extending the thigh is the quadriceps femoris, specifically the rectus femoris. To flex the knee, the primary muscles involved are the hamstrings, particularly the biceps femoris, semitendinosus, and semimembranosus. These muscle actions are important for movements like running and kicking.
The plantaris is the smallest muscle in the human leg. It is used to flex the knee joint and is absent in about 7 percent of the human population.
Paralysis of the quadriceps femoris muscle would make an individual unable to flex the thigh. This muscle is responsible for extending the knee and flexing the thigh at the hip joint.
To extend the leg straight at the knee you use the quadriceps. To bend the knee, you need the hamstring.Hamstring muscle groups.
A muscle that, from origin to insertion, crosses two joints, and thus can produce an action at both joints. Example: the "hamstrings" (semimembranosis and semintendinosis) cross the hip joint and the knee joint and act on both joints (extend at hip, flex at knee).
The muscle of the thigh are classified into three groups, anterior group, posterior group, and interior or adductors group. There are four muscle on the anterior group - quadriceps femoris- and their function is to extend the knee or extend the thigh depend on what part of the muscle don't move. Those muscle are the rectus femorarlis, vastu intermedius, vastu medialis, and vastus lateralis. The muscle that flex the knee are located on the back of the thigh and form the posterior group. They are the biceps femoris, semitendinousus, and the semimembranosus, better known as Hamstring.
The primary antagonist to the rectus femoris is the biceps femoris, a muscle of the hamstring group. When the rectus femoris contracts to flex the hip and extend the knee, the biceps femoris acts to flex the knee and extend the hip, helping to create balanced movement.
Yes. from behind. (They flex the knee.)