Both
The quadriceps femoris group extends the leg at the knee joint. It is responsible for straightening the knee and kicking movements.
The pair of antagonistic muscles used in kicking a ball are the quadriceps (agonist) and hamstrings (antagonist). The quadriceps contract to extend the knee and straighten the leg to generate power for the kick, while the hamstrings act to flex the knee and control the movement.
The knee helps your leg flex and extend.
The hamstrings flex the knee and extend the hip.
Crepitus is the grinding sensation that can be felt if you place your hand over the knee and flex and extend it.
Biceps Femoris, Semimembranosus, and Semitendinosus
no. flexing is deceasing the angle (e.g bending knee) extending is straightening something. (e.g. straightening knee)
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.
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.
Muscles that flex the knee are the hamstrings which include your semitendinosus, semimembranosus and biceps femoris musces. Muscles that extend the knee are the quadriceps muscles which includes your vastus lateralis obliques, vastus intermedius, vastus medialis obliques and your rectus femoris.
Quadriceps contracts to extend the knee joint. Rectus femoris, the part of quadriceps flex the hip joint on the thigh.
The flexor would be the hamstring, and gastrocnemius, which bend/flex the knee. The quadriceps, are extensors, which straighten/extend the knee.