The quadriceps muscle helps straighten and extend the leg and the hamstring helps bend the knee.
Quadriceps femoris
LCL
The only muscle of the leg that is made up of three muscles are the hamstrings.
The type of muscle that bends a joint is called a flexor muscle. Flexor muscles contract to decrease the angle between two bones at a joint, facilitating movements like bending the elbow or knee. These muscles work in opposition to extensor muscles, which increase the angle at a joint.
Hamstrings ( Biceps Femoris, Semitendinosus & Semimembranosus) are the Agonistic Muscles Quadricpes ( Rectus Femoris, Vastus Lateralis, Vastus Medialis & Vastus Intermedius) are the Antagonistic Muscles Hope I Helped... Sharnie x :)
knee
Deep knee bends.
knee bends
The Gastrocnemius. There is another muscle involved in plantar flexion. The soleus and the tibialus posterior maintains the arch. The only one that does both actions, though, is the Gastrocnemius.
Spine. Bone, not muscle.
flexion of the knee.
A flexor muscle.