MUSCLES:

FLEXORS:
Hamstrings (semi membranosus, semiteninosus, biceps femoris)
gastrocnemius
popliteus

EXTENSORS:
vastus medialis
vastus lateralis
vastus intermedius
rectus femoris

LIGAMENTS:
medial and lateral collateral
anterior and posterior cruciate
infrapatellar
coronary

COMMENTS: The main movements of the knee are flexion and extension. For lateral knee pain, look at the vastus lateralis. For anterior knee pain, see the vastus medialis. For posterior knee pain, see all the flexors.