Assertion: hamstring | /r/CapableOf | flex the knee
Facets:
Source sentences:
text: Because they cross the hip and the knee, the hamstrings function primarily to flex the knee and extend the hip.
text: This landing mechanism does not allow the hamstrings to flex and protect the knee.
text: The hamstrings are the powerful posterior thigh muscles that extend the hip and flex the knee.
text: The hamstrings flex the knee, while the quadriceps extend it.