Other half of muscles acting on the knee + leg

sartorius origin

Anterior superior iliac spine

sartorius insertion

Medial surface of tibia just inferomedial to tibial tuberosity

sartorius innervation

Femoral nerve (L2, L3)

sartorius action

Flexes the thigh at the hip joint

flexes the leg at the knee joint

biceps femoris origin

Long head—inferomedial part of the upper area of the ischial tuberosity;

short head—lateral lip of linea aspera

biceps femoris insertion

Head of fibula

biceps femoris innervation

Sciatic nerve (L5, S1, S2)

biceps femoris action

Flexes leg at knee joint;

extends and laterally rotates thigh at hip joint

laterally rotates leg at knee joint

semitendinosus origin

Inferomedial part of the upper area of the ischial tuberosity

semitendinosus insertion

Medial surface of proximal tibia

semitendinosus innervation

Sciatic nerve (L5, S1, S2)

semitendinosus action

Flexes leg at knee joint

extends thigh at hip joint;

medially rotates thigh at hip joint and leg at knee joint

semimembranosus origin

Superolateral impression on the ischial tuberosity

semimembranosus insertion

Groove and adjacent bone on medial and posterior surface of medial tibial condyle

semimembranosus innervation

Sciatic nerve (L5, S1, S2)

semimembranosus action

Flexes leg at knee joint

extends thigh at hip joint;

medially rotates thigh at hip joint and leg at knee joint

(same as semitendinosus?)

popliteus origin

Lateral femoral condyle

popliteus insertion

Posterior surface of proximal tibia

popliteus innervation

Tibial nerve (L4 to S1)

popliteus action

Stabilizes knee joint (resists lateral rotation of tibia on femur)

Unlocks knee joint (laterally rotates femur on fixed tibia)