| Muscles Acting On The Knee |
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Origin |
Insertion |
Innervation |
Action |
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| ANTERIOR: |
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| Vastus Medialis |
Medial part of intertrochanteric line, pectineal line, medial lip of the linea aspera & medial supracondylar line of the femur |
Quadriceps tendon |
Femoral nerve (L2 – L4) |
Extension of the knee |
| Vastus Intermedialis |
Upper 2/3 of anterior & lateral surfaces of the femur |
Quadriceps tendon |
Femoral nerve (L2 – L4) |
Extension of the knee |
| Vastus Lateralis |
Lateral part of intertrochanteric line, margin of greater trochanter, lateral margin of gluteal tuberosity & lateral lip of the linea aspera of the femur |
Quadriceps tendon |
Femoral nerve (L2 – L4) |
Extension of the knee |
| Rectus Femoris |
One head originates from the anterior inferior iliac spine; one head originates from the ilium just superior to the acetabulum |
Quadriceps tendon |
Femoral nerve (L2 – L4) |
Flexes the hip joint & Extension of the knee |
| Sartorius |
Anterior superior iliac spine |
Anterior surface of tibia just inferomedial to tibial tuberosity |
Femoral nerve (L2 – L3) |
Flexes the hip joint & flexes the knee |
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| MEDIAL: |
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| Gracilis |
External surface of the pubis, the inferior pubic ramus & the ramus of the ischium |
Medial surface of proximal shaft of tibia |
Obturator nerve (L2 – L3) |
Adducts the hip joint & flexes the knee joint |
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| POSTERIOR: |
| Biceps Femoris |
Long head: inferomedial part of the upper area of the ischial tuberosity |
Head of fibula |
Sciatic nerve (L5 – S2) |
Flexes the knee joint, extends & laterally rotates the hip joint & laterally rotates the knee joint |
| Short head: Lateral lip of linea aspera |
| Semitendinosus |
Inferomedial part of the upper area of the ischial tuberosity |
Medial surface of proximal tibia |
Sciatic nerve (L5 – S2) |
Flexes the knee, extends the hip, medially rotates the hip joint & knee joint |
| Semimembranosus |
Superolateral part of the ischial tuberosity |
Groove & adjacent bone on medial & posterior surface of medial tibial condyle |
Sciatic nerve (L5 – S2) |
Flexes the knee, extends the hip, medially rotates the hip joint & knee joint |
| Gastrocnemius |
Medial head: posterior surface of distal femur on medial condyle |
Via calcaneal tendon to posterior surface of calcaneus |
Tibial nerve (S1 – S2) |
Plantar flexion of the ankle & flexion of the knee |
| Lateral head: upper posterolateral surface of lateral femoral condyle |
| Plantaris |
Inferior part of lateral supracondylar line of femur & oblique popliteal ligament of the knee |
Via calcaneal tendon to posterior surface of calcaneus |
Tibial nerve (S1 – S2) |
Plantar flexion of the ankle & flexion of the knee |
| Popliteus |
Posterior surface of proximal tibia |
Lateral femoral condyle |
Tibial nerve (L4 – S1) |
Laterally rotates femur onto fixed tibia (unlocks the knee) |
