THE KNEE JOINT Muscles That Act On The Knee Muscles of the Knee Joint Hamstrings All - flexion Quadriceps All - extension Unclassified Sartorius - flexion and internal rotation Gracilis - flexion and internal rotation Popliteus - flexion (unlocking) and internal rotation Gastrocnemius - flexion Anterior Muscles Quadriceps knee extension Vastus medialis Origin: Medial lip of the linea aspera Insertion: Inner half of the quadriceps tendon then the tibial tuberosity via the patellar tendon Action: Extension of the knee Rectus femoris Two joint muscle; most superficial Origin: anterior-inferior iliac spine of the ilium Insertion: top of the patella and patellar ligament to the tibial tuberosity Actions: Extension of the knee Vastus lateralis Origin: Lateral lip of linea aspera. Insertion: The lateral quadriceps tendon then the tibial tuberosity via the patellar tendon Action: Extension of the knee Vastus intermedius Origin: Upper 2/3 of the anterior surface of the femur Insertion: Upper border of the quadriceps tendon then the tibial tuberosity via the patellar tendon Action: Extension of the knee Quadriceps Muscles VLRFVM Quadriceps Hamstrings Vastus Lateralis Vastus Intermedius Rectus Femoris Vastus Medialis QUADRICEPS MUSCLES Vertical jumping Decelerating or eccentric contraction during landing or changing directions As a group, they are typically 25-30% stronger than the hamstrings Posterior Knee Muscles Hamstrings knee flexion Biceps femoris Lateral side Origin: 1.) Long head - ischial tuberosity; 2.) Short head - lower half of the linea aspera Insertion: Head of the fibula Action: Flexion of knee Semitendinosus Medial side; superficial Origin: Ischial tuberosity Insertion: Anterior medial surface of the tibia Action: Flexion of the knee Semimembranosus Medial side, deeper than semitendonosus Origin: Ischial tuberosity Insertion: Anterior medial surface of the tibia Action: Flexion of the knee HAMSTRING MUSCLES More knee flexors than hip extenders Acceleration muscles during running Tight hamstring muscles can contribute to lower back, hip and knee problems Gracilis O: Pubis crest I: Anterior medial surface of the (Pes anserine Tendon) Actions: flexion at the knee Sartorius Posterior at the knee joint Origin: Anterior-superior spine of the ilium Insertion: Anterior medial surface of the tibia (Pes anserine Tendon) Action: Flexion at the knee Internal Rotation Abduction of Hip (hackey sack) Popliteus Origin: Lateral condyle of the femur Insertion: Proximal medial tibia Action: Flexion of the knee It "unlocks" the knee. Gastrocnemius Origin: medial and lateral femoral condyles Insertion: the calcaneus through the Achilles tendon Actions: Flexion of the knee Posterior Review Superficial Leg Muscles Superficial Leg Muscles GET OUT YOUR THREE PACKETS TEST NEXT CLASS Sartorius Action: Flexion at the knee Name the muscle and its action(s) Terms Valgus Varus Stress to lateral side of the knee Stress to the medial side of the knee Semimembranosus Action: Flexion of the knee Name the muscle and its action(s) 1. Anterior cruciate ligament 2. Lateral collateral ligament 3. Lateral meniscus 4. Posterior cruciate ligament 5. Medial collateral ligament 6. Medial meniscus Semitendinosus Action: Flexion of the knee Name the muscle and its action(s) = PCL 2 = Lateral meniscus 3 = ACL 4 = Medial meniscus 2 = Vastus lateralis 1 = Rectus femoris 4 = Vastus medialis Name the colored muscles Femur ? = Lateral condyle Medial condyle Intercondylar fossa Gracilis Action - flexion at the knee Name the muscle and its action(s) Tibia Medial condyle Lateral condyle Medial Malleolus? = ? = = Vastus lateralis 2.= Rectus femoris 3.= Vastus medialis VLRFVM Rectus femoris Actions: Extension of the knee Name the muscle and its action(s) = Anterior cruciate ligament 2. = Lateral collateral 3. = Lateral meniscus 3. = Medial collateral 4. = Medial mieniscus Fibula Head Lateral malleolus ? = Biceps femoris Biceps femoris Semitendonosis Semimembranosis Name the muscles Biceps femoris Action: Flexion of knee Name the muscle and its action(s) Tibia Medial condyle Lateral condyle Medial Malleolus ? = Popliteus Action: Flexion of the knee Name the muscle and its action(s) Femur 6 = ? 7 = ? 8 = ? Lateral condyle Intercondylar fossa Medial condyle