THE KNEE JOINT Muscles That Act On The

THE KNEE JOINT Muscles That Act On The Knee

Muscles of the Knee Joint p Hamstrings n p Quadriceps n p All - flexion All - extension Unclassified n n Sartorius - flexion and internal rotation Gracilis - flexion and internal rotation Popliteus - flexion (unlocking) and internal rotation Gastrocnemius - flexion

Anterior Muscles p Quadriceps n knee extension

Quadriceps Muscles

Rectus femoris p p 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: n Extension of the knee

Vastus lateralis p p p Origin: Lateral lip of linea aspera. Insertion: Outer half of the upper border of the patella and the patellar ligament and the anterior tuberoscity of the tibia Action: n Extension of the knee

Vastus intermedius Origin: Upper 2/3 of the anterior surface of the femur p Insertion: Upper border of the patella and the patellar ligament p Action: p n Extension of the knee

Vastus medialis p p p Origin: Medial lip of the linea aspera and the internal condyloid ridge Insertion: Inner half of the upper border of the patella nd patellar ligament Action: n Extension of the knee

VL RF VM

Quadriceps • Vastus Lateralis • Vastus Intermedius • Rectus Femoris • Vastus Medialis 1 2 3 Hamstrings

QUADRICEPS MUSCLES Vertical jumping p Decelerating or eccentric contraction during landing or changing directions p As a group, they are typically 25 -30% stronger than the hamstrings p

Posterior Knee Muscles

Hamstrings p knee flexion

Biceps femoris p p Lateral side Origin: n n p p 1. ) Long head - ischial tuberosity; 2. ) Short head - lower half of the linea aspera Insertion: Head of the fibula Action: n Flexion of knee

Semitendinosus p p Medial side; superficial Origin: Ischial tuberosity Insertion: Anterior medial surface of the tibia Action: n Flexion of the knee

Semimembranosus p p Medial side, deeper than semitendonosus Origin: Ischial tuberosity Insertion: Anterior medial surface of the tibia Action: n Flexion of the knee

HAMSTRING MUSCLES More “knee flexors” than “hip extenders” p Acceleration muscles during running p Tight hamstring muscles can contribute to lower back, hip and knee problems p

Gracilis O: Pubis crest p I: Anterior medial surface of the tibia p Actions: p n flexion at the knee

Sartorius p p Posterior at the knee joint Origin: Anterior-superior spine of the ilium Insertion: Anterior medial surface of the tibia Action: n n Flexion at the knee From Late Latin sartor, tailor (from its producing the cross-legged position of a tailor at work)

Popliteus Origin: Lateral condyle of the femur p Insertion: Proximal third of posterior aspect of the tibia p Action: p n Flexion of the knee n p It "unlocks" the knee. Only true knee flexor

Gastrocnemius Origin: posterior surface of the medial and lateral femoral condyles p Insertion: the calcaneus through the Achilles tendon p Actions: p n Flexion of the knee Posterior

Review p Superficial Leg Muscles

Name the muscle and its action(s) Sartorius Action: Flexion at the knee

Terms 1. 2. 3. Q Angle Valgus Varus 1. 2. 3. The deviation between the line of pull of the rectus femoris and the patellar ligament. Stress to lateral side of the knee Stress to the medial side of the knee

Name the muscle and its action(s) Semimembranosus p Action: n Flexion of the knee

1. 2. 3. 4. 5. 6. Anterior cruciate ligament Lateral collateral ligament Lateral meniscus Posterior cruciate ligament Medial collateral ligament Medial meniscus 1. 4. 2. 5. 3. 6.

Name the muscle and its action(s) Semitendinosus p Action: n Flexion of the knee

1 = PCL 2 = Lateral meniscus 3 = ACL 4 = Medial meniscus 1. 4. 2. 3

Name the colored muscles 2 = Vastus lateralis 1 = Rectus femoris 4 = Vastus medialis

Femur ? = ? = Lateral condyle Medial condyle Intercondylar fossa

Name the muscle and its action(s) Gracilis Action - flexion at the knee

? = Medial condyle ? = Lateral condyle ? = Medial Malleolus Tibia

2. 1. 3. 1. = Vastus lateralis 2. = Rectus femoris 3. = Vastus medialis

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Name the muscle and its action(s) Rectus femoris p Actions: n Extension of the knee

1. 2. 3. 4. 1. = Anterior cruciate ligament 2. = Lateral collateral 3. = Lateral meniscus 3. = Medial collateral 4. = Medial mieniscus

Name the muscles. 1 = Vastus lateralis 2 = Vastus intermedius 1. 2. 3 = Vastus medialis 3.

? = Head ? = Lateral malleolus Fibula

Name the muscles 1. 2. 3. 4. Biceps femoris Semitendonosis Semimembranos is

Name the muscle and its action(s) Biceps femoris p Action: n Flexion of knee

Tibia ? = Medial condyle ? = Lateral condyle ? = Medial Malleolus

Name the muscle and its action(s) Popliteus p Action: n Flexion of the knee

Femur 6=? 7=? 8=? Lateral condyle Intercondylar fossa Medial condyle

Name the muscle and its action(s) Sartorius Action: Flexion at the knee

3. 4. 1. 2. 1 = Medial meniscus 2 = PCL 3 = ACL 4 = Lateral meniscus