Chapter 10 The Knee Joint

Rectus Femoris?

*Football kicker invariably leans well backward to raise and fix the rectus femoris origin to make it more effective as a knee extensor

External Rotation?

-rotary movement of leg laterally away from the midline

Popliteus Actions?

Flexion of the knee Internal Rotation of the knee as it flexes

What is the proper name for the knee joint?

Tibiofemoral Joint

Vastus Intermedius Insertion

Upper border of the patella and patellar tendon to the tibial tuberosity

Antagonist to quadricep muscles are mostly located where?

knee

Strength and Endurance is important for what stability?

patellofemoral

What is the largest of the four quadriceps muscles?

vastus lateralis

Knee Flexion Agonist

-Biceps Femoris -Semitendinosus -Semimembranosus

List the four biarticular muscles?

-hamstring -Sartorius -Gracilis -Rectus Femoris

Vastus Medialis Origin

whole length of the linea aspera and the medial condyloid ridge

The knee does what, to fully extend due to larger medial femoral condyle?

-"screw home"

Knee External Rotation Agonist

-Biceps Femoris

Relationship of ACL & PCL?

-Cross within knee between tibia and femur -Vital in maintaining anterior/posterior stability

Rectus Femoris Actions

-Extension of the knee -Flexion of the hip -anterior pelvic tilt

What three bones make up the knee joint?

-Femur -Tibia -Patella

Name the four movements of the knee joint?

-Flexion/ Extension -External/Internal Rotation

Movements of the Knee Joint?

-Flexion/ Extension -Internal/External Rotation during flexion

Another name for the Knee Flexors Group?

-Hamstring Muscle Group

Sartorius Muscle?

-Increases total length and becomes a better flexor at knee when pelvis is rotated posteriorly and stabilized by abdominal muscles *exemplified by trying to flex knee and cross the legs in the sitting position *one usually leans backward to flex legs at knees

Initial Flexion from Full Extension?

-Knee "unlocks" by tibia rotating internally from its externally rotated position to achieve flexion (popliteus)

The Knee Joints stability?

-Ligaments provide static stability -Quadriceps and Hamstring contraction produce dynamic stability -Articular cartilage surfaces on femur and tibia -Menisci forms cushion between bones *Attached to tibia (plateau) *Deepen tibial fossa

Another name for the Knee Extensors?

-Quadriceps Muscle Group

Knee Extension Agonist

-Rectus Femoris -Vastus Lateralis -Vastus Medialis -Vastus Intermedius

What four muscles make up the Quadriceps Muscle Group/ Knee Extensors?

-Rectus Femoris (Hip Flexor) -Vastus Lateralis -Vastus Medialis -Vastus Intermedias

Other knee flexors?

-Sartorious (hip flex)+ Gracilis (hip add) -Popliteus -Gastrocnemius(weak knee flexor)

Knee Internal Rotation agonist

-Semitendinosus -Semimembranosus -Popliteus

What three muscles make up the Knee Flexors?

-Semitendinosus-medial/internal rotator -Semimembranosus-medial/internal rotator -Biceps Femoris-lateral/external rotator

Rectus Femoris Insertion

-Superior aspect of the patella and patellar tendon to the tibial tuberosity

Full Extension of the Knee?

-Tibia externally rotates 10 degrees to achieve alignment of tibial/femoral condyles -Close congruency of articular surfaces -No appreciable rotation of knee possible

Two important roles of the quadriceps muscles?

-allows rapid extension of the knee *vital in vertical jumping -important decelerator *eccentric contractor when functioning as a decelerator *decreases speed, when coming down from a jump

Q Angle?

-angle is formed at the patella -females have higher angles because of wider pelvis -central line of pull for quads run from ASIS to center of patella -Line of pull from patella tendon runs from center of patella to center of tibial tuberosity

Rectus Femoris Origin

-anterior /inferior iliac spine of the ilium and superior margin of the acetabulum

The patellofemoral joint is classified as what type of joint?

-arthrodial, due to its gliding nature of the on the femoral condyles

Quadriceps are more prone to what, following knee injury?

-atrophy

What three functions does the fibula serve to the knee joint?

-attachment for knee joint structures *not apart of the knee joint

Flexion?

-bending or decreasing angle between femur and leg, characterized by heel moving toward buttocks

Two Joint Muscles are known as what?

-bi articular

Biceps Femoris Actions?

-flexion of knee -internal rotation of flexed knee -extension of hip -internal rotation of hip -posterior pelvic tilt

Semimembranosus Actions?

-flexion of knee -internal rotation of flexed knee -extension of hip -internal rotation of hip -posterior pelvic tilt

Semitendinosus Actions?

-flexion of knee -internal rotation of flexed knee -extension of hip -internal rotation of hip -posterior pelvic tilt

What type of joint is the knee joint classified as?

-ginglymus, because it functions like a hinge

Fibular/ Lateral Collateral Ligament (LCL)

-infrequently injured

PCL (Posterior Cruciate Ligament)

-injured less often than the ACL -injury mechanism involves direct contact with an opponent or playing surface -Posterior Drawer Test=excessive backward movement of tibia

Biceps Femoris Origin?

-ischial tuberosity -lower half of linea aspera, lateral condyloid ridge

3 main facts concerning the knee joint?

-it is complex -it is primarily considered a hinge joint -"modified joint"

Neither internal/external rotation will occur unless, what?

-knee is flexed less than 20-30 degrees

Tibial/ Medial Collateral Ligament (MCL)

-maintains medial stability by preventing knee from being abducted -injured commonly in contact or collision sports *teammate or opponent may fall against lateral aspect of knee or leg causing medial opening of the knee joint

Two facts about the Tibia?

-medial bone of lower leg -Bears most of body weight

ACL (Anterior Cruciate Ligament)

-one of the most common serious injuries to the knee -Injury mechanism involves forces associated with hyperextension or anterior movement of the tibia -Anterior Drawer Test=Excessive forward movement of tibia

What hamstring muscle is known as the "unscrewer"/ initial flexor?

-popliteus

Higher Q Angle does what?

-predispose people to a variety of knee problems -maintain high levels of strength and endurance in vastus medialis to counteract lateral pull of vastus lateralis

List the four quadriceps muscles?

-rectus femoris -vastus lateralis -vastus intermedias -vastus medialis

How is atrophy developed?

-resisted knee extension activities from a seated position

Internal Rotation?

-rotary movement of leg medially toward the midline

List the three Hamstring muscles?

-semitendinosus -semimembranosus -biceps femoris

Internal Rotators Muscles?

-semitendinosus -semimembranosus -popliteus

What functions does the patella serve to the knee joint?

-serves as a pulley in improving angle of pull for quads -gives a greater mechanical advantage in knee extension -known as a sesamoid/floating bone -imbedded in quadriceps, and patellar tendon

Key Bony Landmarks for the Knee Joint?

-tibial tuberosity -Gerdy's Tubercle -Medial/ Lateral Femoral Condyles

The knee joint is sometimes classified as what? And why?

-trochoginglymus -because of the internal, and external rotation movements that can occur during flexion

Quadriceps muscles desire to be how much stronger than hamstring muscles?

25-33 %

External Rotator Muscles?

Biceps Femoris

What is the "tibial plateau"?

Enlarged femoral condyles articulate on enlarged tibial condyles

Vastus Intermedius Actions

Extension of the knee

Vastus Lateralis Actions

Extension of the knee

Vastus Medialis Actions

Extension of the knee

Vastus Lateralis Insertion

Lateral Border of the patella and patellar tendon to the tibial tuberosity

Vastus Medialis Insertion

Medial half of the upper border of the patella and patellar tendon to the tibial tuberosity

What quad muscle is also known as the vastus medialis obliquus (VMO)

Vastus Medialis

Hamstring muscles primarily function in what?

acceleration

Semitendinosus inserts where?

anteromedial tibia

Hamstring muscle strains are considered what?

common

Vastus Lateralis Origin

intertrochanteric line, anterior/inferior borders of the greater trochanter

Semimembranous origin?

ischial tuberosity

Semitendinosus Origin?

ischial tuberosity

All hamstring muscles originate where?

ischial tuberosity of pelvis

Biceps Femoris inserts where?

lateral tibial condyle/head of fibula

To a degree, muscles are able to exert greater force when?

lengthened slightly beyond resting length; rather than shortened

Popliteus Origin?

posterior surface of the lateral condyle of the femur

Semimembranosus inserts where?

posteromedial tibia

What is one way to tear the menisci?

significant compression and shear forces during rotation while flexing or extending during quick directional changes in running

Popliteus Insertion?

upper posterior medial surface of the tibia

Vastus Intermedius Origin

upper two thirds of the anterior surface of the femur

Extension?

Straightening or Increasing angle between femur and lower leg