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
