Chapter 9: The knee joint
Genu varum
"bow legged" medial stress
Genu valgum
"knock-kneed" lateral stress
External rotation degrees with knee flexed 30+ degrees
45
Gracilis, sartorius, and semitendinosus join together distally to form...
pes anserinus
knee extension agonists
rectus femoris, vastus lateralis, vastus intermedius, vastus medialis
Anterior: primarily knee extension
rectus femoris, vastus medialis, vastus intermedius, vastus lateralis
Hamstring muscle group
responsible for knee flexion, located in the posterior compartment of the thigh Consists of 3 muscles -semitendinosus -semimembranosus -biceps femoris
Patella
sesamoid or floating bone, imbedded in quadriceps and patellar ligament, created improved angle of pull resulting in greater mechanical advantage in knee extension
Quadriceps muscle group
- extends knee - located in anterior compartment of thigh - consists of 4 muscles rectus femoris vastus lateralis vastus intermedius vastus medialis
knee flexion agonists
-Biceps femoris (long and short head) -Semitendinosus -Semimembranosus -Popliteus
Knee flexion occurs to _______ degrees
150
Knee extends to ______ degrees
180, hyperextension of 10 degrees or more is not common
Internal rotation degrees with knee flexed 30+ degrees
30
Posterior: primarily knee flexion
Biceps femoris Semimembranosus Semitendinosus Sartorius Gracilis Popliteus Gastrocnemius
medial menisci shape
C-shaped
Q angle
Central line of pull for entire quadriceps runs from ASIS to the center of patella Line of pull of patella tendon runs from center of patella to center of tibial tuberosity Angle formed by the intersection of these two lines at the patella is the Q angle
lateral menisci shape
O shaped
Patellofemoral joint
arthrodial owing to the gliding nature of the patella on the femoral codyles
Flexion
bending or decreasing the angle between the femur and leg; characterized by heel moving toward buttocks
knee external rotation agonists
biceps femoris
Menisci form
cushions between bones, attached to tibia, deepen tibial plateaus, enhance stability
Who generally has a higher Q angle?
females, due to wider pelvis
Lateral collateral ligament (LCL)
infrequently injured
anterior cruciate ligament (ACL)
injured most
the knee joint is the
largest diarthrodial joint, very complex, and primarily a hinge joint
Fibula
lateral: serves as the attachment for knee joint structures, does not articulate with the femur or patella, not part of knee joint
infrapatellar fat pad
lies posterior to the patellar tendon, insertion point for synovial folds of tissue known as "plica"; absorption of forces
Medial collateral ligament (MCL)
maintains medial stability by resisting valgus forces or preventing knee joint abduction
Tibia
medial bone: bears most of the weight
posterior cruciate ligament (PCL)
not injured often
External rotation
rotary movement of the leg laterally away from the midline
Internal rotation
rotary movement of the leg medially toward the midline
Extension
straightening or increasing the angle between the femur and leg
How to fix a knee hyperextension
strengthen posterior side of knee (hamstrings and calves)
Synovial cavity
supplies the knee joint with synovial fluid, lies under the patella and between the surfaces of the tibia and femur, called capsule of the knee
Knee joint or the
tibiofemoral joint, ginglymus joint
knee internal rotation agonists
Semitendinosus Semimembranosus Popliteus