Exam 3 - Knee Anatomy Flashcards
Main points about the knee
- Largest synovial joint in the body
- separates the body’s two largest lever arms
- compound joint - tibiofemoral joint - patellofemoral joint
- patella largest sesamoid bone
- patella acts as a pulley - gives mechanical advantage to quads
What are the principle movements of the knee?
flexion
extension
rotation
What is the “screw-home mechanism”?
during knee extension, the tibia externally rotates to increase stability
What gives the tibiofemoral joint its stability?
- static restraints from the bones and ligaments
- dynamic restraints
Describe the anatomy of the meniscus
- semilunar cartilage
- the MEDIAL meniscus is “C-shaped”
- the LATERAL meniscus is “O-shaped”
- overall wedge shaped
What are the attachment points of the lateral meniscus?
- intercondylar area - attaches to PCL
- posterior - medial femoral condyle via meniscofemoral ligament
How is the medial meniscus attached?
- anterior - anterior tibia
- posterior - posterior tibia
What is the common mechanism of injury to the meniscus?
Loaded-twisting motion
What are the primary symptoms of a meniscus injury?
- report that the knee “gave out”
- clicking or popping sound
- effusion
- deep squat/duck walk painful
Between the medial and lateral meniscus, which is more commonly injured?
medial
How does the meniscus receive its blood supply?
- outer 1/3 from genicular artery
2. inner 2/3 is avascular, and receives nourishment from synovial fluid
What 4 muscles are responsible for extension of the knee?
- rectus femoris
- vastus lateralis
- vastus medialis
- vastus intermedius
What are the 3 primary muscles involved in knee flexion?
Hamstrings
- biceps femoris
- semitendonosis
- semimembranosis
What are the secondary muscles involved in knee flexion?
- gastrocnemius
- gracilis
- sartorius
What is the function of a bursa?
It’s a fluid-filled sac in high-friction areas that eases the friction of the muscles and tendons over body prominences
What are the 3 bursa of the anterior knee?
- suprapatellar bursa
- prepatellar bursa
- infrapatellar bursa
What is a plica?
distinct permanent fold of the synovium of the knee
What is the mechanism of injury for the plica?
- direct blow
- tear from a twist
- repeat stress
- weak vastus medialis & vmo
- hamstring tightness
What is the infrapatellar fat pad?
- largest fat pad in knee
- serves as a cushion to the front of the knee
- separates the patellar ligament from the joint capsule
- can become enlarged if irritated
What are the main ligaments in the knee?
LCL - lateral collateral ligament MCL - Medial collateral ligament ACL - Anterior cruciate ligament PCL - Posterior cruciate ligament Oblique popliteal ligament Patellar ligament
What is the function and attachment points of the LCL?
Provides lateral stability
Attachments:
- lateral condyle of the femur
- head of the fibula
What are the attachments and function of the MCL?
Provides medial stability Attachments: - medial condyle of femur - medial meniscus - medial tibia
What are the deep fibers of the MCL?
Menisco-femoral
Menisco-tibial
What is the MOI of the MCL?
valgus force from the lateral side
What is the function of the ACL?
prevents tibia from translating anteriorly on the femur
What are the 2 major fiber bundles of the ACL?
Anteromedial
Posterolateral
What are the attachments for the ACL?
Distal - anteromedial bundle at tibial intercondylar area
- ascends posterolaterally twisting on itself
Proximal - posteromedial aspect of the lateral femoral condyle
What is the function of the PCL?
Key stabilizer for basic knee motion/function
- creates compressive forceacross the knee joint between the tibia and femur
What are the attachments of the PCL?
distal - posterior tibial intercondylar area
- ascends anteromedially
proximal - lateral surface of the medial femoral condyle
What is the function and attachments of the Oblique popliteal ligament?
Provides posterior stability
Attachments:
Distal - posterior medial aspect of tibia
Proximal - posterior lateral aspect of femur
Patellar ligament attachments
Distal - tibial tuberosity
Proximal - inferior pole of patella
Bones of the knee
- medial condyle of femur
- medial condyle of femur
- patella
- medial & lateral joint lines
- medial condyle of tibia
- lateral condyle of tibia
- tibial tuberosity
- shaft of tibia
- head of fibula
- shaft of fibula
muscles of the knee
- vastus medialis
- rectus femoris
- vastus lateralis
- biceps femoris
- semitendinosus
- semimembranosus
- gastrocnemius
- tibialis anterior
Ligaments of the knee
- medial collateral ligament
- lateral collateral ligament
- patellar ligament
- oblique popliteal ligament
