Unit 3 Knee Anatomy/Examination Flashcards
What is the largest synovial capsule in the body?
Knee joint capsule
- thin strong fibrous membrane
- capsule has expansions from the ligaments that pass over it
- extensive posteriorly and shorter/thicker on the side
What is the role of the Menisci
- Provide support and stability
- provide depth to the articular surfaces of the tibia so the larger femoral condyles sit with greater stability
Medial Meniscus
- Lunar shaped/ larger and thicker
- sits in the concave medial plateau
- wider in the back than in the front
Lateral Meniscus
- rounder more of an O shape
- sits in the convex lateral tibial plateau
- smaller and thinner
- more mobile
Functions of the Menisci
- reduce the compressive force across the tibiofemoral joint
- stabilize the joint during motion
- lubricate the articular cartilage
- provide support
Patellofemoral Joint Functions
- Provides the articulation with low friction
- protect the distal aspect of the femur from the trauma and the quadriceps from attritional wear
- improve cosmetic appearance of the knee
- improve the moment arm of the quadriceps and increase the extension torque
- Decrease the amount of anteroposterior tibiofemoral shear stress placed on the joint
How does having a patella make the quadriceps stronger ?
- lengthened by the patella which increases the torque
- patella improves the moment arm which is the distance between center of gravity and center of rotation of the quadriceps which increases the extension torque which then allows us to generate more power
- All of this is achieved by elevating the quadriceps from the center of knee rotation
- Patella just acts like a spacer between the patella and the quadriceps –> increasing the efficacy of the quads/ provides it with leverage so we can extend our knee
Anterior Cruciate Ligament
ACL
- Primary restraint for anterior translation of the knee/medial rotation of the tibia on the femur
- Secondary restraint for varus and valgus rotation of the tibia
- Attaches on the anterior intercondylar plateau
Posterior Cruciate Ligament
PCL
- Primary restrain for posterior translation and the medial rotation of the tibia
- secondary restrain to varus and valgus rotation of the tibia
- attaches to the posterior intercondylar plateau
Medial/Tibial Collateral Ligament
- Primary for valgus and lateral rotation of the tibia
- secondary restraint to the anterior and posterior translation of the tibia on the femur
Lateral/Fibular Collateral Ligament
- primary restraint for varus and lateral rotation of the tibia
- Secondary restrain to the anterior and posterior translation of the tibia on the femur
How do the cruciate ligaments receive sensory information?
Nerves:
- genicular
- common branches of the tibia
- peroneal
- obturator
Which is thicker and stronger the ACL or the PCL
PCL is stronger and thicker
- 50% thicker and 2x as strong compared to the ACL
Medial Collateral Ligament
MCL
- extra articular ligament
- Primary stabilizer of the medial side of the knee against valgus force and external rotation of the tibia especially when the knee is flexed
- Anterior fibers are taught in flexion
- Posterior fibers are taught in extension
Oblique Popliteal Ligament
Limits anterolateral rotation
Prevents hyperextension of the knee
