2. The knee joint Flashcards
name the 2 articulations of the knee joint
- tibiofemoral: medial and lateral femoral condyles articulating with tibia
- patellofemoral: distal anterior femur with patella
what is the function of the patella
patella is formed inside quadriceps femoris tendon:
1- allows quadriceps femoris (main knee extensor) to be inserted directly over knee, increasing its efficiency
2- minimises wear and tear of tendon
which structures are found between the femur and tibia articulating surfaces
lateral and medial menisci (fibrocartilaginous)
what is the function of the knee menisci
1- deepen articular surface of tibia… increase joint stability
2- shock absorbers
how are the lateral and medial menisci attached
- Are attached at both ends to the intercondylar area of tibia.
- Anterior edges of menisci joined by transverse ligament of knee.
- Medial meniscus fixed to tibial (medial) collateral ligament and joint capsule (whilst lateral meniscus is smaller and has no extra attachments).
how can damage to the medial meniscus occur
tearing of medial collateral ligament
which ligament stabilises the patella and where does it attach
patellar ligament: continuation of quadriceps femoris tendon distal to patella and attaching to tibial tuberosity
which ligaments prevent lateral/medial mov. at the knee and where do these attach
- medial (tibial) collateral ligament - wide and flat, runs from medial epicondyle of femur to medial surface of tibia (also attaching to medial meniscus)
- lateral (fibular) collateral ligament - thinner and rounder, runs from lateral epicondyle of femur to depression on lateral surface of fibular head
which ligaments prevent anterior and posterior dislocation of femur on tibia and where do these attach
- anterior cruciate ligament: runs from anterior intercondylar region of tibia and ascends posteriorly to attach to intercondylar fossa of femur - prevents anterior dislocation of tibia to femur
- posterior cruciate ligament: runs from posterior intercondylar region of tibia and ascends anteriorly to attach to intercondylar fossa of femur - prevents posterior dislocation of tibia to femur
name the 4 bursae found at the knee joint and their location
- prepatella bursa - between apex of patella and skin
- suprapatella bursa - between quadriceps femoris tendon and femur
- infrapatella bursa - between patella ligament and skin (superficial) and between patella ligament and tibia (deep)
- semimembranosus bursa - posterior to knee joint, between semimembranosus and medial head of gastrocnemius
what are Housemaid’s knee and Clergyman’s knee
Housemaid’s knee = prepatella bursitis
Clergyman’s knee = infrapatella bursitis
name 5 extracapsular ligaments that strengthen the knee joint capsule
- patellar
- tibial collateral
- fibular collateral
- oblique popliteal
- arcuate popliteal
why is there relatively poor stability at the knee
curved femoral condyles lying on flat femoral head
which structures limit knee joint flexion
- tension of rectus femoris (esp. with hip joint extended)
- tension of vastus medialis, lateralis and intermedius
- soft tissue apposition posteriorly
which structures limit knee joint extension
- ligaments: ACL, PCL, lateral and medial collaterals and oblique popliteal
- posterior joint capsule
which structures limit knee joint internal rotation
ACL and PCL
which structures limit knee joint external rotation
lateral and medial collaterals
which muscles mediate knee flexion
- hamstrings
- popliteus
- gracilis and sartorius
which muscles mediate knee extension
quadriceps femoris
which muscles mediate knee lateral rotation
biceps femoris
which muscles mediate knee medial rotation
- semimemranosus and semitendinosus
- gracilis and sartorius
how does the knee ‘lock’
passive medial rotation of femur on tibia
how does the knee ‘unlock’
lateral rotation of femur on tibia due to popliteus contracting
why does the knee lock
- more adapted for weight bearing: required for standing and walking (loading response)
- thigh and leg muscles can relax briefly without making knee joint too unstable
