Session 9: The Knee Joint

Question 1

Articulating surfaces in the knee joint

Answer 1

femoral: condyles: med. is bigger than lat. and takes more weight, between the two anteriorly is a shallow depression for patella articulation and posteriorly is an intercondylar fossa
- epicondyles: medial epicondyle provides an adductor tubercle; a large point of attachment for the adductor magnus, both epicondyles are the site of attachment for both med. and lat. coll. lig.s of knee joint

Tibial: plateau shape means joint is fairly weak, med. is slightly concave whereas lat. is slightly convex, separated by an intercondylar eminence that has tubercles that provide the attachment for lig.s and menisci

Question 2

name ligaments of knee joint

Answer 2

extracapsular: medial (tibial) and lateral (fibular) collateral, oblique and arcuate popliteal and patella ligaments
intracapsular: anterior and posterior cruciate ligaments

Question 3

extracapsular ligaments of knee joint

Answer 3

Medial/Tibial and Lateral/Fibular collateral: from med/lat. epicondyle of femur to med tibial condyle/lat surface of head of fibula, medial protects the med. side of knee from lat. force

Patellar: quad. fem. tendon distal to patella, attaches to tibial tuberosity

Arcuate and Oblique Popliteal: passes proximally to cross the tendon of the popliteal muscle/ radiation of tendon of semimembranosus on medial side, strengthens posterior aspect of knee capsule (along w/ arcuate)

in pic. oblique popliteal ligament is going from bottom left to top right, arcuate popliteal ligament is going

Question 4

intracapsular ligaments of knee joint

Answer 4

cruciates - PAMs APpLes:

Posterior: from Posterior intercondylar surface of tibia to the Anterior part of lat. side of the Medial condyle of femur, prevents H.flexion of leg and ant. displacement of femur on tibia

Anterior: from Anterior intercondylar surface of tibia to the Posterior part of the med. side of the Lateral condyle of the femur, prevents H.extension of leg and post. displacement of femur on tibia

Question 5

menisci

Answer 5

made of fibrocartilage

act to deepen surface of articulation and to act as a shock absorber

med. : C-shaped, attaches ant. and post. to intercondylar areas of tibia, also to tibial collateral ligament -> damage to TCL -> damage to med. meniscus
lat. : nearly circular, attaches to post. cruciate lig. by post. meniscofemoral ligament

Question 6

movements and locking of knee

Answer 6

flexion: hamstrings, gastrocnemius, sartorius, gracillis, popliteus
extension: quadricep muscles
lat. rotation at 90 degrees: biceps femoris
med. rotation at 90 degrees: semimembranosus
locking: femur rotates medially over tibial plateau when knee is fully extended so that the knee can be held in position
unlocking: popliteus helps to lat. rotate femur on tibia

Question 7

Injuries to ligaments of knee joint

Answer 7

collateral: ligament strain from force being applied to side of knee when foot is planted firmly on the ground
- > med and lat. rotate leg -> pain med. means MCL is damaged (and likely that med. meniscus is torn), pain lat. means LCL is damaged

–> unhappy triad: damage to MCL, ACL and medial meniscus caused by blows to side of knee forcing lateral rotation of flexed knee

Cruciate: ant.: large force to back of knee with joint partly flexed

• > test: anterior drawer test - attempt to pull tibia forwards
  post: H.extension leads to damage to upper part of tibial tuberosity
• > post. drawer test

Question 8

bursa in knee joint and bursitis

Answer 8

suprapatellar: extension of syn. cav. of knee between quadriceps. fem. and femur
(superficial) infrapatellar: between tib. tuberosity and skin
prepatellar: between apex of patella and skin
bursitis: friction between skin and patella -> prepatellar bursa is inflamed -> swelling on ant. side of knee (housemaid’s knee)

friction between skin and tibia -> inflamed infrapatellar, clergyman’s knee

Question 9

popliteal fossa contents, boundaries and clin. significance

Answer 9

contains, med. -> lat.: popliteal artery, popliteal vein, small saphenous vein, tibial nerve, common fibular nerve

boundaries: sup. lat.: biceps femoris, sup. med.: semimembranosus, inf.: lat. and med. heads of gastrocnemius, roof: popliteal fascia and skin, floor: posterior surface of knee joint capsule and femur
clin. significance: a popliteal artery aneurysm can damage tibial nerve in particular leading to leg anaesthesia/loss of leg motor function