menisci Flashcards
menisci are
biconcave fibrocartilaginous tissue b/w the articulating surfaces of the tibia and the femur
medial meniscus shape
semi-lunar ( C-shaped)
wider posteriorly than anteriorly
lateral meniscus
approx 4/5 of a circle
“horns”
open ends of the menisci
attached to the tibial intercondylar tubercles
how’re the medial and lateral menisci attached to the tibia
to their periphery by coronary ligaments
how’re the menisci attached to the patella
patellomeniscal or patellotibial ligaments
what attaches the anterior horns
transverse ligament
medial meniscus has attachments to
MCL and semitendinosus
lateral meniscus has attachments to
PCL
popliteus
medial femoral condyle
which menisci is more firmly attached
medial meniscus
can’t deform or move as much –> injured more often
wedged shaped
thicker at the periphery
thinner centrally
functions of the mensici
stability
lubrication and nutrition
shock absorption
mobility
vascularity
stability
the menisci deepen the fit b/w the relatively flat surfaces of the tibial plateaus and the convex surfaces of the femoral condyles
where is stability greatly important
lateral compartment
convex on convex (femoral condyles on tib)
–> meniscus improves stability
in a WB knee joint
the menisci transmits the majority of the load from the femur to the tibia
what does the menisci secondarily provide
restraint to anterior laxity
menisci improves stability by
increasing congruency of the tibiofemoral knee joint
increasing concavity of the tibial plateaus
increasing the articular surface area
lubrication and nutrition
the menisci act as buffers b/w the tibia and the femur
reduce the coefficient of friction b/w the joint surfaces
what helps lubricate the knee joint surfaces
triangular shape of the menisci
directing synovial fluid from the periphery to central portion of the joint
shock absorption
menisci will help distribute weight bearing forces
responsible for 40-60% of the imposed load on the body
pressure =
force / surface area
normal gait forces on the knee
2-3x BW
stairs and running forces on the knee
5-6x BW
mobility
menisci will deform during flexion/extension and rotation of the knee joint
wedge shaped menisci will aide in the gliding of the articular surfaces
in what direction will the menisci deform
opposite of the tibial plateaus
same direction as the femur
helps maintain joint congruity
why do the menisci distort as opposed to truly moving
d/t various attachments of the menisci
what happens during rotation
menisci follow the displacement of the femoral condyles
during lateral tibial rotation
the lateral meniscus moves toward the anterior portion of the tibial plateau while the medial meniscus moves posteriorly
meniscus follows displacement of the femoral condyles
during flexion CKC
the femur must glide anteriorly
the wedge shape of the menisci help to induce this anterior glide
medial meniscus are pulled posterior by semimembranosus
lateral meniscus is drawn posterior by popliteus tendon
during extension
the demur must glide posteriorly
wedge shape of the menisci help induce this posterior glide
menisci are pulled anteriorly by the meniscopatellar ligament –> transmit tension generated by the quads
which meniscus has more attachments
medial meniscus
moves A-P 5-7 mm
how much does the lateral meniscus move
11 mm
vascularity
entire meniscus is well vascularized until 10-11 yrs old
after, only the periphery is vascularized
vascularity has treatment implications
