knee ligaments Flashcards

1
Q

general functions of the ligaments

A

limit excessive knee extension

limit varus and valgus stresses

limit anterior and posterior translation of the tibia beneath the femur (also the femur on the tibia)

limits medial and lateral rotation of the tib on the femur

check rotary instabilities (combo of A-P translations and rotations –> stability in more than one direction)

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2
Q

ligaments in OKC

A

limit tibial motion

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3
Q

ligaments in CKC

A

limit femoral motion

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4
Q

medial collateral ligament (MCL)

A

runs from the medial femoral epicondyle

slopes anteriorly

inserts into the medial aspect of the proximal tibia

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5
Q

where does the MCL have attachments

A

joint capsule

medial meniscus

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6
Q

when is the MCL tight

A

full knee extension

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7
Q

primary function of MCL

A

resists valgus stress both in flexion and extension

contribution to valgus stability when flexed**
–> other structures in the knee have less contribution

will resist hyperextension of the knee

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8
Q

secondary fxns of MCL

A

will check lateral rotation of the tib

back up restraint to pure anterior displacement of tibia when ACL is absent

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9
Q

lateral collateral ligament (LCL)

A

runs from the lateral femoral epicondyle to the head of the fibula

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10
Q

where does the LCL have attachments

A

no where

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11
Q

when is the LCL tight

A

full knee extension

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12
Q

primary fxn of LCL

A

resist knee varus

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13
Q

secondary fxn LCL

A

resists medial rotation of the tibia

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14
Q

anterior cruciate ligament (ACL)

A

runs from the anterior tibia

between anterior insertions of the medial and lateral menisci

courses posteriorly, laterally and proximally across the knee joint

inserts on the medial aspect of the lateral femoral condyle

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15
Q

what happens as the ACL runs anterior to posterior

A

ACL turns outward in a slight spiral

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16
Q

how can the ACL be divided

A

anteromedial band

posterolateral band

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17
Q

anteromedial band of ACL

A

tightens with knee flexion

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18
Q

posterolateral band of ACL

A

tightens with knee extension

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19
Q

when can the ACL be torn

A

flexed or extended

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20
Q

where is the ACL

A

within the fibrous capsule but is extra synovial

outside the synovial layer –> not nourished by synovial fluid

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21
Q

primary fxn of ACL

A

resist anterior translation of the tibia on the femur

in knee joint flexion and extension

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22
Q

secondary fxn of the ACL

A

to limit tibial IR w/ knee in slight flexion

when all structures in the knee are in tact –> ACL plays a secondary role in preventing excessive tibial IR
–> IT band and lateral capsule are the primary restraints

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23
Q

what does the ACL have a small role in

A

resisting valgus and varus stress across the knee in the presence of deficiency of the collateral ligaments

when knee is in full extension

24
Q

posterior cruciate ligament (PCL)

A

runs from its posterior tibial attachment superiorly and somewhat anteriorly to the inner aspect of the medial femoral condyle

25
Q

how can the PCL be divided

A

anteromedial band

posterolateral band

26
Q

anteromedial band of the PCL

A

maximally tight in 80-90 degrees of knee flexion

27
Q

posterolateral band of the PCL

A

tight in extension

28
Q

where is the PCL

A

within the fibrous capsule by extra synovial

29
Q

PCL primary fxn

A

resist posterior displacement of the tibia on the femur

30
Q

secondary fxn of PCL

A

resists tibial rotations

especially when the knee is flexed

31
Q

what does the PCL play a small role in

A

resisting valgus and varus stressed across the knee

32
Q

posterior capsule ligaments

A

oblique popliteal ligaments

arcuate ligament

both are tight in full knee extension and assist in preventing knee hyperextension

will resist valgus and varus stress when the knee is extended

33
Q

oblique popliteal ligaments

A

runs from a point posterior to the medial tibial plateau to the central part of the joint capsule

34
Q

arcuate ligament

A

y-shaped structure

attaches distally on the fibular and fans over the posterior capsule to joint the oblique popliteal ligament

35
Q

joint capsule

A

has vertical fibers that are attached above the margins of the femoral condyles and the posterior margins of the tibial plateaus

36
Q

is the joint capsule lax or tight

A

extensive structure that is fairly lax

allows a great amount of motion

37
Q

how does the joint capsule extend

A

from the superior aspect of the quads tendon to the patellar ligament inferiorly

38
Q

what is the joint capsule reinforced by

A

muscles and ligaments

39
Q

extensor retinacula

A

the anteromedial and anterolateral portions of the capsule

also called the medial and lateral patella retinaculum

can affect patellar tracking

40
Q

general form of the capsule

A

compares to a cylinder which is invaginated posteriorly

41
Q

is the joint capsule innervated

A

highly innervated w/ mechanoreceptors

contributes to muscular stabilization of the knee joint by initiating reflex mediated muscular responses

42
Q

synovial lining

A

most extensive and involved in the body

will follow the fibrous layer of the capsule except posteriorly where the synovium invaginates anteriorly
–> results in the ACL and PCL being within the fibrous capsule but not within the synovial lining

43
Q

what will the synovial lining do during gestation

A

divide the knee into 3 compartments until 12 weeks of gestation

then the synovial septa are resorbed –> resulting in a sing joint cavity

44
Q

plica

A

septa that are not completely resorbed and remain through adulthood

can be a cause of knee pain

45
Q

when is the synovial lining most lax

A

when it has its greatest volume

approx 20-30 degrees of flexion
–> it can accommodate more fluid (has the greatest potential for fluid)
—-> contractures of the posterior muscles and structures
——–> keep knee extended after surgery

46
Q

bursae

A

suprapatellar

prepatellar

superficial infrapatellar

deep infrapatellar

pes anserine

gastrocnemius

subpopliteus

47
Q

suprapatellar

A

located b/w the femur and the quadriceps femoris muscle tendon

helps reduce friction b/w the two structures during knee extension

48
Q

prepatellar

A

lies over the patella

fxns to cushion the anterior surface of the patella against direct trauma and reduce friction b/w the patella and the skin

49
Q

superficial infrapatellar

A

lies b/w the patellar tendon and the skin

helps to reduce friction

50
Q

deep infrapatellar

A

lies b/w the patellar ligament and the tibia

51
Q

deep infrapatellar and superficial infrapatellar

A

facilitate gliding b/w those structures while we flex and extend the knee

reduce friction

52
Q

pes anserine

A

lies b/w the proximal anterior medial aspect of the tibia and the undersurface of the pes anserine muscle tendons

“gooses foot”

53
Q

gastrocnemius

A

lies b/w the medial femoral condyle and the medial gastroc tendon

54
Q

subpopliteus

A

lies b/w the tendon of the popliteus and the lateral condyle of the tibia

55
Q

infrapatellar fat pad

A

located at the anterior knee b/w the patellar tendon and the underlying synovial tissue and bone

acts as a cushion

highly innervated by nociceptors fibers –> irritation will cause pain