Layers of the knee

Medial side

outer layer

· consists of proximal continuation of deep fascia of thigh

· anteriorly

· blends with fibres from vastus medialis

· forms medial patellar retinaculum

· in middle

· splits to enclose sartorius

· posteriorly

· continous with deep fascia

· covers gastrocnemius and roof of popliteal fossa

Pes anserinus

· semitendinosus and gracilis run between superficial and middle layers

· insert into tibia under tendon of sartorius

· 3 tendons form pes anserinus

· part of outer layer

· bursa lies deep to tendon

middle layer

· consists of superficial medial collateral ligament

· superiorly

· fibres pass to medial patella

· form medial patellofemoral ligament

· posteriorly

· fibres merge with joint capsule and tendon of semimembranosus

Superficial MCL

· long thin well-delineated structure

· attached superiorly just below adductor tubercle of femur

· in line with adductor magnus

· attached inferiorly to subcutaneous border 6-10 cm below knee joint

Semimembranosus

· runs down across popliteal fossa

· inserts into tubercle on posterior aspect of medial tibial condyle

· four expansions from tibial insertion

· tibia x 2, femur, meniscus

1. oblique popliteal ligament

· extends upwards and laterally

· crosses popliteal fossa

· attaches to lateral femoral condyle

2. posteriorly

· inserts into posterior capsule and posterior horn of medial meniscus

3. anterior

· passes foward along medial surface of tibial plateau

· passes under superficial MCL

· attaches to tibia

4. over popliteus

· expansion passes down over popliteus muscle

· fuses with periosteum of medial tibia

Deep layer

· consists of joint capsule

· thickened medially by deep medial ligament

· posterior thickening called posterior oblique ligament

Deep MCL

· extends from medial epicondyle of femur to just below tibial articular margin

· deep to and separate from superficial MCL

· divided into

1. meniscofemoral portion

· from medial meniscal attachment to capsule

· to femoral origin

· longer and stronger

2. meniscotibial portion

· syn. coronary ligament

· from tibial attachment

· to medial meniscal attachment to capsule

Posterior oblique ligament

· extends from posterior edge of deep MCL to insertion of semimembranosus

· originates from adductor tubercle of femur

· has 3 insertions

1. central arm

· edge of posterior surface of tibia

2. superior arm

· continuous with posterior capsule

3. inferior arm

· attaches to sheath covering semimembranosus tendon

Lateral side

outer layer

· continuous with deep fascia

· in middle

· thickening of deep fascia called iliotibial band

· tendon of TFL and GMax

· inserts into smooth facet on lateral condyle of tibia

· called Gerdy’s tubercle

· sends fibres to reinforce lateral patellar retinaculum

· anteriorly

· blends with fibres from vastus lateralis

· forms lateral patellar retinaculum

· posteriorly

· splits to enclose biceps femoris

middle layer

· consists of superficial lateral collateral ligament

· runs from lateral epicondyle of femur to head of fibula

· superiorly

· fibres pass to lateral patella

· form lateral patellofemoral ligament

Deep layer

· consists of true capsule of joint

· thickened laterally by deep lateral collateral ligament

· runs from lateral femoral condyle to head of fibula

· thin and unimportant cf. superficial LCL

· capsular attachment to lateral meniscus called coronary ligament

· popliteus runs through hiatus in it

· posteriorly capsule divides into two layers

· superficial lamina ends in fabellofibular ligament

· runs from fabella to fibula

· runs parallel to LCL

· deep lamina ends in arcuate ligament

· Y-shaped

· originates from posterior capsule on distal femur

· medial limb passes to oblique popliteal ligament

· lateral limb to posterior fibula

Popliteus

· withdraws meniscus during flexion

· externally rotates femur during initial flexion

Origin

· popliteal surface of tibia above soleal line

Path

· tendon lies within joint capsule

Insertion

· 3 points of insertion

· pit in lateral condyle of femur (below LCL)

· posterior aspect of lateral meniscus

· head of fibula

Anterior

Quadriceps tendon

· inserts into proximal pole of patella

· four muscles of quadriceps form trilaminar tendon

· anterior lamina

· formed by rectus femoris

· flattens above patella

· posterior lamina

· formed by vastus intermedius

· intermediate lamina

· formed by confluent edges of vastus medialis and lateralis

· fibres of aponeurosis of vastus medialis insert directly into medial side of patellar tendon

patellar tendon

· originates from distal pole of patella

· inserts into tibial tuberosity