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Anatomy of the Knee Joint

Anatomy of the Knee Joint

Largest and most superficial

Hinge type of synovial joint

Flexion and extension

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Articulations, Articular Surfaces and Stability

3 articulations: Femorotibial articulations (lateral and medial)Femoropatellar articulation

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Femorotibial

Femoropatellar

Articular surfaces2 femoral condylesthe adjacent surfaces of the superior aspect of the tibial condylesanterior surface of the distal end of the femur where the two condyles join adjacent surfaces on the posterior aspect of the patella

StabilityQuadriceps femoris - Inferior fibres of vastus medialis and lateralis

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Joint Capsule

Fibrous capsuleIt covers the joint on the lateral, medial and posterior aspect

Synovial membraneLines the inner surface of capsule

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Extracapsular Ligaments

Patellar ligamentMedial collateral ligamentLateral collateral ligamentOblique popliteal ligamentArcuate popliteal ligament

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Intra-articular LigamentsCruciate ligamentAnterior cruciate ligamentPosterior cruciate ligament

MenisciMedial meniscusLateral meniscus

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Movements

Flexion – Hamstrings, short head of biceps, gracilis, sartorius, gastrocnemius, popliteus

Extension – Quadriceps femorisMedial rotation – Semitendinosus,

semimembranosus, long head of biceps when FLEXED ;popliteus when non-bearing knee is EXTENDED

Lateral rotation – Biceps femoris when knee is FLEXED

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Locking and Unlocking

Locking is a mechanism that allows the knee to remain in the position of full extension

Locking occurs as a result of medial rotation of femur during last stage of extension

Locking is produced by quadriceps femoris

Unlocking occurs as a result of lateral rotation of femur during initial stage of flexion

Unlocking is produced by popliteus muscle

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Blood Supply10 vessels that form the periarticular genicular anastomoses around the knee

InnervationArticular branches from femoral, tibial, and common fibular nervesObturator and saphenous nerves

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Bursae

SuprapatellarPopliteusAnserineGastrocnemiusSemimembranosusSubcutaneous prepatellarSubcutaneous infrapatellarDeep infrapatellar

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