The knee joint is the largest joint in the body. It has three articulations: the femorotibial articulations on the lateral and medial sides, and the femoropatellar articulation. The knee joint allows for flexion and extension movements and contains articular surfaces on the femoral condyles that interact with the tibia. Ligaments such as the cruciate ligaments and menisci provide stability to the joint, which is surrounded by a joint capsule lined with synovial membrane. Muscles like the quadriceps and hamstrings are responsible for extension and flexion of the knee.

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Anatomy of the Knee Joint

2. Anatomy of the Knee Joint
Largest and most
superficial
Hinge type of
synovial joint
Flexion and
extension
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3. Articulations, Articular Surfaces
and Stability
3 articulations:
Femorotibial articulations (lateral and medial)
Femoropatellar articulation
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Femorotibial
Femoropatellar

4. Articular surfaces
2 femoral condyles
the adjacent surfaces of the
superior aspect of the tibial
condyles
anterior surface of the distal end
of the femur where the two
condyles join
adjacent surfaces on the
posterior aspect of the patella
Stability
Quadriceps femoris - Inferior
fibres of vastus medialis and
lateralis
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5. Joint Capsule
Fibrous capsule
It covers the joint on
the lateral, medial and
posterior aspect
Synovial membrane
Lines the inner
surface of capsule
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6. Extracapsular Ligaments
Patellar ligament
Medial collateral ligament
Lateral collateral ligament
Oblique popliteal ligament
Arcuate popliteal ligament
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8. Intra-articular Ligaments
Cruciate ligament
Anterior cruciate ligament
Posterior cruciate ligament
Menisci
Medial meniscus
Lateral meniscus
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9. Movements
Flexion – Hamstrings, short head of biceps,
gracilis, sartorius, gastrocnemius, popliteus
Extension – Quadriceps femoris
Medial 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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10. 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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12. Blood Supply
10 vessels that form
the periarticular
genicular anastomoses
around the knee
Innervation
Articular branches
from femoral, tibial, and
common fibular nerves
Obturator and
saphenous nerves
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13. Bursae
Suprapatellar
Popliteus
Anserine
Gastrocnemius
Semimembranosus
Subcutaneous prepatellar
Subcutaneous infrapatellar
Deep infrapatellar
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