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The Knee Joint and Joint Disorders
Chapter 8, Section 3
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Knee JointThe knee joint is the largest and most complex synovial joint in body.
Two distal condyles of the femur articulate with two proximal condyles of the tibia. This is a condylar joint.
The femur also articulates anteriorly with the patella. This is a plane joint.
Figure 8.21 Figure 8.20
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1. Synovial Membrane• Secretes synovial fluid
2. Joint Cavity • Stores synovial fluid
3. Joint Capsule• Relatively thin support• Reinforced by several
ligaments and tendons
Knee Joint
General structures of a synovial joint in the knee
Figure 8.20
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1. Patellar tendon - The patella is partially enclosed in tendons fused together from the thigh muscle.
2. Patellar ligament – continuation of patellar tendon. Extends from patella to the tibial tuberosity.
Knee Joint
Several ligaments and tendons strengthen the knee joint.
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Knee Joint
Figure 8.21a Anterior right knee with patella removed.
3. Tibial collateral ligament – connects medial condyle of femur with medial condyle of tibia.
4. Fibular collateral ligament – connects lateral condyle of femur with head of fibula.
5. Anterior & Posterior Cruciate ligaments – provide additional support to medial surface of tibia and femur
Ligaments continued:
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Knee Joint
Two menisci (medial & lateral meniscus) separate the femur and tibia, and align them.
Figure 8.20 (a) sagittal section of the knee joint. (b) Photograph of the left knee joint (frontal
section)
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Three major bursae surround the knee joint.
Knee Joint
1. Suprapatellar bursa• Largest bursa in body
2. Prepatellar bursa• Between patella and skin• Housemaid’s knee =
prepatellar bursitis
3. Infrapatellar bursa
Figure 8.20a
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Joint Disorders
Sprain = overstretching or tearing of connective tissue (tendons, ligaments, or cartilage) associated with a joint.
However, the bones are not disarticulated.
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Joint Disorders
Arthritis = inflamed, swollen, and painful joints.
1. Osteoarthritis• Most common arthritis
• Occurs with aging
• Articular cartilage degenerates, causing bone to rub against bone.
• Results in stiff and painful joints
• Fingers may appear gnarled and knee may bulge.
Osteoarthritic fingers often take
on a gnarled appearance.
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2. Rheumatoid Arthritis• Autoimmune disorder (immune
system attacks tissue)
• Synovial membrane thickens & becomes inflamed
• Mass of fibrous connective tissue (Pannus) invades synovial space.
• Fibrous pannus destroys articular cartilage, and the joints may swell and ossify.
Knuckles may swell as a result of rheumatoid arthritis.
End of Chapter 8, Section 3
Other symptoms of Rheumatoid Arthritis:• low-grade fever, fatigue, appetite, stiffness.
Joint Disorders