Chapter 8, Section 3 The Knee Joint and Joint Disorders
Knee Joint The 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.
Figure 8.21
The femur also articulates anteriorly with the patella. This is a plane joint.
Figure 8.20
Knee Joint General Structures of a Synovial Joint in the Knee
1. Synovial Membrane • Secretes synovial fluid 2. Joint Cavity • Stores synovial fluid 3. Joint Capsule • Relatively thin support • Reinforced by several ligaments and tendons
Figure 8.20
Knee Joint Several ligaments and tendons strengthen the knee joint. Ligaments include: 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
Ligaments: 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 Figure 8.21a Anterior right knee with patella removed.
Knee Joint Two menisci (medial & lateral) 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)
Knee Joint
Three major bursae surround the 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
Sprain = overstretching or tearing of connective tissue (tendons, ligaments, or cartilage) associated with a joint. However, the bones are not disarticulated.
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.
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.
Other symptoms of Rheumatoid Arthritis: • low-grade fever, fatigue, appetite, stiffness.
End of Chapter 8, Section 3