meniscus biomechanics tamil bpt 2nd year | скачать в хорошем качестве

meniscus biomechanics tamil bpt 2nd year |

Menisci The menisci are fibrocartilaginous discs with a semicircular shape. The medial meniscus is C-shaped, whereas the lateral meniscus forms four fifths of a circle. Tibiofemoral incongruence is improved by the presence of medial and lateral menisci, which act to transform the convex tibial plateaus into concavities for the femoral condyles. Both menisci are open toward the intercondylar tubercles and are thick peripherally and thin centrally. The lateral meniscus covers a greater percentage of the smaller lateral tibial surface than the surface covered by the medial meniscus. As a result of its larger exposed surface, the articular cartilage of the medial tibial plateau not covered by meniscus carries a greater load during routine daily activities than that of the lateral tibial plateau, making it more susceptible to injury. FUNCTIONS ÷ (a) Stability function: the menisci of the knee joint enhance the contact surface area of the joint thereby increasing the joint congruency. The movement of femoral condyle would produce less pressure over the tibia as the surface area is more. (b ) Mobility function: The wedge shape of the menisci allows the femoral condyles to ride over it during gliding and rotation. The ability of the menisci to deform and remain intact between the articulating surfaces helps the joint to move very smoothly with less friction. C) menisci play a important role in shock absorbption , transmitting weight bearing load , reduce friction ( between tibia and femur) and enhancing joint stability MENISCAL ATTACHMENTS ÷ The anterior and posterior ends of the meniscus are called the anterior and posterior horns. Anteriorly the menisci are connected to each other by the transverse Ligament Both menisci are also attached directly or indirectly to the patella via the patellomeniscal ligaments . At the periphery, the menisci are connected to the tibial condyle by the coronary ligaments, The medial meniscus is firmly attached to the medial joint capsule through a capsular thickening referred to as medial collateral ligament. The anterior and posterior horns of the medial meniscus are attached to the anterior cruciate ligament and posterior cruciate ligament. MENISCAL NUTRITION AND INNERVATION ÷ During the first year of life, blood vessels are contained throughout the meniscal body. After 50 years of age, only the periphery of the meniscal body is vascularized. Therefore, the peripheral portion obtains its nutrition through blood vessels, but the central portion must rely on the diffusion of synovial fluid. The horns of the menisci and the peripheral vascularized portion of the meniscal bodies are well innervated with free nerve endings (nociceptors) and three different mechanore- ceptors (Ruffini corpuscles, Pacinian corpuscles, and Golgi tendon organs),