Friday, October 25, 2019
The Anatomy and Actions of the Knee Essay -- essays research papers
The knee joint is formed by the articulation of the distal end of the femur and the proximal end of the tibia. The fibula is only involved to the extent that it serves as an attachment site for connective tissue. In this paper, the anatomy of the joint will be discussed. The knee is a hinge-type, diarthrotic, or freely moveable joint. Also referred to as a synovial joint, the 2 articulating ends of bone are encased in a capsule that lubricates the joint with synovial fluid to reduce friction. Each bone in a synovial joint has articular cartilage at the articulating surface. The C-shaped medial and lateral menisci serve to deepen the articulation at the superior surface of the tibia, thus enhancing the bony stability of the joint. Also adding to the joints stability are the two major pairs of ligaments: the cruciates and the collaterals. The medial and lateral collateral ligaments have a stabilizing effect in a lateral plane of motion, helping to prevent sideward displacement and over-rotation. The medial collateral attaches the femur to the tibia, also attaching to the medial meniscus. The lateral collateral attaches the femur to the fibula but has no attachment to the lateral meniscus. Both collaterals lie slightly posterior to the lateral axis of the knee joint and are taut when the knee is full extension. This positioning of the ligaments causes a slackness when flexion occurs, allowing medial and lateral rotation to take place. The cruciate ligaments are so named because of their cross-configuration within the joint. The anterior cruciate ligament attaches to the tibia on its anterior-superior surface, crossing through the joint from the medial side to its lateral attachment on the femur. The posterior cruciate ligament attaches on the posterior-superior aspect of the tibia, crossing diagonally and medially to its lateral attachment on the femur. The anterior and posterior cruciates protect against hyperextension and hyperflexion, respectively. The actions performed at the knee include flexion, extension, and medial and lateral rotation. Flexion is the bending of a joint so that the angle between the two bones decreases. The primary muscles that flex the knee are a group collectively known as â€Å"hamstrings.†The hamstrings consist of the biceps femoris, semitendinosus, semimembranosus. The muscles that assist in flexion are the sartorius, gracilis,... ...g     Linea aspera on posterior femur, greater trochanter of femur Insert     Patella and via patellar tendon to tibial tuberosity Action     Extension of knee Nerve     Femoral VASTUS INTERMEDIUS Orig     Anterior and lateral femoral shaft Insert     Patella and via patellar tendon to tibial tuberosity Action     Extension of the knee Nerve     Femoral VASTUS MEDIALIS Orig     Linea aspera on posterior femur Insert     Patella and via patellar tendon to tibial tuberosity Action     Extension of knee Nerve     Femoral TENSOR FASCIA LATA Orig     Iliac crest (posterior to ASIS) Insert     Iliotibial tract (which continues to attach to the lateral condyle of the tibia)      Assists extension of knee Nerve     Superior gluteal          Â
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