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Diagram:
http://en.wikipedia.org/wiki/Image:Knee_diagram.png
http://en.wikipedia.org/wiki/Image:Gray351.png
http://en.wikipedia.org/wiki/Image:Gray348.png
膝,俗稱膝蓋,為位于大小腿之间的连接部位。膝的主要内部组成结构为半月板以及四条韧带。
半月板为膝内部股骨下端和胫骨上端之间的接连处所垫的一块新月形的纤维软骨组织,作用是缓冲膝关节的震动,以及避免两块骨头的直接摩擦。
另外,它由四条主要的韧带支撑着。其中有两条在膝的两侧,称为中侧突韧带和外侧突韧带,主要功能是防止膝部轴离位;另外两条韧带则分别分布在膝前后方,称为前十字韧带和后十字韧带,作用是防止膝部前后移位。
KNEE
In human anatomy, the knee is the lower extremity joint connecting the femur and the tibia. Since in humans the knee supports nearly the entire weight of the body, is the most vulnerable both to acute injury and to the development of osteoarthritis.
Contents
1 Function of the knee
2 Human anatomy
2.1 Ligaments
2.2 Menisci
2.3 Movements
2.4 Injury
3 Animal anatomy
4 Trivia
5 See also
6 Additional images
7 External links
Function of the knee
The knee functions as a living, self-maintaining, biologic transmission, the purpose of which is to accept and transfer biomechanical loads between the femur, tibia, patella, and fibula. In this analogy the ligaments represent non-rigid adaptable sensate linkages within the biologic transmission. The articular cartilages act as bearing surfaces, and the menisci as mobile bearings. The muscles function as living cellular engines that in concentric contraction provide motive forces across the joint, and in eccentric contraction act as brakes and dampening systems, absorbing loads.
Human anatomy
The knee is a complex, compound, condyloid variety of a synovial joint which hovers. It actually comprises two separate joints.
The femoro-patellar joint consists of the patella, or "kneecap", a so-called sesamoid bone which sits within the tendon of the anterior thigh muscle (m. quadriceps femoris), and the patellar groove on the front of the femur through which it slides.
The femoro-tibial joint links the femur, or thigh bone, with the tibia, the main bone of the (lower) leg. The joint is bathed in a viscous (synovial) fluid which is contained inside the "synovial" membrane, or joint capsule.
The recess behind the knee is called the popliteal fossa.
Menisci
These are cartilaginous elements within the knee joint which serve to protect the ends of the bones from rubbing on each other and to effectively deepen the tibial sockets into which the femur attaches. They also play a role in shock absorption. There are two menisci in each knee, the medial meniscus and the lateral meniscus. Either or both may be cracked, or torn, when the knee is forcefully rotated and/or bent.
Movements
The knee permits the following movements: flexion, extension, as well as slight medial and lateral rotation. Also, the knee has special locking and unlocking mechanisms, related to movement by the femoral condyles on the tibial plateau. The ligaments and menisci, along with the muscles which traverse the joint, prevent movement beyond the knee's intended range of motion. It is also classified as a hinge joint.
The range of movement is as follows: Flexion is permitted up to 120º when the hip is extended, 140º when the hip is flexed and 160º when the knee is flexed passively. Medial rotation is limited to 10º and lateral rotation to 30º .