- The knee is a joint which has three parts. The thigh bone (the femur) meets the large shin bone (the tibia) to form the main knee joint. This joint has an inner (medial) and an outer (lateral) compartment. The kneecap (the patella) joins the femur to form a third joint, called the patellofemoral joint. The patella protects the front of the knee joint. The knee joint is surrounded by a joint capsule with ligaments strapping the inside and outside of the joint (collateral ligaments) as well as crossing within the joint (cruciate ligaments). The collateral ligaments run along the sides of the knee and limit the sideways motion of the knee. The anterior cruciate ligament (ACL) connects the tibia to the femur at the center of the knee and functions to limit rotation and forward motion of the tibia. The posterior cruciate ligament (PCL) located just behind the ACL limits the backward motion of the tibia. All of these ligaments provide stability and strength to the knee joint. The meniscus is a thickened cartilage pad between the two joints formed by the femur and tibia. The meniscus acts as a smooth surface for the joint to move on. The knee joint is surrounded by fluid- filled sacs called bursae, which serve as gliding surfaces that reduce friction of the tendons. Below the kneecap, there is a large tendon (patellar tendon) which attaches to the front of the tibia bone. There are large blood vessels passing through the area behind the knee (referred to as the popliteal space). The large muscles of the thigh move the knee. In the front of the thigh the quadriceps muscles extend the knee joint. In the back of the thigh, the hamstring muscles flex the knee. The knee also rotates slightly under guidance of specific muscles of the thigh. The knee functions to allow movement of the leg and is critical to normal walking. The knee flexes normally to a maximum of 135 degrees and extends to 0 degrees. The bursae, or fluid-filled sacs, serve as gliding surfaces for the tendons to reduce the force of friction as these tendons move. The knee is a weight-bearing joint. Each meniscus serves to evenly load the surface during weight- bearing and also adds in disbursing joint fluid for joint lubrication.
* * *- housemaid's k. an adventitious occupational bursitis occurring over the area of contact when kneeling; not to be confused with infrapatellar bursitis. SYN: prepatellar bursitis.- locked k. a condition in which the k. lacks full extension and flexion because of internal derangement, usually the result of a torn meniscus.- runner's k. an overuse syndrome of anterior k. pain associated with excessive lateral motion of the patella during activity. SYN: patellofemoral stress syndrome.- Wilbrand k. bundle of inferior nasal optic nerve fibers subserving the superior temporal visual field and crossing in the anterior optic chiasm, briefly entering the contralateral posterior optic nerve [CN II] before proceeding into the contralateral optic tract. Recent research indicates that this may be an artifact of retinal degeneration and not present in the normal anatomy.
* * *knee 'nē n1 a) a joint in the middle part of the human leg that is the articulation between the femur, tibia, and patella called also knee jointb) the part of the leg that includes this joint2 a) the joint in the hind leg of a 4-footed vertebrate that corresponds to the human kneeb) the carpal joint of the foreleg of a 4-footed vertebratekneed 'nēd adj
* * *n.the hinge joint (see ginglymus) between the end of the femur, the top of the tibia, and the back of the patella (kneecap). It is commonly involved in sports injury (such as a torn meniscus or ligament) and is a common site of osteoarthritis and rheumatoid arthritis; it can be replaced by an artificial joint (see also arthroplasty).
* * *(ne) 1. genu (def. 1). 2. any structure bent like the knee. 3. in ungulates, the carpus of the foreleg or the stifle joint of the hind leg.
Medical dictionary. 2011.