Meniscus

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meniscus

1. the curved upper surface of a liquid standing in a tube, produced by the surface tension
2. a crescent-shaped fibrous cartilage between the bones at certain joints, esp at the knee
3. a crescent-shaped lens; a concavo-convex or convexo-concave lens

Meniscus

 

the crescent-shaped inner and outer intraarticular cartilages in the knee joint.

The menisci increase the congruence of the joint surfaces, making diversity of movement possible and softening the effect of impact. The menisci may be injured by forced movement connected with overextension of the joint (most often in athletes). When the menisci are detached, there is a sudden block of the joint; sharp pains result from strangulation of the detached parts and the impossibility of movement in the joint. Proper treatment (conservative or, when this proves unsuccessful, surgical) completely restores joint function. In other joints (for example, mandibular and radiocarpal) intraarticular cartilages with analagous functions are called disks.


Meniscus

 

in optics, a concavo-convex or convexo-concave lens bounded by two spherical surfaces; such a lens is one of the most widely used types of lenses. A meniscus whose thickness is greater at the center than at the edges (positive meniscus) is a converging lens, and a meniscus whose thickness is greater at the edges than at the center (negative meniscus) is a diverging lens. Menisci are used in various optical systems, for example, in eyeglasses, in the objectives of motion-picture cameras and still cameras, and as attachment lenses that change the focal lengths of objectives.

Meniscus systems have gained widespread use in applications that require a higher degree of correspondence between the optical image and the object, for example, in astronomy. In these systems, small distortions of the image introduced by the meniscus (aberrations) are compensated by aberrations introduced by other elements of the system. The result is that it is possible to obtain practically undistorted images. The inherent aberrations of the individual menisci may be reduced by the use of diaphragms (for example, in camera objectives, up to a relative aperture of 1:11).


Meniscus

 

the curved free surface of a liquid near the contact between the liquid and the surface of a solid. For example, a meniscus is formed at the walls of vessels and in the channels and pores of spongy materials impregnated with liquids. A meniscus has a spherical shape in thin (capillary) tubes and a cylindrical shape in a sufficiently narrow gap between flat plates. The curvature of the meniscus is determined by the relationship between the forces of molecular interaction at the triple point of the three phases—solid, liquid, and gas (or vapor). A liquid that wets a given surface forms a concave meniscus, whereas a liquid that does not wet the surface forms a convex meniscus. In the first case, the mutual attraction between the molecules of the liquid (cohesion) is weaker than the attraction of the molecules of the liquid by the molecules of the surface of the solid (adhesion). Conversely, in the second case, the forces of cohesion exceed the forces of adhesion. The vapor pressure over a concave meniscus is less than, and that over a convex meniscus is more than, the vapor pressure over a plane liquid surface. This explains such phenomena as capillary condensation, capillary absorption of a liquid in porous and fibrous materials, and the rising and falling of liquids in thin pipes.

meniscus

[mə′nis·kəs]
(anatomy)
A crescent-shaped body, especially an interarticular cartilage.
(fluid mechanics)
The free surface of a liquid which is near the walls of a vessel and which is curved because of surface tension.
(metallurgy)
In reference to a solder joint, the minimum angle at which the solder tapers from the joint to the flat area.
References in periodicals archive ?
42% of the players; 32 were medial meniscus tears and 20 were lateral meniscus tears.
There is concern that a small meniscus tear can become larger if left untreated; this would be dependent on the nature of the tear.
MRI is a good choice of imaging modality and has good sensitivity and specificity for diagnosis of meniscus tears.
However, as only the 5-13% of the meniscus tear cases can be diagnosed among non-symptomatic individuals through MRI [16, 17].
This study, as well as previous research, did not look at surgery for an acute medial meniscus tear following a traumatic incident, such as a fall or direct blow.
The EVERY idea of the long rehabilitation period required after a knee surgery led Dr Priyadarshi Jitender Kumar to choose an arthroscopy instead, after he suffered a meniscus tear in his right knee.
Over t next few weeks tried to train through it, we thought it was just a meniscus tear.
Multiple reports show that 10-20 years after their ACL or meniscus tear, every second patient has OA, often with significant pain, functional limitations, and diminished quality of life (Arthritis Rheum.
One of the hallmarks of an ACL or meniscus tear is its limiting effect on an athlete's lateral movement.
The doctor's initial diagnosis also indicated a possible meniscus tear, prompting Monica Droughn to schedule an MRI.
The world No 2, at the start of the day the only one of the top three seeds left in the draw, spent most of Sunday unable to practise, receiving injections and contemplating pulling out after a meniscus tear in her knee impaired her usually remarkable mobility.
But during her senior year of high school, Rea had knee surgery to clean out cartilage from a possible meniscus tear.