Meniscus


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Related to Meniscus: meniscus tear

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 ?
Horizontal cleavage tears (HCT) are degenerative tears often found in the posterior horn of the medial meniscus and are believed to be the result of shear force fatigue in older patients.
In the case of rupture of the meniscus, the period of hospitalization is 24 hours.
Discoid lateral meniscus is thicker and discoid shaped and covers greater area of the tibial plateau than normal menisci.
He'd had a transplant performed by Mr Tim Spalding at the Hospital of St Cross in Rugby to replace his worn meniscus.
Most patients with concomitant meniscus and ACL injury were in the age group from 21 to 30 years (43.
US-based orthopedics medical practice Advanced Orthopaedics has performed the first meniscus replacement procedure in Virginia using medical device maker Active Implants' NUsurface Implant, the company said.
When you hear about a professional athlete having surgery for a cartilage tear in his knee, this usually refers to a meniscus injury.
The knee meniscus is a piece of cartilage between the leg bones that cushions and stabilizes the joint, protecting the bones from wear and tear.
Radiographs of his left knee showed lateral-dominant osteoarthritis (Figure 1), and MRI showed that the posterior portion of the lateral meniscus was torn (Figure 2).
A statement from Chelsea read: "Thibaut Courtois underwent surgery yesterday (Thursday) on an avulsion of the posterior corner and medial part of the internal meniscus of his right knee.
The knee joint consists of three articulations in one: two condyloid joints, one between each condyle of the femur and the corresponding meniscus and condyle of the tibia; and a third between the patella and the femur.