AskDefine | Define knee

Dictionary Definition

knee

Noun

1 hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella [syn: knee joint, articulatio genus, genu]
2 joint between the femur and tibia in a quadruped; corresponds to the human knee [syn: stifle]
3 cloth covering consisting of the part of a trouser leg that covers the knee

User Contributed Dictionary

English

Etymology

etyl ang cneo, from , from

Pronunciation

Homophones

Noun

  1. In humans, the joint in the middle part of the leg.
    Jessica was wearing shorts, so she skinned her exposed knees when she fell.
  2. The joint, or region of the joint, between the thigh and leg.
  3. In the horse and allied animals, the carpal joint, corresponding to the wrist in humans.
  4. (shipbuilding) A piece of timber or metal formed with an angle somewhat in the shape of the human knee when bent.
    • 1980, Richard W. Unger, The Ship in the Medieval Economy 600-1600, page 41
      Deck beams were supported by hanging knees, triangular pieces of wood typically found underneath the timbers they are designed to support, but in this case found above them.
  5. An act of kneeling, especially to show respect or courtesy.
    Give them title, knee, and approbation. Shak.
    To make a knee.
  6. Any knee-shaped item or sharp angle in a line, "the knee of a graph", an inflection point

Translations

Verb

  1. transitive archaic to kneel to
    • 1605: I could as well be brought / To knee his throne and, squire-like, pension beg / To keep base life afoot. — William Shakespeare, King Lear II.ii
  2. poke or strike with the knee

Extensive Definition

The knee is the lower extremity joint connecting the femur, fibula, patella, and the tibia. Since in humans the knee supports nearly the entire weight of the body, it is the joint most vulnerable both to acute injury and the development of osteoarthritis.

Human anatomy

Upon birth, a baby will not have a conventional knee cap, but a growth formed of cartilage. In human females this turns to a normal bone knee cap by the age of 3, in males the age of 5.
The knee is a complex, compound, condyloid variety of a synovial joint which hovers. It actually comprises two separate joints.
  • 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. It can also be called a "knee pit."

Ligaments

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 .

Blood supply

The femoral artery and the popliteal artery help form the arterial network surrounding the knee joint (articular rete). There are 6 main branches:
The medial genicular arteries penetrate the knee joint

Injury

In sports that place great pressure on the knees, especially with twisting forces, it is common to tear one or more ligaments or cartilages. An increasingly common victim to injury is the anterior cruciate ligament, often torn as a result of a rapid direction change while running or some other, violent twisting motion. It can also be torn by extending the knee forcefully beyond its normal range. In some such cases, other structures incur damage as well. Especially debilitating is the unfortunately common "unhappy triad" of torn medial collateral and anterior cruciate ligaments and a torn medial meniscus. This typically arises from a combination of inwards forcing and twisting.
Before the advent of arthroscopy and arthroscopic surgery, patients having surgery for a torn ACL required at least nine months of rehabilitation. With current techniques, such patients may be walking without crutches in two weeks, and playing some sports in but a few months. In Australian rules football, knee injuries are among the most common, especially in ruck contests, involving the crashing of two knees during the leap. These injuries forced new rule changes for the 2005 season.
In addition to developing new surgical procedures, ongoing research is looking into underlying problems which may increase the likelihood of an athlete suffering a severe knee injury. These findings may lead to effective preventive measures, especially in female athletes, who have been shown to be especially vulnerable to ACL tears from relatively minor trauma. Techniques to minimize the risk of an ACL injury while skiing are published by Vermont Safety Research

Diagnosis

Several diagnostic maneuvers help clinicians diagnose an injured ACL. In the anterior drawer test, the examiner applies an anterior force on the proximal tibia with the knee in 90 degrees of flexion. The Lachman test is similar, but performed with the knee in only about twenty degrees of flexion, while the pivot-shift test adds a valgus (outside-in) force to the knee while it is moved from flexion to extension. Any abnormal motion in these maneuvers suggests a tear.
The diagnosis is usually confirmed by MRI, the availability of which has greatly lessened the number of purely diagnostic arthroscopies performed.

Animal anatomy

In humans the knee refers to the joints between the femur, tibia and patella. In quadrupeds, particularly horses and ungulates the term is commonly used to refer to the carpus, probably because of its similar hinge or ginglymus action. The joints between the femur, tibia and patella are known as the stifle in quadrupeds. In insects and other animals the term knee is used widely to refer to any ginglymus joint.

Additional images

Image:Knie ct.gif|Knee MR Image:Knie mr.jpg|Knee MR Image:Knie-roentgen-r-seite.jpg|Knee X-ray Image:Legamenti crociati.jpg|Cruciate ligaments Image:Knee.female.jpg|Female knee Image:Male Knee by David Shankbone.jpg|Male knee

References

knee in Arabic: ركبة
knee in Aymara: Qunquri
knee in Catalan: Genoll
knee in Czech: Koleno
knee in Pennsylvania German: Gnie
knee in German: Kniegelenk
knee in Spanish: Rodilla
knee in Esperanto: Genuo
knee in French: Genou
knee in Korean: 무릎
knee in Indonesian: Lutut
knee in Italian: Ginocchio
knee in Hebrew: ברך
knee in Latin: Genu
knee in Latvian: Ceļa locītava
knee in Lithuanian: Kelis
knee in Dutch: Knie
knee in Japanese: 膝
knee in Norwegian: Kne
knee in Occitan (post 1500): Genolh
knee in Pangasinan: Pueg
knee in Polish: Staw kolanowy
knee in Portuguese: Joelho
knee in Russian: Колено (анатомия)
knee in Sicilian: Dinocchiu
knee in Simple English: Knee
knee in Slovenian: Koleno
knee in Finnish: Polvinivel
knee in Swedish: Knä
knee in Tagalog: Tuhod
knee in Turkish: Diz
knee in Võro: Põlv
knee in Chinese: 膝

Synonyms, Antonyms and Related Words

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