knee - Human anatomy

Commonly used to refer to the region around the knee-cap (patella); more specifically, in anatomy, the largest joint in the human body, being the articulation between the femoral projections (condyles) and the tibial plateaux, and including the joint between the patella and the femur. It allows a wide range of movement, yet still retains a high degree of stability, because of the presence and arrangement of the ligaments of the joint. It contains the medial and lateral menisci (pieces of fibrous tissue between the femur and tibia), which help compensate for the differences in shape between the surfaces, aid in joint lubrication, and assist in weight-bearing.

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, it is vulnerable both to acute injury and to the development of osteoarthritis.

Human anatomy

The knee is a complex, compound, condyloid variety of a synovial joint which hovers. The joint is bathed in a viscous (synovial) fluid which is contained inside the "synovial" membrane, or "joint capsule".

Ligaments

The human knee is associated with the following ligaments:

anterior cruciate ligament (ACL). posterior cruciate ligament (PCL) capsular ligament ligamentum patellae medial collateral ligament (MCL a.k.a. The MCL protects the medial side of the knee from being bent open by a stress applied to the lateral side of the knee (a valgus force). oblique popliteal ligament

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. 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, locking, unlocking, and slight rotation. The ligaments and menisci, along with the muscles which traverse the joint, prevent movement beyond the knee's intended range of motion.

Injury

In sports such as wrestling, basketball, competitive swimming, American football, Australian rules football, skiing, soccer and hockey or other sports that involve great stress to the knees, it is common to tear one or more ligaments or cartilages. Especially debilitating is the unfortunately common triad of torn medial collateral and anterior cruciate ligaments and a torn medial meniscus.

Before the advent of arthroscopy and arthroscopic surgery, patients having surgery for a torn ACL required at least nine months of rehabilitation. In Australian rules football, knee injuries are among the most common, with a great deal of controversy caused in ruck contests, where the crashing of two knees during the leap has caused injuries to numerous players.

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.

In humans the knee refers to the joints between the femur, tibia and patella. In insects and other animals the term knee is used widely to refer to any ginglymus joint.