Meniscus (anatomy)
Encyclopedia
In anatomy
, a meniscus (from Greek
μηνίσκος meniskos, "crescent") is a crescent-shaped fibrocartilaginous
structure that, in contrast to articular disk
s, only partly divides a joint cavity. In human
s it is present in the knee
, acromioclavicular
, sternoclavicular, and temporomandibular joint
s; in other organisms they may be present in other joints (e.g. between the forearm
bones of bird
s). A small meniscus also occurs in the radio-carpal joint.
It usually refers to either of two specific parts of cartilage
of the knee: The lateral
and medial menisci
. Both are cartilaginous tissues that provide structural integrity to the knee when it undergoes tension
and torsion
. The menisci are also known as 'semi-lunar' cartilages — referring to their half-moon "C" shape — a term which has been largely dropped by the medical profession, but which led to the menisci being called knee 'cartilages' by the lay public.
joint between the lower leg (tibia
) and the thigh (femur
). They are shaped concave on the top and flat on the bottom, articulating with the tibia. They are attached to the small depressions (fossa
e) between the condyles of the tibia (intercondyloid fossa), and towards the center they are unattached and their shape narrows to a thin shelf.
and extension), the menisci spread the load of the body's weight. This differs from sesamoid bone
s, which are made of osseous tissue
and whose function primarily is to protect the nearby tendon and to increase its mechanical effect.
s and orthopedics
, people will sometimes speak of "torn cartilage" and actually be referring to an injury to one of the menisci.
The Unhappy Triad
is a set of commonly co-occurring knee injuries which includes injury to the medial meniscus.
Two surgeries are most common of the meniscus. Depending on location, age, and doctor's preference, people usually either repair it or remove a part or all of it (meniscectomy). Each has its advantages and disadvantages.
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
, a meniscus (from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
μηνίσκος meniskos, "crescent") is a crescent-shaped fibrocartilaginous
Fibrocartilage
White fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its flexibility and toughness to the former of these constituents, and its elasticity to the latter...
structure that, in contrast to articular disk
Articular disk
The articular disk is a thin, oval plate of fibrocartilage present in several joints which separates synovial cavities. This separation of the cavity space allows for separate movements to occur in each space....
s, only partly divides a joint cavity. In human
Human
Humans are the only living species in the Homo genus...
s it is present in the knee
Knee
The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...
, acromioclavicular
Acromioclavicular joint
The acromioclavicular joint, or AC joint, is a joint at the top of the shoulder. It is the junction between the acromion and the clavicle. -Function:...
, sternoclavicular, and temporomandibular joint
Temporomandibular joint
The temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. There are two TMJs, one on either side, working in unison. The name is derived from the two bones which form the joint: the upper temporal bone which is part of the cranium , and the lower jaw bone called the...
s; in other organisms they may be present in other joints (e.g. between the forearm
Forearm
-See also:*Forearm flexors*Forearm muscles...
bones of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s). A small meniscus also occurs in the radio-carpal joint.
It usually refers to either of two specific parts of cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
of the knee: The lateral
Lateral meniscus
The lateral meniscus, also called the external semilunar fibrocartilage, is a fibrocartilaginous band that spans the lateral side of the interior of the knee joint. It is one of two menisci of the knee, the other being the medial meniscus. It is nearly circular and covers a larger portion of the...
and medial menisci
Medial meniscus
-External links: *...
. Both are cartilaginous tissues that provide structural integrity to the knee when it undergoes tension
Tension (mechanics)
In physics, tension is the magnitude of the pulling force exerted by a string, cable, chain, or similar object on another object. It is the opposite of compression. As tension is the magnitude of a force, it is measured in newtons and is always measured parallel to the string on which it applies...
and torsion
Torsion (mechanics)
In solid mechanics, torsion is the twisting of an object due to an applied torque. In sections perpendicular to the torque axis, the resultant shear stress in this section is perpendicular to the radius....
. The menisci are also known as 'semi-lunar' cartilages — referring to their half-moon "C" shape — a term which has been largely dropped by the medical profession, but which led to the menisci being called knee 'cartilages' by the lay public.
Anatomy
The menisci of the knee joint are two pads of cartilaginous tissue which serve to disperse friction in the kneeKnee
The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...
joint between the lower leg (tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
) and the thigh (femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
). They are shaped concave on the top and flat on the bottom, articulating with the tibia. They are attached to the small depressions (fossa
Fossa (anatomy)
In anatomical terminology, fossa has come to mean a depression or hollow, in general, in a bone. Other parts of the body may be involved, for example, the antecubital fossa...
e) between the condyles of the tibia (intercondyloid fossa), and towards the center they are unattached and their shape narrows to a thin shelf.
Function
The menisci act to disperse the weight of the body and reduce friction during movement. Since the condyles of the femur and tibia meet at one point (which changes during flexionFlexion
In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...
and extension), the menisci spread the load of the body's weight. This differs from sesamoid bone
Sesamoid bone
In anatomy, a sesamoid bone is a bone embedded within a tendon.Sesamoids are found in locations where a tendon passes over a joint, such as the hand, knee, and foot. Functionally, they act to protect the tendon and to increase its mechanical effect. The presence of the sesamoid bone holds the...
s, which are made of osseous tissue
Osseous tissue
Osseous tissue, or bone tissue, is the major structural and supportive connective tissue of the body. Osseous tissue forms the rigid part of the bone organs that make up the skeletal system.-Formation:Bone tissue is a mineralized connective tissue...
and whose function primarily is to protect the nearby tendon and to increase its mechanical effect.
Injury
In sportSport
A Sport is all forms of physical activity which, through casual or organised participation, aim to use, maintain or improve physical fitness and provide entertainment to participants. Sport may be competitive, where a winner or winners can be identified by objective means, and may require a degree...
s and orthopedics
Orthopedic surgery
Orthopedic surgery or orthopedics is the branch of surgery concerned with conditions involving the musculoskeletal system...
, people will sometimes speak of "torn cartilage" and actually be referring to an injury to one of the menisci.
The Unhappy Triad
Unhappy triad
An unhappy triad is an injury to the anterior cruciate ligament, medial collateral ligament, and the meniscus. The triad refers to a complete or partial tear of the anterior cruciate ligament, medial collateral ligament, and the meniscus...
is a set of commonly co-occurring knee injuries which includes injury to the medial meniscus.
Two surgeries are most common of the meniscus. Depending on location, age, and doctor's preference, people usually either repair it or remove a part or all of it (meniscectomy). Each has its advantages and disadvantages.
See also
- Meniscal cartilage replacement therapyMeniscal Cartilage Replacement TherapyThe meniscus is a C-shaped piece of fibrocartilage located at the peripheral aspect of the knee joint that offers lubrication and nutrition to the joint. Each knee has two menisci, medial and lateral, whose purpose is to provide space between the tibia and the femur, preventing friction and...
- Discoid meniscusDiscoid meniscusDiscoid meniscus is a rare human anatomic variant that usually affects the lateral meniscus of the knee. Usually a person with this anomaly has no complaints, however, it may present as pain, swelling, or a snapping sound heard from the affected knee...
- Anterior Cruciate LigamentAnterior cruciate ligamentThe anterior cruciate ligament is a cruciate ligament which is one of the four major ligaments of the human knee. In the quadruped stifle , based on its anatomical position, it is referred to as the cranial cruciate ligament.The ACL originates from deep within the notch of the distal femur...