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joints
anatomy
Joints are the connection points between bones. Basically there are movable joints and immovable joints. For training purpose the first category is most interesting. Movable joints are divided into the highly mobile synovial joints, such as knee or shoulder joint, and cartilaginous joints, wich allow only little movement, such as joints between sternum and ribs.
Synovial joints have a high range of motion because of a space between the articulating bones, wich is filled with synovial fluid. The contact area of each bone is covered with a layer of cartilage, wich is elastically deformable, to protect it from pressure, friction and other forces.
Cartilage belongs to the supportive structures and has no artery. That´s why it is recovering or healing very slowly. It can only be nourished and supplied with oxygen by diffusion from surrounding tissues. The premise to that is multilateral movement to have the synoval fluids exchaned, waste products removed and the cartilage filled with nutrients.
So if you have any problems in your joints, don´t put your body to rest and wait for healing. Better move with proper intensity and / or resistance.
synovial joint illustration
ligaments
Ligaments are fibrous tissues that connect bones. They are made of collagen fibers, wich makes them very tough and keeps them slightly elastic.
joint capsule
Capsules surround the complete joint and wrap it like some kind of envelope. Actually it´s two layers, the capsule itself and the synoval membrane.
synovial membrane
This membrane secretes synovial fluids. It´s a very thin tissue. The membrane also contains blood vessels, wich make it very important for the joint´s nutrient supply.
synovial fluid
Synovial fluid provides nutrients to the joint. It´s also responsible for lubrication, wich reduces friction between the opposing layers of articular cartilage.
articular cartilage
Articular cartilage is a connective tissue. It´s very dense and contains no blood vessels. Nutrient supply only works through diffusion. The smooth cartilage surface enables the articulating bones to move.
synovial joint classification
type |
illustration |
function |
examples |
Ball-and-
Socket-Joint |
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Distal bone can move around a center in an indefinite number of axes. Main movements are flexion-extension, adduction-abduction, axial rotation and circumduction. |
hips, shoulders |
Ellipsoid Joint |
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Distal bone has an ovoid articular surface and is received into an elliptical cavit, wich makes it impossible for the bones to perform axial rotation. So main movements here are flexion-extension, adduction-abduction and circumduction. |
wrist |
Hinge Joint |
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Here the distal bone can move only in one plane, flexion and extension (forward and backward). |
knee, elbow, fingers |
Flat Joint |
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The main movements are flexion-extension and rotation. |
wrist |
Saddle Joint |
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The saddle joitn consists of two opposing surfaces that are reciprocally concave-convex, wich allows flexion, extension, adduction, abduction, and circumduction, but no axial rotation. |
thumb |
Pivot Joint |
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A pivot joint´s movement is limited to rotation. |
Atlas and Axis, proximal radioulnar articulation |
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