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A plane joint (arthrodial joint, gliding joint, plane articulation) is a synovial joint which, under physiological conditions, allows only gliding movement. Plane joints permit sliding movements in the plane of articular surfaces. The opposed surfaces of the bones are flat or almost flat, with movement limited by their tight joint capsules.
This joint unites long bones and permits free bone movement and greater mobility. [1] The synovial cavity/joint is filled with synovial fluid. The joint capsule is made up of an outer layer of fibrous membrane, which keeps the bones together structurally, and an inner layer, the synovial membrane, which seals in the synovial fluid.
Synovial fluid is an ultrafiltrate from blood, and contains proteins derived from the blood plasma and proteins that are produced by cells within the joint tissues. [4] The fluid contains hyaluronan secreted by fibroblast-like cells in the synovial membrane, lubricin (proteoglycan 4; PRG4 ) secreted by the surface chondrocytes of the articular ...
The fibroblast-like synoviocytes (derived from mesenchyme) [3] manufacture a long-chain sugar polymer called hyaluronan (hence rich in endoplasmic reticulum); which makes the synovial fluid "ropy"-like egg-white, together with a molecule called lubricin, which lubricates the joint surfaces. The water of synovial fluid is not secreted as such ...
A subcutaneous bursa is located between the skin and an underlying bone. It allows skin to move smoothly over the bone. Examples include the prepatellar bursa located over the kneecap and the olecranon bursa at the tip of the elbow. A submuscular bursa is found between a muscle and an underlying bone, or between adjacent muscles.
Bone marrow produces blood cells in a process called hematopoiesis. [53] Blood cells that are created in bone marrow include red blood cells, platelets and white blood cells. [54] Progenitor cells such as the hematopoietic stem cell divide in a process called mitosis to produce precursor cells. These include precursors which eventually give ...
The red marrow of some bones is an important site for blood cell production, approximately 2.6 million red blood cells per second in order to replace existing cells that have been destroyed by the liver. [4] Here all erythrocytes, platelets, and most leukocytes form in adults. From the red marrow, erythrocytes, platelets, and leukocytes migrate ...
The acromioclavicular joint provides the ability to raise the arm above the head. This joint functions as a pivot point (although technically it is a gliding synovial joint), acting like a strut to help with movement of the scapula resulting in a greater degree of arm rotation.