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Quadrupedal Mechanics - Anatomy & Physiology (view source)
Revision as of 00:51, 20 June 2013
, 00:51, 20 June 2013→The lubrication of joints: multigrade specification
==='''The lubrication of joints: multigrade specification'''===
==='''The lubrication of joints: multigrade specification'''===
[[File:QMFig 3.6.png|thumb|'''Fig.3.6 The largest sesamoid bone''']]
The lubrication fluid of bursae, synovial sheaths and joints is secreted from protrusions of synovial membrane, synovial villi, located in loose parts of the joint capsule away from any compressed surfaces. This is synovial fluid. In a normal synovial sac, only a small amount of fluid is present. The viscosity of this clear or pale yellow liquid is more during slow movement, which is when the rate of shear is low. But when the shear rates are highest, the viscosity becomes much lower. The fluid drag and hence the supporting ability of the joint is therefore greatest when the limb is quietly bearing weight; the impedance is conveniently reduced for fast movements.
The lubrication fluid of bursae, synovial sheaths and joints is secreted from protrusions of synovial membrane, synovial villi, located in loose parts of the joint capsule away from any compressed surfaces. This is synovial fluid. In a normal synovial sac, only a small amount of fluid is present. The viscosity of this clear or pale yellow liquid is more during slow movement, which is when the rate of shear is low. But when the shear rates are highest, the viscosity becomes much lower. The fluid drag and hence the supporting ability of the joint is therefore greatest when the limb is quietly bearing weight; the impedance is conveniently reduced for fast movements.
:::::'''3.6 The largest sesamoid bone'''
:::::'''Fig.3.6 The largest sesamoid bone'''
:::::The patella (b) is interposed in the tendon of insertion of the quadriceps muscles (a), that insert on the tibial tuberosity through the patellar ligament (c). The patella is held in place by collateral femoropatellar ligaments (d), and the hinge movement of the joint is maintained by the collateral femorocrural ligaments (e).
:::::The patella (b) is interposed in the tendon of insertion of the quadriceps muscles (a), that insert on the tibial tuberosity through the patellar ligament (c). The patella is held in place by collateral femoropatellar ligaments (d), and the hinge movement of the joint is maintained by the collateral femorocrural ligaments (e).
==='''The resistance of joint surfaces to wear'''===
==='''The resistance of joint surfaces to wear'''===