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Quadrupedal Mechanics - Anatomy & Physiology (view source)
Revision as of 00:46, 20 June 2013
, 00:46, 20 June 2013→The role of tendons
'''Antifriction devices associated with tendons'''
==='''Antifriction devices associated with tendons'''===
[[File:QMFig 3.5.png|thumb|'''Fig.3.5 Structures reducing friction between tendon and bone''']]
Limbs are, of course, not straight, and the angles of joints can change markedly. Tendons allow the transmission of a force round these angles. The simplest way to smooth their passage is to provide a cushion. This is a bursa (Latin, wine sac made of goatskin), a pouch lined by synovial membrane and filled with synovial fluid. This lies between the tendon and the bone (Fig. 3.5 a), or it may wrap around the tendon to form a synovial sheath (Fig. 3.5 b). Sheaths are often held in place by transversely arranged collagenous structures, retinacula. A further adaptation occurs when the surface of the bone becomes changed to articular cartilage and forms one boundary of the bursal cavity. A pulley-like arrangement is formed (Fig 3.5 c).
Limbs are, of course, not straight, and the angles of joints can change markedly. Tendons allow the transmission of a force round these angles. The simplest way to smooth their passage is to provide a cushion. This is a bursa (Latin, wine sac made of goatskin), a pouch lined by synovial membrane and filled with synovial fluid. This lies between the tendon and the bone (Fig. 3.5 a), or it may wrap around the tendon to form a synovial sheath (Fig. 3.5 b). Sheaths are often held in place by transversely arranged collagenous structures, retinacula. A further adaptation occurs when the surface of the bone becomes changed to articular cartilage and forms one boundary of the bursal cavity. A pulley-like arrangement is formed (Fig 3.5 c).
:::::'''3.5 Structures reducing friction between tendon and bone'''
:::::'''Fig.3.5 Structures reducing friction between tendon and bone'''
:::::(a) to (d) represent increasing complexity
:::::(a) to (d) represent increasing complexity
::::::c. articular cartilage, bursa and retinaculum
::::::c. articular cartilage, bursa and retinaculum
::::::d. sesamoid bone, articular cartilage, synovial joint and collateral sesamoid ligaments
::::::d. sesamoid bone, articular cartilage, synovial joint and collateral sesamoid ligaments
==='''Shearing within tendons'''===
==='''Shearing within tendons'''===