Changes

Jump to navigation Jump to search
Line 308: Line 308:       −
'''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
Line 323: Line 325:  
::::::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'''===

Navigation menu