RESUMO
Background: The articular processes of thoracolumbar vertebral column play an important role in weight transmission and determining the range and direction of movements between any two vertebrae. Size of these facets has been correlated with the magnitude of stress imposed on them. Purpose of study: The present study has been conducted on the articular processes of 510 vertebrae (thoracic: 360; lumbar:150) with the aim to provide high quality data sets for constructing the models of spine to study mechanics of spinal instrumentation. The length , width and the distance between the right & left superior & inferior articular processes have been measured with the vernier callipers. The presence/ absence of mamillary tubercle has been observed in the present study. Results: The length of thoracic SAFs was almost same at all levels whereas that of the lumbar SAFs increased gradually from L1-L5. However the width showed a variable trend. In case of thoracic IAFs both these parameters showed a variable trend. Whereas in lumbar region, these increased gradually from L1-L5. The distance between two inferior articular processes was more than that between two superior articular processes at almost all levels except T1-T3 & L1-L4 where reverse was true. The mamillary tubercle/process was altogether absent from T-1 to T-8. From T-9 to T-11, the number of vertebral column showing mamillary tubercle increased from 4-19. However at T-12, it was seen in 29 Vertebral columns. In lumbar region, it was well developed in all vertebrae and termed as mamillary process. Conclusion: The measurements obtained by present study reveals the importance of articular facets in understanding basic spinal mechanics and its application with respect to weight transmission.