In order to inquire the biomechanical behaviour of a column undergoing elastic deformation, A mathematical model was first developed. In this paper the reaction of the intervertebral discs to torsion was investigated as a function of two parameters, disc location in the spine and age. The physical quantity describing the disc response to a torque moment M_t is represented by the G module of rigidity to torsion, which qualitatively expresses the resilience of the annulus fibrosus to twist. The values of G referred to a infancy spine model (0-8 yrs) were assessed, It was determined that the G values are roughly 1/3 of those calculated in adult life and that the ratios between the G modules of two consecutive discs, compared with adulthood, are not modified.