This study was conducted to determine the external and internal biomechanical responses of the one, three and six year old pediatric cervical spine structures under varying severities of combined compression-flexion and compression-extension, and axial tension load vectors. Our existing one, three and six year old pediatric lower cervical spine finite element models were used. The models in the three age groups were developed by incorporating the characteristic developmental pediatric anatomy such as the variations in the ossification patterns. The following components were included:​ vertebral centrum, neural arches, neuro-central and costal cartilages, growth plates, nucleus pulposus, anulus fibers, ground substance and all major ligaments. The three-dimensional models were exercised using the principles of geometrical and material nonlinear analyses. The resulting external and internal biomechanical responses were expressed in terms of the overall flexibilities;​ the intrinsic stresses in the bone and intervertebral anulus, and pressures in the nucleus and facet joints were determined under each load vector. All these output were compared with respect to the adult human spine. In general, decreases in the flexibilities were apparent with increasing age;​ this was independent of the load vector. However, the magnitudes of the decrease were nonuniform with respect to the age group, and the type and severity of the external load vector. Under tension, the intrinsic pressures in the joints decreased. Under combined compression-flexion and compression-extension loading, facet joint pressures were higher than disc pressures. The relative magnitudes of the pressures were dependent on the severity of the combined load vector. The anulus stresses, in general, were highest for the adult spine with the maximum magnitudes occurring at the most severe compression-flexion and compression-extension load vectors. The stresses generally decreased from the adult spine to the one year old pediatric spine. These characteristic differences with respect to the age and loading mode may assist to explain the intrinsic load sharing among the developing pediatric components and provide a likely explanation for the mechanisms of injury.