Tensile neck injuries are amongst the m ost serious cervical injuries. Recent advancem ents in autom otive safety devices, while enhancing overall safety, have increased the im portance of tensile neck injury. U nfortunately however, neither reliable hum an cervical tensile tolerance d a ta nor tensile structural d a ta is currently available. The purpose of this study is to provide previously unavailable kinetic and tolerance d ata of the ligamentous cervical spine and determ ine the effect of neck muscle on tensile load response and tolerance. Six male hum an cadaver specimens were used. Isolated ligamentous cervical spine tests (Occiput - T l) were used to quantify the significant differences in kinetics due to head end condition and anteroposterior eccentricity of the tensile load. The spine was then separated into m otion segments for tension-extension failure testing. The upper cervical spine tolerance of 2400 ± 270 N (Occiput-C2) was found to be significantly greater than the lower cervical spine tolerance of 1780 ± 230 N (C4-C5 and C6-C7 segments). D ata from these experim ents were used to develop and validate a com putational model of the ligamentous spine. The model predicted the end condition and eccentricity responses w ith an average RMS error 9.0% of full scale for the tensile force-displacement relationship. Cervical muscular geometry d a ta derived from cadaver dissection and MRI imaging were used to incorporate a muscular response to the ligam entous spine model. The cervical m usculature under m axim al stim ulation was found to increase the tolerance of the cervical spine from 1800 N to 4160 N. In addition, the cervical m usculature offered the lower cervical spine greater protection from tensile injury by carrying a larger percentage of the tensile load in the lower spine th an in the upper spine. This resulted in a predicted shift in the site of injury from the lower cervical spine to the upper cervical spine and offers an explanation of the mechanism of upper cervical spine tension injuries observed clinically. The results from this study have lim ited the range of tensile tolerance from 1.1-6.2 kN to 1.8-4.16 kN. More im portantly, this range in the tensile tolerance is now understood and can be attributed to the varying role of the cervical musculature.