Ultrasound can provide a non-invasive quantitative tool to image acute and chronic cervical spine injury and disease. Our work demonstrates that ultrasound is able to quantify intervertebral disc(IVD) deformation of cervical spine functional spine units' at an accuracy of ±0.148 mm during applied spine motions at frequencies <6 HZ using current clinical ultrasound devices. Using clinical ultrasound, we demonstrated that when a subject wears a standard issue military helmet while performing activities such as jumping from a height, a larger fraction of the compressive impulse is transmitted to the C4-C5 and C5-C6 IVDs compared to when the individual is not wearing the helmet. © 2013 IEEE.