Characteristics of Dynamic Cervical Vertebral Kinematics for Female and Male Volunteers in Low‐speed Rear Impact, based on Quasi‐static Neck Kinematics

The purpose of this study is to clarify the dynamic characteristics of inertia‐induced cervical vertebral kinematics for both female and male volunteers in low‐speed rear impact conditions by comparing quasi‐static muscle‐induced neck kinematics. Two series of volunteer tests were used. One is data from a rear impact sled test series with 2 females and 4 males. The second set of data is from a voluntary neck bending test series with 4 females and 9 males. Cervical vertebral motions were measured by a cineradiography system. The same volunteers in the first test series also participated in the second test series. C4/C5 through C6/C7 showed larger extension angle in the peak S shape than maximum voluntary retraction for females. In contrast, the peak S shape was in the maximum voluntary retraction for males. The rearward displacements at C6/C7 in the peak S shape exceeded the maximum voluntary extension for females. The vertebral angular displacement at C5/C6 was greatest in the peak extension and exceeded the voluntary extension, especially for females. The vertebral normalised displacements in X‐direction at C5/C6 and C6/C7 showed larger rearward displacements in the peak extension than the voluntary extension, and exceeded the maximum voluntary extension for both genders