Biomechanical Properties of the Human Neck in Lateral Flexion 751156

Properties of the human neck which may influence a person's susceptibility to “whiplash” injury during lateral impact have been studied in 96 normal subjects. Subjects were chosen on the basis of age, sex, and stature and data were grouped into six primary categories based on sex (F, M) and age (18-24, 35-44, 62-74). The data include: measures of head, neck and body anthropometry in standing and simulated automotive seating positions, three-dimensional range of motion of the head and neck, head/neck response to low-level acceleration, and both stretch reflex time and voluntary isometric muscle force in the lateral direction. Reflex times are found to vary from about 30 to 70 ms with young and middle aged persons having faster times than older persons, and females having faster times than males. Muscle strength decreases with age and males are, on the average, stronger than females. Range of motion was determined by using three-dimensional photogrammetry to compute Euler angles relative to the Frankfort plane. Ranges of motion are reported for 6 planar movements (flexion, extension, left and right rotation, left and right lateral bend) and 3 combination movements (left rotation plus flexion, left rotation plus left lateral bend, and right rotation plus extension) chosen to simulate typical lateral impact conditions. For the young subjects, ranges of motion for males and females are similar. In all cases the range of motion decreases with age, with the rate of decrease for males being greater than that for females. Data are presented in a format applicable to biomechanical modeling of the seated human occupant.

NOTE: This research was sponsored by the Insurance Institute for Highway Safety, Washington, D. C.