The object of this study has been to develop a quantitative description of the mobility of the human torso, including the shoulder girdle, neck, thoracic and lumbar vertebral column, and pelvis. This has been accomplished by a systematic multidisciplinary investigation involving techniques of cadaver dissection and measurement, utilizing cineradiofluoroscopy for joint center of rotation location, anthropometry, radiography, and photogrammetry for selected positions and motions of living subjects, and computer analysis. Positional and dimensional data were obtained for 72 anthropometric dimensions on 28 living male subjects statistically representative of the 1967 USAF anthropometric survey of 3542 rated officers, including bone lengths of the extremities and vertebral landmarks. Normal excursion of these limbs was measured in the living, utilizing the landmarks established in initial cadaver dissection. Centers of joint rotation (link and positions) for the torso and limbs, lengths of functional torso links, and link excursions were correlated with linear body dimensions and landmarks obtained in traditional anthropometry. Some 35 positions for each subject were analyzed utilizing an off-line data coder system to determine how arm position affects the three-space surface coordinates. Three simultaneous regression equations were used to develop predictive models for torso positions referenced to a sitting or standing position or task.
The major results of the study are prediction equations and graphs describing how the base of the spine reference point (fifth lumbar spinal marker) moves in relation to defined seated and standing reference points for given reaches, and the development of techniques by which the lengths and excursions of torso and limb links may be estimated and located. It was found that the surface landmarks selected could predict precise location of the underlying anatomical landmarks. The results of this study provide initial basic data regarding human torso motion, joint center of motion, and link relationships.