Control of positioning the cervical spine and its application to measuring extensor strength.

The great variability of the flexion of the cervical spine renders an exact description of the control of various positions difficult. A method was developed enabling a precise control of positioning the cervical spine and head in the sagittal plane. In three repeated measurements the mean values of the position of external anatomical landmarks and distances between them exhibited a good reproducibility. Any variable effect of gravity on the activity of the neck muscles at different positions of the cervical spine was eliminated by the passive compensation of gravity. The significance of methodical details is illustrated by the results of an applied study. The maximum strength of neck extensors was examined in 12 male subjects in a supine position at four different flexion angles from 0 to 30 degrees of the cervical spine. The vertical force component was measured. The maximum voluntary moments of forces about the bilateral motion axis of the C7T1 motion segment exhibited a tendency to decrease with increasing flexion.

[1]  K. Lewit,et al.  [MEASUREMENTS OF FLEXION AND EXTENSION IN THE JOINTS OF THE HEAD]. , 1963, Fortschritte auf dem Gebiete der Rontgenstrahlen und der Nuklearmedizin.

[2]  B L Braun,et al.  Quantitative assessment of head and shoulder posture. , 1989, Archives of physical medicine and rehabilitation.

[3]  Shrawan Kumar,et al.  Effect of body posture on isometric torque-producing capability of the back , 1991 .

[4]  J. Fielding.  Cineroentgenography of the normal cervical spine. , 1957, The Journal of bone and joint surgery. American volume.

[5]  B. Bigland-ritchie,et al.  Changes in muscle contractile properties and neural control during human muscular fatigue , 1984, Muscle & nerve.

[6]  K Schüldt,et al.  On neck muscle activity and load reduction in sitting postures. An electromyographic and biomechanical study with applications in ergonomics and rehabilitation. , 1988, Scandinavian journal of rehabilitation medicine. Supplement.

[7]  K Schüldt,et al.  Maximum neck extension strength and relative neck muscular load in different cervical spine positions. , 1989, Clinical biomechanics.

[8]  Manohar M. Panjabi,et al.  Clinical Biomechanics of the Spine , 1978 .

[9]  M M Panjabi,et al.  Cervical spine motion in the sagittal plane: kinematic and geometric parameters. , 1982, Journal of Biomechanics.

[10]  H. van Mameren,et al.  Cervical Spine Motion in the Sagittal Plane II: Position of Segmental Averaged Instantaneous Centers of Rotation -A Cineradiographic Study , 1992, Spine.

[11]  J S Petrofsky,et al.  Neck muscle loading and fatigue: systematic variation of headgear weight and center-of-gravity. , 1983, Aviation, space, and environmental medicine.

[12]  J Perry,et al.  EMG-force relationships in skeletal muscle. , 1981, Critical reviews in biomedical engineering.

[13]  K. Lewit,et al.  [Contribution to flexion of the cervical spine]. , 1962, Fortschritte auf dem Gebiete der Rontgenstrahlen und der Nuklearmedizin.

[14]  B M Bowman,et al.  Prediction of head/neck dynamic response of selected military subjects to -Gx acceleration. , 1978, Aviation, space, and environmental medicine.

[15]  G. Németh,et al.  Load moments and myoelectric activity when the cervical spine is held in full flexion and extension. , 1986, Ergonomics.

[16]  A. Schultz,et al.  Analysis and measurement of neck loads , 1988, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[17]  E D Ross,et al.  Speed of movement, gravity, and the neural coordination of muscular actions. , 1983, Electromyography and clinical neurophysiology.