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3.1.2.1. Regional body surface motion in 
very 
The process of breathing is remarkably 
complex and our understanding of it is 
incomplete even at the qualitative level. 
Interest in the study of respiratory 
motion stems from the insight this gives 
into the function of the respiratory 
muscles; the only skeletal muscles in the 
body essential to life. 
Since respiratory muscle weakness is an 
important factor in the genesis of acute 
respiratory failure, it has become 
important to gain a better understanding 
of their function. 
A near real-time biostereometric method 
using stereometric CCD cameras is 
presently in use at the Department of 
Paediatrics and Child Health for clinical 
research studies at the Red Cross War 
Memorial Children's Hospital in Cape 
Town. The system allows for the precise 
Spatial determination of targetted points 
on the chest at any given time (Adams et 
al, 1990). 
A part pictorial demonstration of a 
"funnel" chest is shown here: 
Plots of Epoch Difference 
Breath-in minus Breath-out 
  
  
  
  
DISPLACEMENT VELTORS DISPLACEMENT VECTORS 
4 
INSPIRRTORY TORSO MOTION INSPIRRTORY TORSO MOTION 
  
  
  
  
  
  
  
X Y Displacement Z Displacement 
Vectors Vectors 
  
  
  
  
Contour plot 
  
3.1.2.2. Human head movements. 
Using a pair of synchronised CCD cameras 
in stereometric mode, the movement, in 
three dimensions, of a reference point 
attached to the face of a number of 
normal subjects, were determined stereo- 
photogrammetrically as the subjects moved 
their heads in flexion, extension, 
laterally and right and left axial 
rotation. From these measurements , the 
surfaces, described by the reference 
point in the various movements, could be 
mathematically ascertained. In the event, 
the surface described proved to be a very 
close approximation to an elliptical 
paraboloid with a tendency towards a 
sphere. An interesting result since this 
would imply that there is a single point 
of rotation; the centre of the "sphere" 
  
A normal Subject being recorded during 
axial rotation. Note:The targetted harness 
allows for shoulder movements to be 
mathematically isolated from head 
movements. 
Interpretation of this unexpected finding 
is not straightforward since cervical 
movements result from 23 individual 
synovial joints in the neck which, 
together, permit different planar 
movements, rotations and shear motion. 
Panjabi et al (1988) showed that the 
greatest intervertebral motion in the 
cervical spine was axial rotation, at the 
C1-C2 joint, and flexion/extension at the 
occiput-C1 joint.Having established 
stereophoto-grammetrically that the 
combined motion of a point on the face 
described the surface of an elliptical 
paraboloid, with a tendency towards a 
sphere, it was considered interesting to 
attempt to explain the findings by 
studying the geometry of the surfaces of 
the articulating facets of the occiput-C1 
and C1-C2 joints, since the greatest 
movements took place at these 
junctions.Six macerated, human adult, 
whole cervical spine specimens (base of 
skull to C7) were obtained. Using the 
reflex microscope, measurements were 
concentrated on the articulating bony 
joints of the skull with C1 superior and 
Cl inferior with C2 superior. In the 
event, it has been established that the 
bony surfaces of the occiputal condyles, 
C1 superior and C2 superior pairs of 
articulating facets all form part of the 
surface of individually common elliptic