Studies in the Osteopathic
Basic Principles: Volume
Louisa Burns, M.S., D.O., D.Sc.O.
THE EXPERIMENTAL DEMONSTRATION OF THE OSTEOPATHIC CENTERS:
series of experiments described in this chapter some of the work of Dr.
Pearl A. Bliss in her demonstration of the vaso-motor nerves of the lungs
will be used.
Pulmonary Viscero-Somatic Reflexes.
thorax was opened under ether narcosis. A. Du Bois-Raymond coil was
used for the electrical stimulation. The current was not measured
but was barely perceptible to the touch of the wet finger. The electrodes
were first applied to the visceral pleura of the upper lobe of the left
lung. The first intercostals of the left side were strongly contracted.
The muscles near the second thoracic spine were also contracted on both
sides. After the stimulation had been maintained for several minutes,
the intercostals of the right side, the muscles of the neck, especially
the scaleni and the sterno-cleido-mastoid, and nearly all of the inter-scapular
muscles became somewhat contracted.
electrodes were then placed upon different areas of the visceral pleura.
The intercostals normally covering the area stimulated were first contracted.
Stronger stimulation initiated the contraction of the corresponding intercostals
on the opposite side also.
lobes of the lung were then displaced, but not cut. The stimulation
of the visceral pleura of any part of the lung was followed by the contraction
of the intercostal muscles normally covering that part, and by the contraction
of the spinal muscles of the same and adjoining segments. This proved
that the reactions observed were not due to any local effect of the electrical
current, but were true reflexes, initiated by the electrical stimulation
of the sensory nerves of the pleura.
of the diaphragm, the quadratus lumborum, and occasionally the abdominal
muscles followed the stimulation of the lower lobes of the lungs.
In the dog, the inferior lobe on the right side lies next to the diaphragm
but does not touch the thoracic wall. The stimulation of this lobe
initiated the reflex contraction of the diaphragm but not of the intercostals
unless the stimulation was maintained for some time. The division
of the phrenic prevented this last reaction.
removal of the visceral pleura in the areas stimulated rendered the reactions
much more diffuse,--that is, the reflex muscular contractions were not
so strong, and involved a much larger area. They were otherwise unchanged.
The phenomenon probably indicates that the innervation of the pleura is
more nearly exactly segmental than is the innervation of the pulmonary
epithelium. This accords with circumstances of the development of
these tissues. The pulmonary epithelium arises as an out growth from
the pharyngeal epitheliuim, and as it grows downward it carries with it
its original nerves, the vagi, and later receives its vaso-motors with
its blood vessels. The pleura, on the other hand, is developed in
place from the mesoblast of that region, and retains both its position
and its innervation throughout life.
Section of the Vagus.
section of one or both vagi above the superior cervical ganglion did not
perceptibly affect the results. Section of both vagi below the superior
cervical ganglia lessened the reactions in a very variable manner in different
animals. After section of both vagi below the stellate ganglia, or
after the extirpation of the stellate ganglia without injury to the vagi,
or after the destruction of the upper part of the spinal cord, no contraction
of striated muscles could be discerned upon the administration of such
stimulation as we were employing.
spinal muscles were variously contracted during the application of the
stimulation to the lungs. The most marked contractions were noted
in the area of distribution of the second, third, fourth, and fifth spinal
nerves. There is a slight appearance of segmentation in the areas
of these reflex contractions. Hence, the location of the reflex muscular
contractions affords some information concerning the location of areas
of irritation in the lungs and pleura, especially in the early stages of
disease, before the reflexes have become spread into the neighboring segments.
place of these reflexes in pathology may be referred to briefly in this
connection. The irritation of the pleura by any of the causes of
its disease initiates the contraction of the intercostals covering the
affected area, and rest is thereby secured for the injured tissues.
If the irritation is very severe, the whole thorax becomes practically
immovable. Conversely, the contraction of these spinal muscles exerts
an influence upon the circulation and nutrition of the injured lung which
is at first curative, but becomes decidedly detrimental to recovery if
the irritation be long continued.
Pulmonary Somato-Visceral Reflexes.
relations determined by these experiments were held indicative of certain
possibilities in testing the nature of the somato-visceral reflexes.
In the first experiments the electrodes were placed upon the skin in the
area of distribution of the chosen nerve. The visceral effects thus
secured were inconspicuous and inconstant. The fact that any visceral
effects were secured, even though they were neither constant nor pronounced,
shows that the skin may, in occasional cases, be a source of visceral malfunction
through the reflex effects upon the visceral nerves. Since the skin
and other superficial tissues are normally subjected to great variations
in stimulation, the changes needful to produce any considerable visceral
effect must be very great or else very unusual in their quality.
The visceral effects following the injury of extensive skin areas are probably
produced in this way.
stimulation of the sensory nerves in the deeper muscles, articular surfaces,
and adjacent tissues initiated decided visceral effects. Those movements
which affected the joint surfaces most urgently were most effectual in
producing vascular changes.
thorax remaining intact, and the abdomen being opened, the color of the
lungs was noted through the central tendon of the diaphragm. In dogs,
this tendon is usually very large and thin, and the changes in the color
of the lungs can be seen quite easily in a good light. In cats, the
central tendon is smaller and thicker. Hence the cat is not a proper
subject for this experiment. In dogs, mechanical stimulation of the
deeper tissues near the fourth and fifth thoracic spines was followed,
after a latent period of from one to three minutes, by a lightening in
the color of the lungs. After a few minutes rest they began to redden
again, becoming somewhat deeper in color than they were before the stimulation.
The stimulation was again given in the same area, when the lungs again
became lighter, only to redden again under rest. There seemed to
be no limit to the number of times the reaction could be repeated, provided
the anesthesia were not too profound, and provided sufficient time were
given for the return to the normal condition between the periods of stimulation.
It is evident that the changes observed were due to changes in the caliber
of the pulmonary blood vessels.
performed in the same manner, except that the stimulation was applied to
other spinal areas, or to the trunk of the vagus, were not successful.
No stimulation of the vagus seemed to exercise any effect upon the circulation
through the lungs except those evidently attributable to cardiac effects.
Certain effects were produced upon the bronchial musculature by stimulation
of the vagus which required further investigation.
with the thorax intact and the abdomen opened, the fourth and fifth thoracic
spines were held firmly in such a manner as to force them slightly out
of their normal alignment, without actually dislocating the vertebrae.
Thus the “artificial lesion” was produced. After a latent period
somewhat longer than before, the lungs became redder than normal.
appearance persisted as long as the lesion was maintained. If the
lesion were removed quickly, the normal color slowly returned. The
longer the lesion was maintained, the longer the time required for recovery.
Recovery from the second experiment upon the same animal was very slow,
and the animal often died before recovery from the third experiment, even
though the lesion had been maintained each time only long enough for the
effects to become manifest.
the next series the thorax was opened. The same effects followed
the same manipulations. Stimulation of the tissues near the second
and third thoracic spines seemed to produce greater effects upon the circulation
in the upper lobes of the lungs than did the stimulation of the tissues
near the fourth and fifth spines. No actual measurements were possible
under the conditions of our experiments, but differences in the color changes
seem to warrant the statement just made. It is apparent that the
somato-visceral reflexes are much more diffused and irregular than the
corresponding viscero-somatic reflexes.
of the tissues near the second and third thoracic spines affected many
other tissues also, and for this reason it seems probable that the centers
most effective for modifying the circulation through the lungs are found
near the origin of the fourth and fifth thoracic nerves.
order to eliminate cardiac effects, the cardiac nerves were all divided
The reactions described above did not vary after the section, except that
the animal did not live so well under anesthesia, and the experiments could
not be so often repeated.
Experiments Upon Human Subjects.
following experiments upon human beings can be repeated quite easily.
The subject was permitted to rest quietly until the blood pressure remained
constant. The blood pressure was then estimated by means of the sphygmomanometer.
Stimulation of the tissues near the origin of the fourth and fifth thoracic
nerves was followed by a rise in blood pressure, such as would be caused
by the contraction of the blood vessels in any marked area of the circulatory
system. In the light of the experiments upon animals just described,
it appears that this increase in blood pressure is due to the decrease
in the size of the pulmonary vessels.
steady pressure at the sides of the spines, or the maintenance of an artificial
lesion in the same area, is followed by a decrease of blood pressure, such
as would follow a dilatation of the vessels in any large area of the vascular
system. This effect is, for the same reasons, held to be due to the
lessened action of the pulmonary vaso-constrictors.
4 and figure 5 show the effects of these manipulations upon the respiratory
curves. The subjects were permitted to remain quiet upon a treating
table until no further change in pulse or respiration could be detected.
The normal curve was then taken, then the manipulations administered, then
a second tracing was taken, with the same apparatus similarly placed.
These curves were taken many times with many different persons as subjects,
and the results were always alike, in the main, though they differed considerably
in detail. In many instances, the curves varied in answer to the
manipulations very much more than do those which were used in the cuts.
These were chosen as representative of the average changes produced by
the manipulations described.
respiratory curves were taken with Marey’s tambour. This consists
of two pans connected by rubber tubes. Both pans were covered with
thin sheet rubber. One pan was bound over the apex beat of the heart,
the other supported a needle which played upon a smoked paper around the
revolving drum of a kymograph. The pressure of the respiratory
movements and of the heart beat was transmitted through the fluid in the
first pan, then through the tube to the second pan, where the needle was
affected, and the needle wrote the record upon the smoked paper.
The paper was then varnished and the records preserved. The large
waves are those produced by the respiratory movements, and the smaller
waves superimposed upon the respiratory curves are made by the heart beat.
tracing, normal, resting, respiratory curve. Blood pressure, 110
m.m. of mercury. The smaller waves were made by the heart’s beat.
tracing, respiratory curve after the maintenance of an artificial lesion
of the fourth thoracic vertebra for three minutes. Blood pressure,
99 m.m. of mercury.
lesion causes slight dilatation of the pulmonary vessels, increased oxygenation
of the blood, and decreased activity of the respiratory center. The
decreased blood pressure is due to the dilatation of the pulmonary vessels.
tracing, resting, normal respiratory curve. Blood pressure, 116 m.m.
of mercury The smaller waves were made by the heart’s beat.
tracing, respiratory curve after stimulation of the tissues near the fourth
thoracic spine. Blood pressure, 121 m.m. of mercury.
stimulation caused constriction of the pulmonary vessels, decreased oxygenation
of the blood, and increased activity of the respiratory center.
was noted in the observations upon anesthetized animals that the reflex
effects upon the heart disappeared much more quickly under the anesthesia
than did the vaso-motor reflexes That is, under anesthesia the cardiac
nerve centers first lose their power of replying to sensory impulses, while
the irritability of the vaso-contrictor centers persists under more pronounced
anesthesia. This is true also of the same nerve centers during the
process of dying under certain other poisons.
experiments upon human beings were, of course, carried on without anesthesia.
The cardiac centers were therefore, normally active. When the human
subject slept, however, the cardiac reflexes were less conspicuous than
the vaso-motor reflexes, just as in the case of the anesthetized animals.
It seems that sleep and anesthesia alike differ from the waking condition
in this particular case, as well as in others which are more familiar.
these experiments upon human beings, the effects described in this chapter
were constant only as described if the subject were in fairly normal condition.
If the inter-scapular muscles were contracted or if the manipulation was
painful the effects varied in some instances. Any manipulation, whether
stimulating movements or steady pressure, seemed to effect the relaxation
of the muscles, and a return to the normal condition.
effects are explained as follows:
the period of the abnormal contraction of the inter-scapular muscles, however
produced, the reflex effect upon the pulmonary vessels was such as was
produced by the steady pressure of the experimenting fingers. The
vessels were dilated in the same manner as was seen in the vessels of the
animals subjected to the same experiment. Any manipulation of these
muscles resulted in their relaxation, and in the return of the whole circle
of sensory, vaso-motor and associated neurons and the vascular musculature
to the normal condition. It seems that contracted muscles or bony
lesions in the area of the lung center or its immediate neighborhood exert
an inhibiting influence upon the vaso-motors of the lungs, leading to their
dilatation, and to low systemic arterial pressure. The relaxation
of these muscles or the removal of the lesions, however secured, removes
the source of the abnormal sensory impulses. Then the circulation
becomes normal as soon as the vascular walls and the neurons affecting
them recover from the effects of the abnormal influences.
Vaso-Motors, Dr. Pearl A. Bliss, A. O. A. Journal, August, 1907.