Studies in the Osteopathic
Basic Principles: Volume
Louisa Burns, M.S., D.O., D.Sc.O.
THE EXPERIMENTAL DEMONSTRATION OF THE OSTEOPATHIC CENTERS:
Cardiac Viscero-Somatic Reflexes.
centers for the heart were determined in much the same manner as were the
electrodes were placed first upon the different parts of the parietal pericardium.
This stimulation was followed by contractions of the muscles near the fourth
thoracic spine. The areas of the third and fifth nerves were also
affected in some animals, but the muscles innervated from the fourth thoracic
nerve were always affected, as were also the intercostals of the same area.
The intercostals of the third and fifth nerves were more frequently affected
than were the spinal muscles of the same area.
stimulation of the visceral pericardium gave the same reactions as did
also the stimulation of the heart muscle. The direct stimulation
of the heart muscle, however, initiated one reaction which was not found
in connection with the stimulation of the pericardium. This was the
contraction of the cervical muscles. The trapezius was almost invariably
affected, and the scaleni very often. Other cervical muscles were
reflexly contracted in reply to stimulation of the heart muscle in varying
degrees in different animals. No difference in the position of the
muscular contraction could be determined in relation with the stimulation
of the different valves. Indeed, it was very difficult to secure
any reactions in answer to the stimulation of the valves or of the endocardium,
unless the strength of the current was so greatly increased as to affect
the heart muscle also. The sensory nerves of the heart are evidently
distributed to the cardiac musculature more freely than to the endocardium.
Cardiac Somato-Visceral Reflexes.
stimulation of the tissues near the fourth thoracic spine initiated changes
in the heart beat which are of two kinds. In some individuals the
strength of the beat is increased, in others the rate, while in yet others
both rate and force are increased. Whether this difference is due
to some imperceptible difference in the manner of giving the stimulation,
or whether it is due to some physiological difference in the metabolism
of the neuron systems concerned, or whether it is due to structural peculiarities
or to some other factor, we do not know. This is one of the points
which awaits further investigation. The facts are as stated.
of the tissues near the fourth thoracic spine of an animal whose thorax
has been opened under anesthesia affects the pulmonary blood vessels rather
than the heart. The heart is quickened if it is affected at all.
Without anesthesia or mutilation, the heart is always quickened, and usually
the beat seems somewhat less forceful to the touch.
Direct Stimulation of the Sympathetic.
stimulation of the sympathetic ganglia in the upper thoracic region caused
great increase in the rate of the heart beat. Direct stimulation
of the vagus above the superior cervical ganglion decreased the pulse rate.
Stimulating manipulations of the vagus, in the absence of anesthesia or
mutilation, lessened the rate if the stimulation were given high in the
neck, but increased the rate if the stimulation were given just above the
clavicle,--or rather, in animals, the place were the clavicle would be
if there were one. The reason for this seeming anomaly is that the
sympathetic fibers which reach the heart are carried with the vagus from
their exit from the superior, middle or inferior cervical ganglia.
The accelerators are more immediately effectual, hence the stimulation
of the nerve trunk at a point where it carries both kinds of fibers causes
the accelerator effect to be most evident.
of the vagus below the heart, as, for example, just above the diaphragm,
initiates inhibitor influences to the heart. These are reflex, and
are of the same nature as those impulses of gastric origin which interfere
with the heartís action under certain abnormal conditions. Stimulation
of the vagus nerve in the neck is rather an easy matter; its inhibition
is rendered rather difficult by the presence of the pulsating carotid artery.
Pressure upon the nerve increases the effect of the pulsations of the artery
upon it, and the effect of this is the stimulation of the vagus, rather
than its inhibition.
most satisfactory experiments upon the action of the heart centers were
performed upon persons.
Experiments Upon Human Subjects.
of the tissues near the fourth thoracic spine caused an increase of as
much as fifteen beats per minute in the pulse rate. In those persons
in whom the rate was greatly increased, the force of each beat was somewhat
lessened. The utmost efforts at stimulation were unable to increase
the pulse rate at all in some individuals.
all, when efficient stimulation was given, the blood pressure was raised.
This reaction was no doubt partly due to the simultaneous reflex stimulation
of the pulmonary vaso-motors, and in part to the cardiac effects.
The rise of blood pressure thus produced may amount to twenty millimeters
of mercury in some individuals. In others, the effects are much less
pronounced. Efficient stimulation always produces some change, however
in a normal person.
effect of this stimulation upon the sphygmogram is usually very pronounced.
In persons whose muscles are very heavy, and who have been of robust health
for a long time, it requires a considerable amount of strength to effect
the deeper muscles in sufficient degree to effect a perceptible change
in the sphygmogram.
sphygmogram, normal, resting pulse. Rate, 71. Blood pressure,
125 m.m. of mercury.
Lower sphygmogram, after two minutes of the ďartificial lesionĒ the fourth
thoracic spine. Rate 82. Blood pressure, 112 m.m. of mercury.
Upper sphygmogram, normal, resting pulse. Rate, 72. Blood pressure,
119 m.m. of mercury.
Lower sphygmogram, after two minutes of the ďartificial lesionĒ at the
fourth thoracic vertebra. Rate 63. Blood pressure, 113 m.m.
Stimulation of Heart Center.
is usually easy to secure rather striking variations in the sphygmograms
in reply to the stimulation of the heart center by somato-sensory impulses.
These experiments were performed in the following manner:
The subject was permitted to rest until the pulse displayed no further
The normal, resting sphygmogram was then taken upon about half the strip.
The clockwork was then stopped while the stimulating movements were given
to the tissues near the fourth thoracic spine for two to four minutes.
The sphygmograph was then started, and the character of the pulse tracing
noted. If no change was perceptible, the stimulation was repeated.
The second attempt was always successful, if the stimulation was properly
given. The sphygmogram showed increased rate, or force, or both.
If the rate were greatly increased, the force of each wave was sometimes
less than before the stimulation was given. If the force was greatly
increased, the rate sometimes remained nearly or quite unchanged.
It has never occurred that the rate was decreased unless there were some
abnormality present. Under normal conditions, the efficiency of the
heartís beat is always increased by this stimulation.
Inhibition of Heart Center.
artificial lesion in the neighborhood of the fourth thoracic spine lessens
the efficiency of the heart beat. This is due either to decreased
rate, or decreased force, or both, at first, but after a few minutes persistent
inhibition, or the maintenance of the lesion for a few minutes, the beat
becomes quick and weak in all cases.
sphygmograms taken after prolonged treatment of this kind show the decreased
power of the up stroke; it is not so high as before, and its slant is greater.
systemic arterial pressure is decreased at the same time. This decrease
in blood pressure is no doubt partly due to the dilatation of the pulmonary
vessels, but in part it depends upon the lessened efficiency of the heartís
some of the subjects of these experiments, the inter-scapular muscles were
contracted in an abnormal manner, and the manipulations were painful.
Any manipulations which were given secured the relaxation of the stiffened
muscles and a temporary return to the normal condition of the pulse.
The effect was usually only temporary, except in a few cases in which the
muscles had been stiffened by some temporary condition. In these
cases, the manipulations afforded the temporary relief which was all that
the conditions required.
pressure upon the sensory nerves which is maintained by muscles which are
kept contracted is exactly the same in kind as the pressure which is exerted
by the fingers in the experiments in inhibition. The effects are
the same, except that the contracted muscles persist in their pressure
for days and nights, until the neurons concerned are exhausted. The
relief of the abnormal contractions, however secured, stops the abnormal
sensory impulses and permits the normal relations to be effectual as soon
as the neurons are able to regain their normal metabolic conditions.
effects of abnormal conditions effecting the vagus are very irregular.
The experimental pressure upon the trunk of the vagus in the animal produces
at first a slowing of the heart. This is followed by a period of
irregular rhythm, and this is maintained as long as the pressure is continued.
The irregularity of the rhythm noted in these cases is probably due to
the complexity of the factors which regulate the heartís action.
appears from these experiments that the action of the heart may be affected
by somato-sensory impulses from the area of distribution of the fourth
thoracic nerves, and that those movements are most effectual which affect
the relations of the joint surfaces.
conditions affecting the somato-sensory impulses carried over the third,
fourth and fifth thoracic nerves may exert a direct influence upon the
condition which affects the sensory fibers of the vagus may affect the
action of the heart.
No aid in
the diagnosis of valvular lesions is to be expected from the existence or non-existence
of reflex muscular contractions in the inter-scapular region.