The Abdominal and Pelvic Brain
Byron Robinson, M. D.



The sympathetic nerve which rules visceral rhythm never sleeps. Visceral rhythm (peristalsis) and life are beyond the control of the will.

A Precedent is the terror of second rate men." - Dr. Joseph Parker.

    The physiology of the abdominal and pelvic brain with automatic visceral ganglia comprehends the real physiology of the sympathetic, as the chief portion of the former is included or counted in the latter.  It may be asked, "What is understood by the physiology of the sympathetic nerve?" We understand by the physiology of any organ the use it yields to the economy, or the purpose it subserves to the animal.  It may be stated in the beginning that it is difficult to definitely and exactly define the physiology of the sympathetic nerves, as they are often largely mingled with those of the cerebrospinal system.  The cerebrospinal and sympathetic systems of nerves have a certain initial dependence on each other, like the individuals of well ordered society.  Yet certain limited liberties are assumed by both systems.  The Federal government presides as a central power over the various states, but the latter assume many independent liberties of action.  The states act and execute independently of the central government.  So it is in the human body, an exquisitely perfect product of millions of ages; the sympathetic nerve, though dependent for much of its power on the cerebrospinal axis, has in its influence over circulation and the abdominal viscera a certain independence of function.
    The sympathetic is not merely an agent of the brain and cord.  It generates action itself.  It is, in general, a nerve center characterized by the power to receive sensation and send out motion., It has all the elements of any nervous system, viz.: a ganglion cell, a conducting cord, and a periphery.  It is not attempted here to argue that either the cerebrospinal axis or the sympathetic nerve is absolutely independent of the other.  The fact is that each nerve system has its own special duties.  Both systems must be associated in order to carry on life's functions and purposes.  It may be said that man and woman are independent of each other; but their association is required for the perfection of reproduction.  In another place I have arranged quite a number of propositions to show that the sympathetic nerve enjoys a large degree of independence.  In the discussion of its physiology certain topics must be discussed, in order to better comprehend the limits and factors of the field.

    1.  The abdominal pelvic brain, i. e., reorganizing centers.
    2.  A very important factor will be the vaso-motor nerves (i. e., vaso-constrictors and vaso-dilators).
    3.  The automatic visceral ganglia.
    4.  Glandular secretions (bile, urine, gastrointestinal juices, milk, ova and semen).
    5.  Temperature.
    6.  Trophic nerves.
    7.  Pigmentation.
    8.  Reflex fibers.
    9.  Sleep.

    The above nine divisions mark out a field for consideration.  It may be broadly stated that all healthy movements initiated and sustained by the sympathetic nerves are involuntary movements.
The vaso-motor nerves.  They are divided into vaso-constrictors and vaso-dilators, and to Claude Bernard belongs the credit of first conclusively showing (in 1851) that they exerted an influence over the caliber of the vessels.  Authors agree, in general, that here are vaso-motor centers located in the spinal cord which control the caliber of vessels.  Some place the vaso-motor centers in the vascular columns of Clark.  Still another set of authors of great respectability claim that vaso-motor centers are located along the peripheral nerve branches.  Doubtless there are in the walls of vessels nerve cells which are in connection with the vaso-motor nerves.  These vascular ganglia, or nerve cells send fibers to the muscularis of the vessel, dilating or contracting it according to the nature of the despatched stimulus.
    It is not yet definitely settled whether the vaso-motor nerves are constrictors or dilators, or whether there are distinct constrictors and dilators.  Some assert that there is a constrictor nerve only and that dilation of the vessel is paresis of the constrictor.  Later authority seems to point to a vaso-dilator and vaso-constrictor, and the fact that there are vaso-motor centers located on the vessel or adjacent to it.  It is evident to observers and clinicians that local variation of circulation occurs in the genital or digestive tracts from reflex irritation.  By slight irritation one can produce a white line (vaso-constriction) and by more severe irritation one can produce a red line (vaso-dilation).  Cold first constricts the vessels, but it is rapidly followed by vaso-dilation, a redness.  Now, this local variation of circulation occurs doubtless with more distinctness in the visceral organs which are so highly supplied with vaso-motor nerves, and so closely situated to the gigantic vaso-motor center, the abdominal brain.  The significance of vasoconstricting nerves becomes very evident when it is recognized that they are so powerful that they can drive or squeeze all the blood out of a part.
    In death from peritonitis the vaso-constrictors drive first all the blood out of the skin or periphery.  The blood is forced into the large arteries and veins by the effect of the vaso-constrictors on the peripheral and smaller vessels.  The vaso-dilators may be so effectively exercised that the blood escapes through the wall of the blood-vessels as in hemorrhagic peritonitis.
    The vaso-motor nerves are of the sympathetic and exercise control over the caliber of vessels.  The controlling of the lumen of vessels constitutes a vast field of physiology, in the domain of the sympathetic.  It constitutes vascular tone.  Section of the sympathetic dilates the vessels beyond the normal.  One of the chief offices of the sympathetic nerve is to preserve tone of vessels.  The nerves that insure tone in vessels issue from the sympathetic.  They are always active and never in repose, - a characteristic of the sympathetic nerve.  They pass to the muscular coat of the vessels and act as their permanent guardian, in preserving permanent vascular tone.  Variation in this tone constitutes incipient disease.  Doubtless the vascular tone is the result of a reflex matter, and the factor in the reflection is the blood-wave, i. e., the trauma or irritation of the blood-wave on the endothelial membrane of the vessel induces the vaso-constrictors to act permanently in preserving vascular tone.  Congestion is only the abolition of vascular tone.  Goltz's percussion experiment demonstrates the reflex nature  of the action of vaso-motor nerves, as by tapping on the exposed viscera he could produce dilatation of their vessels.  Hence in this case the centers for  reflex action must lie in the walls of the vessels themselves.
    For a reflex act in the vaso-motor field, there must exist several factors, as (a) muscular walls or contractile tissue; (b) centripetal fibers; (c) a center of reflection; (d) centrifugal fibers.
    All these factors exist on and adjacent to vessels.
    For the reflex centers of vaso-motor movements we may look to the cardiac ganglia, the abdominal brain or, especially, to the ganglia around the vessels or in their walls.  Finally, we may claim that the vaso-motor nerves control the caliber of vessels, that they belong to the sympathetic and that those of the abdominal viscera are chiefly under the control of the gigantic vaso-motor center - the abdominal brain.
    First, we must consider the abdominal brain, the semilunar ganglia or solar plexus, in the physiology of the sympathetic.  This large ganglion receives sensation and sends out motion.  It is situated at the root of the great visceral artery i. e., at the foot of the celiac axis.  It lies behind the stomach and entwines itself about the aorta and root of the celiac axis and superior mesenteric artery.  In short, it is located at the roots of the celiac, renal and superior mesenteric arteries.  It supplies all the abdominal viscera.  It is a gigantic vaso-motor center for the viscera, as is shown by its location at the roots of the celiac, renal and superior mesenteric arteries - the great abdominal visceral blood way.  It is connected with almost every organ in the body, with a supremacy over visceral circulation, with a control over visceral secretion and nutrition, with a reflex influence over the heart that often leads to fainting and may even lead to fatality.  It rules visceral rhythm.  No wonder that we may consider the abdominal brain the center of life itself, as the cranial brain is the center of mental and Psychical forces!
    The abdominal brain, or solar plexus, is composed of the aggregation of coalescence of a large number of ganglia.  On the two sides of the abdominal brain are situated the semilunar ganglia - compact masses of nerve cells, nerve cords and connective tissue.  During many dissections I have noted that the right semilunar ganglion is the smaller, doubtless because it lies behind the inferior vena cava, and hence has suffered from pressure atrophy.  Each of the semilunar ganglia receives the great splanchnic nerve of the corresponding side.  The other splanchnics may enter it, but it is more to enter the abdominal brain.  It may be here stated that although the semilunar ganglia are located on the sides, they are practically so intimately associated with the solar plexus that we insist in combining all the names into one, viz.: that of Abdominal Brain.
    All plexuses or strands of nerves are secondary.  The significance of the abdominal brain in the visceral physiology, i. e., in life, may be compared to that of the sun over the planets.  The influence of the sun rules the planets, though they are influenced by other suns and planets (e. g., the cerebrospinal).  The abdominal brain has ganglion cells (brain centers), nerve strands (nerve conductors) and a peripheral nerve apparatus, just as the cranial brain possesses a central, conducting and peripheral apparatus.  The abdominal brain can live without the cranial (shown by living fetuses with no trace of cerebrospinal axis), while the cranial brain and the cord cannot live without the abdominal brain.
    The great sympathetic ganglia, of which the abdominal brain is the ruling potentate, is the center of life itself.  So long as the forces of life, assimilation, circulation, respiration and secretion proceed undisturbed, as in health, the abdominal brain remains a silent, steady, but ceaseless worker; but being unbalanced by peripheral or central irritation, it quickly manifests or resents the insult.  From the abdominal brain large plexuses with numerous nerve strands pass to every abdominal viscus, connecting the viscera into a delicately balanced, nicely ordered, exquisitely, arranged apparatus for the object of maintaining life.  The nerve plexuses or strands are arranged along the highways of nourishment - blood and lymph vessels, and vary in size according to the importance of the viscus supplied.
    Laignel and Lasvastine, in their experiments upon dogs, have found that ablation of the solar plexus is a serious operation; though traumatism of the plexus even may cause death.  They have called the solar syndrome of paralysis the sum of symptoms produced by ablation of the plexus; it may be superacute, acute, subacute, or chronic.  The first form they have found to be present in peritonitis, clinically, the second in lead colic; the others in mucomembranous colitis.  Certain affections, therefore, may be attributed solely to disturbance of the solar plexus, and not to general systemic derangement.