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



The rectum is guarded by two sphincters, viz., a larger proximal one supplied by the sympathetic, and a smaller distal one supplied by the cerebrospinal nerves.

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    In experiments on various animals and by clinical observation on man we may note various kinds of bowel movements.  For the purpose of making the subject more intelligible we may note that the bowel wall is composed of an outer longitudinal muscular layer and of an inner circular muscular layer.  The bowel is lined by a mucous membrane and covered by a serous or peritoneal membrane.  The arterial supply is carried from the celiac axis to supply the stomach (gastric artery); from the superior mesenteric artery to supply the small intestines, the ascending colon and transverse colon; from the inferior mesenteric to supply the descending colon, sigmoid and rectum - in all, three segments supplied by three arteries.  The nerve supply to the intestines is from three sources:.
    1.  The cranial nerve (the pneumogastric).
    2.  The spinal nerves, especially those entering at the distal and proximal bowel segment.
    3.  The sympathetic system.
    The nerve supply of the bowel is a mixed supply of cerebrospinal and sympathetic.  In the sympathetic nerve supply of the bowel we must name some four sources, viz.:
    (a)  The Auerbach plexus (myentericus externus), situated between the circular and longitudinal muscular layers of the bowel wall.  It is a nerve plexus supplying muscles.
    (b) The Billroth-Meissner plexus (myentericus internus), situated under the mucosa.  It is a nerve plexus supplying glandular structure and has to do with secretion.
    (c)  The abdominal brain (the solar plexus), situated around the origin of the celiac axis, the superior mesenteric and renal artery.
    (d) The lateral chain of sympathetic ganglia, located along each side of the vertebral column.  From this chain of ganglia arise the great splanchnic nerves (three or four).  With a mixed nerve supply we must designate the character of the movement by the nerve which preponderates.  The characteristic movements of the bowel are those of a rhythm, rising slowly to a maximum (spasm) and sinking slowly to a minimum (rest).
    The rhythmic, periodic movement belongs to the sympathetic nerve.  So that wherever the initiation or inhibition of motion may reside for the bowel wall, it is dominated by the sympathetic nerve, like all other abdominal viscera With this mixed nerve supply variously localized we may turn to the physiologic movements of the intestinal tract:
    1.  The peculiar peristaltic movements, which consist of a contraction and dilatation of the bowel lumen. - The motion is towards the anus and the contents move in the same direction.  The most typical animal which I have examined to study the bowel peristalsis is the rabbit.  In the rabbit the contraction and dilatation of the bowel wall is very rapid, traveling a foot in a few seconds.  Of course this rapid traveling cannot force the feces with it.  The analward wave is transmitted from one segment of the bowel to the other, in rapid succession.  But with the abdomen open and the bowel struck or pinched or irritated, we must think of every successive physiologic action. The peristalsis borders on pathologic conditions.  In fact, one can really see that the bowels move in a wild, irregular confusion.  By pinching the bowel wall with the finger and thumb or forceps a circular constriction will arise which resembles a pale, white ring. almost closing the bowel lumen, and persisting awhile.  This analward alternate contraction and dilatation of the bowel wall is a physiologic process of the bowel, and doubtless is not accompanied by pain unless there be a diseased segment, when pain may arise.  The peristalsis of the bowel is perhaps limited to a bowel with contents, i. e., its contents, or, in other words, mechanical irritation that produces physiologic peristalsis.  In laparotomy if one will observe, the empty bowel is nearly always still unless irritated by manipulation.  If one will watch the bowel waves of peristalsis it will be apparent that the peristaltic waves are limited from three to twenty-four inches.  A peristaltic wave will start and stop within a localized space.  In the dog the peristaltic wave is neither so rapid in its travel nor does it seem to travel over such a long distance.  The intensity of peristaltic waves is most marked toward the proximal end of the jejunum where the muscular fibers, blood and nerve supply are large.  The bile and pancreatic duct pour their contents into the proximal end of the bowel, and thus impel the peristaltic waves to force the contents distalward.  For secretion or the presence of any bowel contents is what induces peristalsis.
    2.  Another form of bowel movement may be called the pendulum movement.  This is a contraction and elongation of the longitudinal muscular layer which does not propel. the contents analward.  The lumen of the intestine remains the same.  The pendulum movement of the bowel is localized and limited to short stretches of intestine.
    3.  A third kind of bowel action is described by Professor Nothnagel as a roll motion.  Though recognizing Dr. Nothnagel's keen observing powers, I cannot see anything in the roll motion of the bowel except an excessive physiologic, or, better, a pathologic physiology process.  It is, in my opinion, only a wild or stormy peristalsis; when, for example, the blood contents, gas or fluid, go onward by spells or jerks.  The roll motion doubtless includes those peculiar gurglings which every individual now and then experiences.  And though this form of bowel motion is not accompanied by pain, yet it seems to border on the pathologic lines.  Of course almost all bowel motion of any distinct type belongs to the small intestines.  Perhaps one can scarcely ever observe the large bowel motion through the abdominal wall, if it be in a physiologic state.  Perhaps the roll motion of the bowel described by Nothnagel is due to an irregular action of the nerve supply, the movements of which, as Auerbach's plexus, may become disordered.  Formerly I thought that the large bowel did not share but a very small part in the excessive activity of blood motion, but recently I found a two-inch "invagination of death" in the ascending colon of an adult, so that the colon engages in a wild, disordered motion of death when the cerebrospinal system has lost control forever of the bowel motion (sympathetic).
    Peristalsis of the small intestines does not consist of waves starting at the duodenum and extending to Bauhin's valve, but the small peristalsis consists of local waves which start and cease within perhaps six inches to two feet.  One may recognize peristaltic waves in the same animal two to three or four feet apart, each going through its wave.  Now it appears that bowel contents cause the excitants of bowel peristalsis, and even if one observes a full bowel quiet, it does not necessarily overthrow the idea that bowel contents alone excite bowel peristalsis.  Empty intestines are still unless excessively stimulated.  We must look for the primary anatomical point of motive force of the bowel muscles in Auerbach's plexus.  Among the very unsatisfactory experiments are those attempting to find out the location of a nervous center for bowel movement.  Pflueger discovered that when the splanchnics are stimulated the bowel motion is prohibited, the bowels become pale and the blood-vessels become narrowed (anemic); but severing the splanchnics induces increased bowel peristalsis, the bowels become more filled with blood and congestion occurs.  Some assert one thing and some assert another in regard to the influence of the vagus over the intestinal motion.
Ludwig, Nasse, Kupffer, Mayer and Basch found in the splanchnic prohibitory and vaso-motor nerves, besides nerves which, by stimulation, irritated motion in the bowel.  Also Mayer and Basch could, by irritating the vagus, prohibit intestinal movement.  Basch and Erhmann believed from experiments that the splanchnics were the motor nerves of the longitudinal muscular layer and the prohibitory to the circular muscular layers, and that the vagus stirred up the circular muscles while it prohibited the longitudinal muscles.  Fellner claims that he found the nervi errigentes to be the source of longitudinal muscular action, while the hypogastric nerves were the motor nerves for the circular muscles.  Lately Steinach claims that the motor innervation of the intestinal tract is through the posterior sensitive roots of the spinal cord.  The portion of the colon supplied by the inferior mesenteric artery, i. e., the descending colon, sigmoid and rectum, have an analogous supply to the upper portion of the digestive tract.  The nerves from the spinal cord pass through the rami communicantes, through the lateral chain of sympathetic ganglia into the hypogastric plexus mesentericus inferior, which plexuses supply the sigmoid, rectum and descending colon.  The lumbar region was proven by Goltz's experiment to have a motor center for the rectum.  In this case the spinal nerves course through the hypogastric and mesenteric plexuses to act as motor nerves for the

     Fig 77.  The abdominal portion was accurately dissected from specimen under alcohol.

bowel.  The sympathetic nerves and ganglia, the unconscious motors of the assimilating laboratory, work steadily while the digestive tract has any contents.  It is entirely analogous to the uterus.  When there exist contents in the uterus its walls pass and repass through. constant waves, but if it is empty, it is quiescent, it is still.  So it is with the bowels, an empty intestine is still a quiet one; a full one is nearly always in motion.
    Anemia of the intestines lessens the peristalsis while hyperemia increases the peristalsis.  Chemically indifferent substances will create bowel motion according to their deviation from the normal bodily temperature.  It must be remembered that over distention makes contraction impossible, i. e., tympanites is paralysis just exactly according to its degree of distention.  Tympanites is accompanied by slight peristalsis but the pain is due to local spasm, especially of the circular muscles.  It appears to me that the circular muscles of the bowel can so obliterate the lumen that it practically prevents all passage of contents.  Doubtless the muscles would sooner or later tire out and admit of the passages.  We may say that it is extremely rare to observe the physiologic bowel peristalsis through the abdominal wall.  But it is not at all rare to observe the bowel peristalsis through the abdominal wall in a pathologic state.  In the normal state the abdominal wall is so thick, and the change of shape and form of the intestine is so slight that one can seldom definitely mark out bowel peristalsis.  In belly walls thinned by wasting disease and muscles thinned and separated by the stretching of the walls one may map out moving bowel coils very easily.  Especially is this the case in bowel obstruction.
    Peritalsis of a pathologic character may be (a) an increase of normal movement, (b) tonic contraction, or (c) the so-called antiperistalsis.  The rolling motion of the bowel described by Prof.  Nothnagel, I would call pathologic.  If one will open dogs with peritonitis there may be observed irregular bowel movements; sharp contraction of both longitudinal and circular muscles.  In fact the peristalsis has become irregular, excessive, wild.  The slow, normal, pendulum movements of dilatation and contraction of gut have been displaced by violent movements.  The bowel movement or peristalsis is accordingly violent and wild as the bowel wall is inflamed.  One may observe increased bowel peristalsis from (a) irritating foods, (b) from strong doses of physic, (c) in sudden mental disturbances, (d) in neurotic patients, (e) from hot or cold fluids, drinks or foods, (f) in enteritis or peritonitis, (g) especially in intestinal stenosis, (h) the absorption of lead into the system, (i) exposure to cold.  It did not appear to me that traveling of dogs increased the peristalsis, yet in general, motion aids to increase peristalsis.  The important tetanic bowel contraction is significant, for in experiment one can observe by pinching a piece of bowel it will contract into a pale white cord, perhaps entirely closing the lumen for all practical purposes.  The tetanic contraction slowly yields its spasm, but doubtless is accompanied with terrific pain.  For almost every drop of blood is driven out of the intestinal wall and the nerves are pressed in a traumatic state.  If neuralgia is a demand for fresh blood, surely this is a typical example.
    Doubtless in the violent pain of lead-colic (colica saturina) the intestine, is contracted to a white rod and the condition of persistent pain depends on various segments being successively attacked.  Tonic contraction of the intestine is a frequent condition of bowel stenosis.  If one will sit down by a patient with sufficient bowel stenosis to produce obstruction of the bowel contents, by placing the hand on the abdomen he can easily perceive the bowel movements, because in such patients the belly wall is usually thin.  The bowel movements are almost constantly felt, they gradually increase until the small intestine may f eel as hard as a rolling-pin under a sheet, and such a hard bowel will gradually relax, when the same phenomenon will appear elsewhere.  It is quite probable that progressive peristalsis is not accompanied by pain, no matter how lively it is.  But tonic or spasmodic contraction of the bowel can be and is accompanied by the most sickening pain.  The chief pain from the bowels (colic) no doubt arises in disturbed or disordered peristalsis.
    Local inflammation in the intestine producing an irritability of the peripheral nerves, induces irregular, disordered and wild bowel contractions with severe pain.  Much has been said by writers in regard to antiperistalsis, i. e., peristaltic wave directed toward the pylorus instead of toward the anus.  I have studied this subject considerably in an experimental method, but have never been able to see distinctly anything but very irregular antiperistaltic waves.  I tried Prof.  Nothnagel's claims that sodium salts made antiperistalsis, and that potassium salts induced peristalsis, but after several trials on dogs to test the direction of the intestine I could not consider it of any practical value, neither could I confirm his assertions.  After laparotomy we frequently observe considerable pain. and almost always accompanying this pain there is more or less tympanites.  The pain is due to irregular contraction of the intestinal wall.  Segments of the bowel become over-distended, which is a kind of partial paralysis and it cannot again contract.  This distended portion does not give pain.  The pain arises from the non-distended or partially distended segments which are in a state of spasm, irregular contraction and with irritable peripheral nerves.
    Excessive or irregular bowel peristalsis is observed among hysterical and neurasthenic persons.  It is recognized by gurgling, splashing or rumbling noises in the abdomen.  It arises in neurotic persons, yet the same person generally suffers no unpleasant sensations, except the mental annoyance.  The rumbling noise has no especial connection with mealtimes or drinking.  If it occurs in women it is apt to be more active at the menstrual time.  Mental influences seem to play a role, for when the subject works or directs the mental energies away from the phenomenon, the gurgling generally ceases.  If the abdominal walls be thin, one can observe the intestinal movements, which are confined chiefly to the small intestines.  Other subjective symptoms generally fail; however, gas may be belched.  The diagnosis of excessive bowel peristalsis is not difficult if one can observe the patient for some time.  The trouble may persist for weeks and normal stools continue during the whole time.  Excessive bowel peristalsis may be diagnosed from bowel stenosis by its spontaneous appearance and cessation.
    It seems a characteristic of certain persons to have repeated attacks, and I have observed such attacks for many years in certain persons at certain times, when the mental faculties were either on a sudden tension or embarrassed.  It is reported that an old and valuable servant felt obliged to give up waiting on account of repeated attacks of loud gurgling when she was serving at mealtimes.

     Fig. 78.  The dilated hepatic ducts impress with the idea of the quantity of nerves attending the ducts in the form of a nodular, fenestrated, anastomosing plexus ensheathing the channels.

    Excessive peristalsis is generally confined to the small intestines.  The treatment of excessive bowel peristalsis should be both physical and mental.  Hydrotherapy, massage, galvanization of the abdomen and remedies profoundly affecting the olfactory nerve, aid to bring about normal bowel peristalsis.  As remedies the bromides, arsenic, iron and nux vomica are valuable adjuncts.  The regulation of the diet is of first importance.
    Enterospasm is a condition of the bowel in which the longitudinal or circular muscular layers are in a state of excessive contraction.  To see an actual demonstration of this phenomenon, the most practical method is to open a rabbit's or a dog's abdomen and by pinching the bowel wall with the finger and thumb both the muscular layers will be observed in a state of spasm.  The circular muscular layer on being pinched or struck will contract to a small white ring or band.  The enterospasm is likely to occur in very limited segments of bowel.  If it be primary, it is a motor impulse, but it may be secondary to a sensory neurosis when it is of a reflex nature.  In such a case both a motor-neurosis and a sensory-neurosis exists, that is, a mixed neurosis.
    Enterospasm is primarily a motor-neurosis, but is frequently combined with reflex sensory factors inducing severe pain.  As a result of the spasm irregular constipation arises.  The stool is either long retained or forcibly expelled.  Enterospasm may owe its origin to misuse of cathartics, the entrance of lead into the system, mental effects, worms or improper use of foods.  Meningitis or disease of the cerebrospinal axis may play a role.
    The treatment of enterospasm consists of opium and evacuants.  It is this form of constipation that the old physicians said, paradoxically, opium cured.  It cured the spasm and the bowels naturally become regular.  The proper treatment, however, will consist more in diet regulation, colonic flushings, in electrical treatment, in bromides, nux vomica, in massage and hydrotherapeutic measures.
    Paralysis of the bowel signifies that the contents are not forced onward, though the lumen is patent; no mechanical obstruction exists.  Henrot announces three forms: We first have direct paralysis of the bowel from affection of its walls, as after reduced hernia; often trauma, as in laparotomy, after peritonitis, enteritis, etc.
    Second we have indirect or reflex paralysis, as from injury to the testicle; inflammation of a bowel segment, as inflammation of the appendix, produces paralysis of large bowel segments, the irritation being reflected to the abdominal brain, reorganized and sent out on the various nerve plexuses, laming the said segments.  An abscess in the abdominal wall may by reflex action produce paralysis of a bowel segment sufficient to prevent the onward movement of the feces.  In many autopsies, experiments on animals or on humans, I have noted where a small perforation had produced paralysis of adjacent segments by spread of peritoneal inflammation.  No mechanical obstruction existed.  This is what one continually hears of as obstruction of the bowels - it is really peritonitis.  The paralysis is due to edema and exudates pressing on the peripheral nerve apparatus of the bowel wall.
    Thirdly, by leaving out of consideration the cerebrospinal lesions we have bowel paralysis from hysteria, melancholia, neurasthenia, from atony of the bowel and from persistent coprostasis.  It must be remembered that the symptoms of ileusparalyticus are not easy to diagnose from genuine ileus.  In genuine ileus the peristalsis of the bowel is increased on the proximal side of the affected locality.  The therapeutic application for any form of ileus depends entirely on the original cause.  Should the paralysis depend on some neuroses, the treatment will be regulation of diet, electricity and massage of the abdomen, the careful use of evacuants and moral influences.  Colonic flushings are excellent in this form of neurosis.
    Deficient peristaltic action observed in old age and anemic persons depends, perhaps, much on exhaustion, and deficient blood of a proper composition.  Besides, deficient peristalsis means deficient secretion, and deficient secretion means an empty bowel, and an empty bowel means a quiet one. The parenchymal intestinal ganglia require proper blood to stimulate them to action.  The peristaltic movements of the bowels are anatomically excited by the distal visceral ganglia, yet they receive and empty feces from the abdominal brain impulses to accelerate or retard the bowel motion.

     Fig. 79.  Illustration of nerves from my own dissections.

    McKendrick believes the accelerating nerves of the bowel are from the sympathetic ganglia, while the prohibiting nerves are from the lumbar spinal.  The descending colon and rectum, according to Nasse, receive motor fibers from the plexuses of nerves surrounding the mesenteric artery.  The general notions (Fox, McKendrick, Nasse, Bridge, Kolliker) are that the gastrointestinal ganglia send motor fibers to the bowel muscle and that these automatic ganglia are stimulated reflexly by fibers running from them to the mucosa (Henle).  Hence, a diarrhea is a reflex matter.  Pflueger believed that the splanchnics were inhibitory nerves of bowel action, but Basch showed that the splanchnics were inhibitory nerves only in a secondary manner by changing the circulation in the bowel.  The motus peristalticus in lead colic is of much interest, as it should lead to the source of bowel motion, but the special action of lead on tissue is not yet settled.  However, it belongs without doubt to the abdominal sympathetic.  Is the disturbance due to the action of the lead on the sympathetic ganglia? Does the lead act as an excitant on fibers of the splanchnics?  Both views may be retained until more precise data exist.  Begbie asserts that irritation of the abdominal brain (or, as he says, plexuses surrounding the aorta) induces active movements of the small intestines and colon.  Valentin discovered that irritation of the fifth nerve produces invariably movements of the small intestines.  We must remember that the fifth nerve is par excellence the ganglionic cranial nerve, having eight ,ganglia situated on its branches.  It is really a sympathetic cranial nerve.  It is not yet clear what is the influence of the cerebrospinal system over the movement of the abdominal viscera, but observers are agreed that fear, fright, emanations, intensely influence the bowel movements, showing the influence of the cerebrospinal axis on the bowel and sphincters.  How much is this due to relaxation of sphincters?  As Romberg remarked fifty years ago, the field of influence of the cerebrospinal axis over bowel movement is not fully known.  From personal experience we know that ordinarily the passing form of colic, bowel spasm, is due to irritating contents.  The irritation of the mucosa passes to the automatic ganglia of the bowel wall, which resents the trauma by muscular contraction; the consequence is pain.
    The motor bowel, automatic parenchymatous ganglion, is one of the best samples to illustrate the highest degree of independence.  The influence of the sympathetic nerve upon the intestines has long been recognized.  The long controversy in relation to the influence of the great splanchnic nerve upon the small intestines seems to be more definitely settled.  Weber showed some years ago, that the splanchnic exerts an inhibitory action upon the intestines, arresting their movement.  Legros and Onimus, however, claimed to show by their experiments that the splanchnic is, on the contrary, the motor nerve of the intestines, and, when stimulated, produces contraction of the intestinal walls.
Recent experiments made by Coutade and Guyon present very clear evidence that the two muscular layers of the intestine are controlled by nerves of a different origin, the circular layer being controlled by branches of the sympathetic, and the longitudinal by the spinal nerves.  The conclusions arrived at by these investigators are as follows, to which all experimenters do not agree:
    1.  The sympathetic causes contraction of the circular muscular layers of the intestine and, at the same time, relaxation of the longitudinal muscular coat.
    2.  The contraction of the small intestines depends entirely upon the sympathetic, and is wholly independent of the pneumogastric.
    Galvanization of the abdominal brain induces active movements of the small intestines and, to a certain degree, of the large.  Anatomic and physiologic experiments certainly show that branches of the abdominal brain take part in the innervation of the stomach.
    There is a certain kind of excessive bowel peristalsis which is disastrous at any age, but especially in infancy.  I refer to invagination.  One-quarter of all invaginations occur before one year of age, and one-half of invaginations occur under ten years of age. Invagination, telescoping, intussusception, is where one segment of bowel is driven into the adjacent one.  Nearly all invaginations are toward the anus distalward, but some report invagination toward the stomach proximalward.  Hektoen reports a case of proximalward invagination.  Invaginations are especially likely to arise in two classes of subjects, viz.: (a) in children and (b) in persons dying of some cerebrospinal trouble.  The invaginations found in autopsies may be called the invagination of death.  I have repeatedly found this condition in human and animal autopsies.
    The characteristics of the invagination of death are that they are accompanied by no inflammatory process, no exudates, no congestions or peritonitis, and are often multiple.  In one dog, dying of peritonitis, I found four points of invagination close to each other.  They were invaginations of about an inch distance each.  Several times in human autopsies, I have found from one to four points of invagination.  The characteristics of ordinary invagination are that it is accompanied by severe and sudden pain and, if continued long enough, by congestion, exudation and inflammation in the bowel tunics.  Finally, the apex will begin to bleed and slough, producing bloody stools and finally peritonitis; and its results are found about the point of invagination.
    Invagination is due to irregular action of the muscles in the intestinal wall.  It is due to irregular peristalsis.  In children and persons with diseased cerebrospinal systems it appears that the cerebrospinal axis, the higher nerve center, has lost its normal control over the sympathetic, which rules the bowels, and the result is that the intestines assume wild and disordered movements.  Not only the bowel segments but their longitudinal and circular muscles begin to act without harmony, irregular, spasmodic.  In infants and children it appears that the cerebrospinal axis has not assumed full control over the sympathetic which rules the bowel muscles.  Since invagination constitutes one-third of all forms of intestinal obstruction, regular action of the gut wall assumes an important role.  It is curious to note the common localities of invagination.  The ileo-colic and ileo-cecal constitute 50 per cent, i. e., 50 per cent of invaginations occurs at the ileo-cecal valve.  Thirty per cent occur in the small intestines and 20 per cent occur in the colon.  Omitting the region of the iteo-cecal valve as having some mechanical peculiarity tending to invagination, we note that there are more invaginations in the small intestines than in the large. which must be due to a greater possession of muscles.