The Abdominal and Pelvic Brain
Byron Robinson, M. D.
THE VASOMOTOR INTERILIAC PLEXUS
(PLEXUS INTERILIACUS VASOMOTORIUS-SYMPATHICUS).
Immaterial, irrelevant, incompetent. - Attorney's objection to evidence
in law trials.
Industry wins living, honesty wins respect.
Extending from the abdominal brain (the coeliac axis)
to the pelvic brain (cervico-uterine junction) there exist two rich and
mighty nerve plexuses, plexus aorticus and plexus interiliacus.
For convenience of description and significance
in practice I will divide this plexus into two grand divisions, viz.:
(a) The plexus aorticus extending from the
coeliac axis to the aortic bifurcation; (b) the plexus hypogastricus
or more significantly plexus interiliacus, which extends from the bifurcation
of the aorta (sacral promontory) to the junction of uterus and vagina.
The plexus interiliacus is important because it is the great highway of
travel for afferent (initiative or spontaneous) and efferent (reflex peripheral)
genital nerve forces. I shall view the plexus interiliacus as originally
belonging and accompanying the common iliac vessels. However, by
erect attitude, distalward movements of the tractus genitalis and increasing
dimensions (especially lateralward) to the pelvis, coalescence of the proximal
extremities of the two branches of the plexus interiliacus arose.
That is, the original nerve plexuses accompanying the common iliac arteries
gradually moved medianward from them. Hence the term plexus interiliacus
is particularly appropriate. The plexus interiliacus has experienced
a variety of names during the past two centuries.
Synonyms: Superior hypogastric plexus (plexus hypogastricus
superior, Tiedemann, 1822). Medial hypogastric plexus (plexus hypogastricus
medius). Impar (odd, single, impaired) hypogastric plexus (plexus
hypogastric impar). Interiliacal plexus (plexus interiliacus, Waldeyer,
living). The great uterine plexus (plexus uterinus magnus, Tiedemann,
1822). Pelvic plexus (plexus pelvicus, Thomas Snow Beck, 1845, 1814,
1847). The hypogastric ganglion, i. e., layer (lamina gangliosa hypogastrica,
Gabriel Gustave Valentine, German anatomist, 1810-1883). The common
uterine plexus (plexus uterinus communis, Tiedemann, 1822). Iliac
plexus (plexus illacus-anatomica nomina, Basel). Distal part of the
aortic plexus (plexus aorticus distal, Henle-Fred Gustav Jacob Henle, German
The plexus interiliacus I shall consider under three
distinct headlines, viz.: (a) interiliacal nerve disc (proximal end); (b)
trunk of the plexus interiliacus (central segment); (c) pelvic brain (distal
end or ganglion cervicale).
(a) INTERILIAC NERVE DISC.
The proximal end of the plexus interiliacus, which
I shall term the interiliacal nerve disc of the sacral promontory, is practically
a plexus of nerve cords compressed or flattened dorso-ventrally.
The interiliacal disc is the result of coalescence of the distal end of
the plexus aorticus, located at the aortic bifurcation, practically on
the sacral promontory and the distalward movements of the tractus genitalis
producing traction and extension on the nerve disc of the sacral promontory.
The interiliac nerve disc is practically a plexiform nerve mass located
at the proximal end of the plexus interiliacus. The arrangement of
the interiliacal disc consists in the coalescence on the same promontory
of the afferent nerve-plexus aorticus and branches from the distal bilateral
lumbar ganglia - and the emission of efferent nerves: (a) two bilateral
large plexuses to the pelvic brain; (b) branches to the tractus intestinalis
(rectum hoemorrhoidal); (c) branches to the tractus genitalis (uterus,
vagina, oviduct); (d) branches to the tractus urinarius (ureter, bladder).
II. Holotopy (relation to general body).
The interiliac nerve disc is located on the median line in the space between
the major bifurcation and the distal end of the abdominal end cavity immediately
proximal to the lesser pelvis. It is a coalesced unpaired organ situated
extraperitoneally on the sacral promontory, dorsal to the peritoneum.
It is strongly ensconced in connective tissue at the most accessible portion
of the abdomen for palpation.
II. Skeletopy (relation to osseous system).
The interiliac nerve disc lies on the ventral surface of the distal lumbar
and proximal sacral vertebrae. It lies practically on the brain of
the inner osscous pelvis.
III. Syntopy (relation to adjacent viscera).
The interiliac nerve disc, coalesced (unpaired), is located centrally in
the space between the major aortic bifurcations which practically includes
the ventral surface of the two distal lumbar and two proximal sacral vertebrae.
It is securely ensconced in strong dorsal subperitoneal connective tissue.
It is situated between the peritoneum and pelvic fascia. The interiliac
nerve disc is limited to the space between the coalescence of the plexus
aorticus (aortic bifurcation) and the emission or divergence of the plexus
interiliacus (second sacral vertebrae). The interiliac nerve disc
lies dorsal to certain changeable mobile loops of the enteron and mesenteron
and possess variable relations to the sigmoid and mesosigmoid. In
peritonotomy, in spare subjects, the interiliac nerve disc may be observed
shimmering whitish through the dorsal peritoneum.
IV. Idiotopy (relation of the component segments).
The interiliac nerve disc consists of a nerve plexus compressed, flattened,
dorso-ventrally, and interspersed with fenestra of varying number and dimension.
The fenestra increase in number and dimension from proximal to distal borders.
Dimensions: The interiliacal disc is some two inches in length and
three fourths of an inch in width. Form. The form is that of truncated
cone. The lateral borders are bounded by nerve cords. The proximal
border fuses with the plexus aorticus. The distal border coalesces
with the emerging efferent lateral interiliacal plexuses.
GENERAL REMARKS IN REGARD TO THE INTERILIAC NERVE DISC.
It consists of a flattened, band-like nerve plexus
in a sheath of firm, dense, connective tissue, located in the interval
between the two common iliac arteries. It is formed by a continuation
of the plexus aorticus plus prolongations from the ganglia lumbales.
It is a flat plexiform nerve mass at the junction of the distal lumbar
and proximal sacral vertebrae. I have termed it the interiliac nerve
disc, as it contains no constant distinct ganglia. Some authors claim
it contains no ganglia, while others claim it contains some ganglia, the
latter being the more probable. The interiliac disc is significant
as it emits (efferent nerves) from its distal border, the two nerve plexuses
which rule the pelvic viscera. The interiliac nerve disc is
an example of the principle elsewhere noted that at every emission of a
major (visceral) artery from the abdominal aorta there exists a ganglion
(or nerve disc). Practically there should be two ganglia at the aortic
bifurcation. However, coalescence occurred and one ganglion or disc
resulted - the interiliac nerve disc (or ganglion). Efferent nerve
branches from the interiliac disc not only accompany the two common iliac,
ovarian, superior haemmorhoidal and sacral arteries but emit the two great
interiliac plexuses (for the pelvic viscera) as well as branches to the
ureters, left colon and sigmoid. The interiliac nerve disc is important
in practice because it is practically accessible to manipulation, massage.
By gentle irritation or massage of the interiliac disc in post partum hemorrhage
the plexus interiliacus will be stimulated, which, supplying the uterus,
will induce the elastic and muscular bundles of the myometrium to act like
living ligatures, limiting the uterine vessels, and checking haemorrhage.
It is not the supposed constriction of the aorta that checks the haemorrhage.
(b) TRUNCUS PLEXUS INTERILIACUS SYMPATHICUS.
The trunk or central segment of the interiliac plexus
(paired) extends from the interiliac nerve disc to the pelvic brain.
The plexus interiliacus consists not merely of nerve strands, for it is
composed of nerve plexuses the commissures and cords of which are band
or ribbon-like in character surrounding apertures or fenestra of various
dimensions which increase in area toward the distal end. The plexus
interiliacus increases in breadth from proximal to distal end, i. e., from
interiliac nerve disc to pelvic brain. The proximal end is relatively
small and composed of a few nerve cords, the distal end is broad and divides
into numerous branches. The course of the interiliac plexus is proximally
along the internal side of the pelvic vessels while distally it courses
along the dorsal and rectal wall with which it is intimately connected
by connective tissue and, when it again resumes intimate association with
the pelvic vessels the length of the trunk of the plexus interiliacus averages
some 3 ½ inches. Numerous nerve branches from the V lumbar
ganglion and from the I, II, III and IV sacral ganglia join the external
border of the plexus interillacus. From the internal border of the
plexus interiliacus numerous branches pass to the rectum, ureter, uterus,
vagina, bladder. From the plexus pass numerous nerves to the pelvic
vessels. The trunk of the plexus interiliacus is profoundly associated
with the rectal wall, sharing in its movements or contraction of and dilatation.
The intimate and profound connections of the trunk of the plexus interiliacus
with the rectal wall explains the favorable therapeutic value of the rectal
enema due to stimulation of the plexus. The rectum is practically
surrounded, ensheathed by two great bilateral interiliac plexuses, i. e.,
the rectum lies in the boot-jack angle produced by the divergence of the
plexuses. The plexus interiliacus possesses a remarkable anatomic
feature, which is that it sends some two strong nerves directly to the
uterus without first passing through the pelvic brain (demonstrated with
very extraordinary facility in infant cadavers).
(c) DISTAL END OF THE PLEXUS INTERILIACUS OR PELVIC BRAIN.
The broad distal end of the plexus interiliacus,
a plexiform fenestrated nerve mass, unites with the branches of the II,
III and IV sacral nerves to form the pelvic brain (ganglion cervicale).
The resulting union of the distal end of the plexus interiliacus and sacral
nerves - a plexiform ganglionated mass, the pelvic brain - rules the physiology
of the pelvic viscera, especially the vascularity of the genitals.
The pelvic brain is elsewhere described in detail.
GENERAL REMARKS ON THE PLEXUS INTERILIACUS.
The plexus interiliacus, like the plexus aorticus,
is one of the great and important nerve plexuses of the abdomen.
It practically supplies the tractus genitalis; distal end of tractus intestinalis
(rectal, sigmoid) ; and distal end of tractus urinarius (ureter, bladder).
The plexus interillacus is double, bilateral, presenting practically no
anastomosis. It is accessible to manipulation through the abdominal
wall as well as per rectum and per vaginam. Dilatation of the rectum
produces its favorable therapeutic effects through the plexus interiliacus
by flushing the capillaries and stimulating visceral function, especially
respiration. The plexus interiliacus is the dominating plexus of
the pelvis. It is the great assembling nerve center of the pelvic
organs and is solidly and compactly bound and anastomosed to all other
pelvic sympathetic nerves as well as the I, II, III and IV sacral spinal
nerves. The following table presents an idea of the vast extent and
richness of distribution of the branches of the plexus interiliacus.
It should be remembered that the vast majority of the branches of the plexus
interiliacus first pass through the pelvic brain before supplying the pelvic
viscera (especially those to the tractus genitalis).
1. Tractus Intestinalis (haemorrhoidal)
a. colon (left)
2. Tractus Genitalis
3. Tractus Urinarius
4. Tractus Vascularis
arterial plexuses accompanying
all pelvic arteries
5. Tractus lymphaticus
(all pelvic lymphatic glands are richly supplied),
A peculiar character of the plexus interiliacus is
that it is considerably disassociated from arterial vessels - unlike the
plexus aorticus. The pelvic visceral plexus or branches of the plexus
interiliacus possess similar features. On the contrary, the visceral
plexuses or branches of the abdominal brain notably accompanying the visceral
AGE RELATION OF THE PLEXUS INTERILIACUS.
The plexus interiliacus experiences an age relation
according to the sexual phases as presented by the utero-ovarian artery
in: (a) pueritas, (childhood), a quiescent, undeveloped state with limited
blood, ganglion cells and neurilemma; (b) pubertas, a developmental state
(of congestion) of multiplication of ganglion cells and increased neurilemma;
(c) menstrual phase, a functional state of engorgement (of the vaso uterina),
which further increases the neurilemma if not the ganglion cells; (c) gestation,
a state of complete development of the tractus genitalis (continuous maximum
engorgement of the utero-ovarian artery) with the multiplication of ganglion
cells and periganglionic tissue with neurilemma; (d) puerperium.
The elastic and muscular bundle of the myometrium having contracted like
living ligatures, the enormous volume of blood passing through the utero-ovarian
artery is checked, maximum engorgement suddenly ceases, the ganglion cells
perhaps remain the same in number, however, decreasing in dimension; while
the periganglionic tissue, the neurilemma and associated connective tissue
decrease, degenerate; (e) climacterium. This phase of sexual life represents
beginning atrophy from lessening of blood volume in the utero-ovarian artery.
The ganglion cells diminish in size and number as well as the periganglionic
tissue, while the associated connective tissue multiply; (f), senescence.
This is the atrophic sexual phase - death of parenchymatous and increase
of connective tissue framework of viscera. The muscularis and elastic
fibres of the myometrium and oviduct decrease while the connective tissue
increases. The wall of the utero-ovarian artery increases in thickness
while the lumen decreases in dimension. The ganglion cells of the
plexus interiliacus decrease in number and dimension while the ganglion
cell, nucleus and body cell outlines become less distinct.
The periganglionic connective tissue and neurilemma
decrease while the associated connective multiplies. In senescence
the plexus interiliacus, which was originally destined for the tractus
genitalis, gradually fades from its maximum dignity of structure and function.
Senescence has returned the plexus interiliacus to its primitive phase
of pueritas or quiescent existence.
UTILITY OF THE PLEXUS INTERILTACUS IN PRACTICE.
It is accessible to manipulation from proximal to
distal end through the abdomen, per rectum or per vaginam. Massaging
or stimulating the plexus interiliacus induces the muscular and elastic
bundles of the organ which it supplies to contract by controlling the blood
volume. The most typical example for the employment of therapeutics
on the plexus interiliacus is during postpartum haemorrhage. It is
the irritation, massage of the plexus interiliacus, that induces muscular
and elastic bundles of the myometrium to contract and consequently control
the hemorrhages. It is not the obstruction produced in the aorta
by the pressure, the technique of which is almost impossible, for the two
ovarian arteries would still continue to force large volumes of blood to
the uterus. Light abdominal stroking, digital manipulation of the
uterus in postpartum hoemorrhage irritates, massages the plexus interiliacus
and its branches, which induce the elastic and muscular bundles of the
uterus to contract like living ligatures on the blood vessels, checking
haemorrhage. The so-called uterine inertia of long, tedious labor
may be due to paresis of the plexus interiliacus from trauma by the child's
head. Sudden cessation of parturient peristalsis - arrest of labor
- is doubtless due to trauma by the child's head on the plexus interiliacus,
a sudden paresis. Vaginal or rectal injections (hot or medicated)
stimulate the plexus interiliacus, hastening labor. Electricity will
accomplish similar effects. The flat, band-like form of the plexus
interiliacus protects it from trauma during parturition. Massage
of the plexus interiliacus will end all alleviating constipation by stimulating
active peristalsis and secretion of the left colon, sigmoid and rectum.
The plexus interiliacus may be stimulated by means of hot fluid or food
taken, in the stomach. The irritation passes from the stomach over
the plexus gastricus to the abdominal brain, whence it is reorganized and
emitted over the plexus interiliacus, inducing more vigorous uterine contractions.
By appropriate systematic massage of the plexus interiliacus stimulation
of the pelvic viscera may be effected, resulting in a vigorous circulation.
Fig. 9 This illustration presents
the sympathetic nerves following the arteries. I dissected this
specimen (man 40) with care, and the artist, Mr. Klopper, sketched exactly
from the model. 1 and 2, abdominal brain. Pn, Pneumogastric nerve;
sp. Nervus Splanchnicus major. Ad, adrenal; Dg, ganglion diaphragmaticum;
Adn, 10 adrenal nerves (right), (left), 7. G. R. arteria renalis (right
and left partially duplicate). N. Ganglia renalia (left).
Ur, ureteral nerves. S. G. and 5 upper ganglia spermatica. 1, ganglion
mesentericum inferior; X, ganglionic coalescence of nerves at the vasa
spermatica and ureteral crossing. 5 ganglionic coalescence of the nerves
at the crossing of the ureter and vasa iliaca communism IB, Plexus interiliacus
(hypogastricus) surrounding the rectum. ID is the fenestrated nerve
disc of the sacral promontory. V, Vena cava emitting the vena ovarica
on which is ensheathed the plexus ovaricus.
PLEXUS INTERILIACUS OF ADULT
Fig. 10. This specimen I
dissected with care under alcohol. The plexus interiliacus extends
from the discus interiliacus (D) to the pelvic brain (A). Observe:
(1) Two nerve strands are emitted from the interiliac plexus to the uterus
previous to passing through the pelvic brain (A). (2) Note the contribution
of the lateral sacral chain of ganglia and II and III sacral nerves to
the plexus interitiacus. 3) Bear in mind the intimate relation of the
plexus interiliacus to the rectum proximalward and distalward.
|Fig. 11. I dissected this
specimen in 1894 from a spare subject having enormously large vasomotor
nerves. The aorta divided into the iliacs at the junction of the III
and IV lumbar vertebrae. 112, genital ganglion; 173, third lumbar ganglion
(R) ; 114, genito-rectal ganglion; 103, lumbar lateral chain of ganglia;
173, third lumbar nerve ; 90, lumbar nerve; 91, lumbar nerve; 179, fourth
lumbar ganglion (R) 104, lateral chain of ganglia; 181, com. iliac artery
arising in this case at third lumbar vertebra; 188, inferior renal ganglia;
174, fourth lumbar nerve (.R); 189, fifth lumbar ganglion (R); 93, lumbar
nerves; 114, genital ganglion; 115, hypogastric plexus; 134, first sacral
ganglion (L) ; 179, fourth lumbar ganglion (R); 116 hypogastric plexus;
125, lumbo-sacral cord; 135, first sacral ganglion (R) ; 136, genital ganglion;
118, hypogastric plexus; 126, first sacral nerve (L); 170, lumbar
sacral cord; 130, first sacral nerve (R) ; 158, right sacral plexus; 137,
second sacral ganglion; 117, hypogastric plexus; 156, rectum; 127, second
sacral nerve (L). From author's life-size chart on the sympathetic
PLEXUS INTERILIACUS OF ADULT
Fig. 12. This specimen I
dissected under alcohol. D, interiliac nerve disc. Interiliac
iliac nerve disc (D) to the pelvic brain (A). Observe: (1) that
two large nerve stands are emitted from the interiliac plexus to the uterus
without first passing through the pelvic brain. (2) The plexus interiliacus
is intimately associated with the rectum. (3) The lateral sacral
chain of ganglia and sacral nerves contributes branches to the interliliac
The II, III, IV and V sacral nerves contribute
to form the pelvic brain, while in some specimens the I sacral nerve contributes
a branch or branches.