CHAPTER IX.

THE NERVES OF THE GENITAL TRACT 
(NERVI TRACTUS GENITALIS) - (A) ANATOMY, (B) PHYSIOLOGY.

The origin of genital nerves are: I, nervus vasomotorius (sympathetic-abdominal brain); II, spinal cord (medulla spinalis), through rami communicantes and rami nervorum sacralium (II, III, IV), cerebrum (vagi). 
The three major nerve streams to the tractus genitalis are (a) the plexus interiliacus (which is a continuation of the plexus aorticus) originating in the abdominal brain; (b) the plexus ovaricus originating from the whole plexus aorticus; (c) plexus sacralis spinalis (rami nervorum sacralium - II, III, IV). The minor nerve streams to the tractus genitalis are: (d) lateral lumbar ganglia (truncus nervus lumbales vasomotorius); (e) lateral pelvic ganglia (truncus nervus pelvis vasomotorius); (f) nerves of the uterine artery (nervi arteriou uterinae); (g) nerves of the hypogastric artery (nervi arteriac bypogastricac) richly demonstrated in infant cadavers. Also nerves of the round ligament and hemorrhoridal arteries. 
Practically the nerves supplying the tractus genitalis are solidly and compactly anastomosed connected with the whole abdominal vasomotor nerves (sympathetic), especially with the giant ganglion coeliacum - the abdominal brain - the great assembling center of the vasomotorius abdominale or sympathetic nerve plexus. The anastomosis or connection of the genital nerves to the nervus vasomotorius (sympathetic) and cerebro-spinal is vast and profound. The order of solidarity or compactness of anastomosis or profundity of connection of the vasomotor nerves (sympathetic) to the abdominal viscera is the following, viz.: (A) nervus vasomotorius to the tract - is vascularis (blood and lymph vessels); (B) nervus vasomotorius to tractus intestinalis; (C) nervus vasomotorius to tractus genitalis; (D) nervus vasomotorius to tractus urinarius. However, all the abdominal viscera are solidly and compactly aliastomosed, connected to the central abdominal sympathetic or vasomotor nerve that no one visceral system can become disturbed, deranged, without affecting profoundly all other visceral systems. The derangement arising in the several abdominal visceral systems caused by irritation or disease in any one abdominal visceral system is produced by reflexes, resulting in the disturbed common visceral function - peristalsis, secretion, absorption, sensation. So far as I am able to observe, the reflexes, or irritation in the tractus genitalis produces the most profound and vast derangement of function in other abdominal viscera of any single visceral system, e.g., irritation, disease in the tractus genitalis, passes to the abdominal brain (over the plexus interiliacus and plexus and plexus aorticus) where it is reorganized and emitted to the tractus intestinalis or tractus urinarius, deranging the common function of peristalsis (rhythm), secretion, sensation and absorption - causing deficient, excessive or disproportionate peristalsis, secretion or absorption. The older anatomists, like the philosophic Willis (1622-1675), who was the Sedlian professor in Cambridge, claimed that the nerves supplying the tractus genitalis arose from the intercostal nerves, that is, by means of the rami communicantes, truncus vasomotorius - lateral ganglionic chain and nervi splanchnici. This is as true today as in the days of the ever-memorable Willis; however, we ascribe today more to independent, more differentiation to the vasomotor nerves (sympathetic) than did Willis. These so-called intercostal nerves (rami communicantes) form a nervous center - the abdominal brain - secondary to the cranial brain, which has differentiated functions of the first magnitude as regards existence of life itself. Hence, today we are inclined to believe from experimentation and clinical data that the chief origin of the nerves of the tractus genitalis is the abdominal brain - cerebrum abdominale, and since this giant ganglion controls the vascular supply of the abdominal viscera it should be termed cerebrum vasculare abdominale. In the consideration of the nerve supply of the tractus genitalis it is favorable for convenience of description and practical purposes to present a major and minor nerve stream. The following table presents in a bird's-eye view the major and minor nerve supply to the genital tract:

Major Nerve Supply. 
A. Plexus interiliacus (sympathicus). 
B. Plexus ovaricus. 
C. Plexus sacralis spinalis (rami nervorum sacralium).

Minor Nerve Supply 
D. Lateral lumbar ganglia (truncus nervus sympathicus lumbales). 
E. Lateral pelvic ganglia (truncus sympathicus sacrales). 
F. Nerves of the uterine artery (nervi arteriee uterin2e). 
G. Nerves of the hypogastric artery (nervi arteriae hypogastricee). 
H. Nerves of the round ligament artery (nervi arteriae ligamenti rotundi).

I. Nerves of the haemorrhoidal artery superior et medius (nerve arteriae hemorrhoidalis superior et medius). I 
The major nerve supply consists of (A) plexus ovaricus; (B) plexus interiliacus (vasomotorius); (C) plexus sacralis spinalis rami nervorum sacralium (II, III, IV).

...........The interiliac plexus extends from the interialic nerve disc to its union with the sacral nerves of the cervico-vaginal junction. It is the major nerve supply of the genitals. it is elsewhere described in detail.

(C) Plexus Sacralis Spinalis (Rami Nervorum Sacralium). 
The second, third and fourth sacral, spinal nerves emit branches (pelvic splanchnics) which join, coalesce, with the distal branches of the interiliac plexus to form the pelvic brain (ganglion cervicale - which issues the white rami communicantes) practically the plexus uterinus, plexus vesicalis, plexus rectalis, plexus vaginalis, plexus clitoridis, plexus pudendalis. The spinal sacral nerves passing to the pelvic brain gave rise to the idea that they supplied the cervix uteri, and that they are sensory nerves of the uterus. So far as I have been able to observe, all branches of the sacral spinal nerves first enter the pelvic brain before passing to the uterus and vagina. One nerve from the second sacral passes directly to the bladder without first passing through the pelvic brain. The branches of the sacral nerve passing to the pelvic brain vary in number, origin, arrangement, length, and dimension. They are the most accurately demonstrated in infant cadavers preserved in alcohol. The blending or coalescence of the branches of the sacral nerves (pelvic splanchnics) ( I to IV) with the distal branches of the plexus interiliacus (vasomotorius) results in the pelvic brain - a plexiform, multiple, nodular ganglionic nerve mass located where the rectum joins the cervicovaginal junction, and being of irregular form, dimension, weight. The pelvic brain is practically the source of the genital nerves. The minor nerve supply of the tractus genitalis consists of D, E, F, G, H, I.

(D). The lateral lumbar trunk ganglia send nerves to the plexus aorticus and plexus interiliacus.

(E). The lateral pelvic trunk ganglia send nerves to the genitals by way of the pelvic brain. It sends nerves to the distal ureter.

(F). The nerves accompanying the internal iliac artery continue their course over the arteria uterine as the nervi arteriae uterinae.

(G). The nerves of the hypogastric artery (nervi arteriae hypogastricae) carries larger numbers of nerves to the genitals in the infant. It also emits branches to the ureter and bladder. With atrophy of the hypogastric artery many nerves fade with the artery.

(H). Nerves of the round ligament artery (nervi arteriae ligamenti rotundi) pass from the external common iliac artery to join with the plexus ovaricus and plexus uterinus.

(I). Nerves of the hemorrhoidal artery superior and medial (nervi arteriae haemorrhoidalis superior et medius) emit nerves to the genitals. It will be observed that the major and minor nerve supply of the genitals is so extensive, so solidly and compactly anastomosed that severing the genital nerves for experimentation is incompatible with life, and consequently reports of such experiments are of limited value only.

The Plexuses of the Pelvic Brain.

The pelvic brain practically emits the nerves to the pelvic viscera, but especially the plexuses of the genital tract. The table represents the scheme: 
Plexuses of the Pelvic Brain. - l. Plexus uterinus. 2. Plexus vaginalis. 3. Plexus vesicalis. 4. Plexus rectalis. 
1. Plexus uterinus is emitted to the uterus from the pelvic brain. In infant cadavers I have counted as many as eight different strands of nerves passing from the pelvic brain to the uterus. In the infant cadavers one can observe several nerves passing from the pelvic brain over the external border of the ureter to penetrate finally the myometrium. The first proposition to assert is that the uterus is practically supplied by two plexuses, viz.: (a) the plexus interiliacus (hypogastricus) sends one (two or three) branches directly to the uterus without first entering the pelvic brain; (b) the plexus uterinus, which passes directly from the pelvic brain to the uterus, where it anastomoses with the branches of the plexus interiliacus. Hence the uterus is supplied by branches of the plexus interiliacus directly from the abdominal brain and the plexus uterinus directly from the pelvic brain - leaving the abdominal brain as the chief ruling potentate of the abdominal viscera, while the pelvic brain is a subordinate, local, ruler of the pelvic viscera. The plexus uterinus accompanies the uterine vessels in general only - not in particular like the intimate relation of the plexuses of the abdominal brain to its visceral vessels. The plexus uterinus presents large, strong branches to the cervix uteri, which is unusually rich in nerve supply. The order of richness of nerve supply to the uterus is (a) cervix, luxuriant; (b) corpus, rich; (c) fundus uteri, abundant. The form of the nerve supply to the uterus imitates it, viz.: fan-shaped. In the illustrations of the nerves of the uterus what is presented is the main superficial branches of the plexus interiliacus and plexus uterinus which accompany the major uterine arteries the most intimately along the lateral uterine borders (see figure 3). 
The branches from the plexus interiliacus (one to three) are distributed on the dorsal wall of the cervix, becoming distributed on the dorso-lateral border of the fundus uteri, where they anastomose with the branches of the plexus ovaricus at the junction of the uterus and oviduct, where is located (especially marked in infants) a ganglion. The dorsal surface of the fundus also receives numerous branches from the branches of the plexus interiliacus. Finally the branches directly from the plexus interiliacus (which is directly from the abdominal brain through the plexus aorticus) supply strong, large nerves which are richly distributed to the cervix, corpus, fundus, and oviduct. They anastomose solidly and compactly with the plexus ovaricus and plexus uterinus from the pelvic brain. The plexus uterinus - major nerve supply to the uterus - originates in the pelvic brain. The plexus uterinus, like the plexus interiliacus, approaches the uterus from the neck and lateral border. This leash of ganglionated uterine nerves from the cervico-uterine ganglion in contradistinction to the branches of the plexus interiliacus, supplies the ventro-lateral border of the uterus, and courses more intimately in relation with the uterine segment of the utero-ovarian artery. Many of the large nerves of this plexus are superficial, simulating the superficial position of the artery. As the branches of the plexus interiliacus (direct from the abdominal brain) richly supply the dorsal surface of the corpus and fundus uteri so that the plexus uterinus (directly from the pelvic brain) luxuriantly supplies the ventral surface of the cervix, corpus and fundus uteri. Branches from the vesical ganglia pass to the plexus 
uterinus, thus aiding to make the uterus and bladder act clinically as one organ. The solidly anastomosed plexuses of the uterine nerves continually increasing their area of distribution and their number of multiplying peripheral branches as they proceed toward the fundus, finally sends branches to anastomose with the plexus ovaricus, especially at the oviductal junction, where lies a marked ganglion. This utero-oviductal ganglion appears to be the nerve center from which radiate nerves to the fundus uteri and distal oviduct as well as to the muscular plates lying in the ligamentum latum. The entire uterus is surrounded and traversed by a closely woven network of ganglionated nerve plexuses. The microscopic ganglia are most numerous in the region of the cervix, especially adjacent to the pelvic brain. The uterus is abundantly and luxuriantly supplied by vasomotor sympathetic nerves from which, could we dissolve the substance of the uterus, leaving the network, they would appear like a spider's web. It must be remembered that the uterus is a coalesced organ, and hence the adult nerve supply is a complex affair resembling the adult circulation, which is most extraordinarily demonstrated by corrosion anatomy. 
2. Plexus vaginalis is emitted from the pelvic brain to the vagina. The vaginal plexus is a rich leash or ganglionated plexus of nerves which surround the vagina like a network of cords surrounding a rubber ball. The vaginal nerve plexus and vaginal vein plexus, both rich, complicated and abundant, intertwine and interweave with each other. The rich vaginal plexus is bedecked with numerous ganglia at the points of nerve convergence. The meshes of the vaginal plexus, being occupied by fatty tissue, connective tissue, lymph and blood vessels, its dissection is accompanied with difficulty. Infant cadavers should be chosen to facilitate correct exposure of the finer constituents of the vaginal plexus. As the bladder is supplied by a large branch from the third sacral nerve, so the vagina is supplied from a large branch of the fourth sacral nerve. The ganglionated nerve cords from the pelvic brain surround the vagina like a mighty network, ventrally and dorsally. The vaginal plexus also emits many large nerves to the rectum and bladder. The ventral vaginal nerve leashes course proximalward and distalward. The larger ganglia of the vaginal leash or plexus occur at the proximal ventral vaginal fornix, while on the distal ventral end of the vagina the ganglia are numerous, but more limited in dimensions. The ganglia of the dorsal vaginal wall is limited in number. The entire vagina is completely surrounded by a closely woven ganglionated nerve network. These perivaginal and paravaginal plexuses stand in intimate relation with the pelvic brain. 
Toward the central longitudinal axis of the uterus and vagina the genital plexuses diminish, simulating exactly the genital blood and lymph supply. 
3. Plexus vesicalis is emitted from the pelvic brain to the bladder. The vesical plexus is of the powerful, rich, ganglionated plexuses or leashes of the pelvic brain. It is solidly andcompactly anastomosed to the plexus rectalis, but especially to the plexus uterinus, inducing the rectum, uterus and bladder to act clinically or symptomatically as one apparatus. For description see nerves of tractus urinarius. 
4. Plexus rectalis is emitted from the pelvic brain to the rectum as rich network of nerves bedecked with ganglia limited in number and dimension. The rectal plexus emitted by the pelvic brain is a fine plexiform leash of nerves which passes distalward on the lateral borders of the rectum, intimately blending with the tissues of the rectal wall. The rectum has not only a rich and complicated nerve supply, but it has a mixed nerve supply. The following table presents a general view of a rectal nerve supply:

Rectal Nerve Supply.

1. Plexus hemorrhoidalls superior (from the arteria mesenterica superior). 
2. Plexus interiliacus (from the abdominal brain). 
3. Plexus hemorrhoidalis medius (accompanying the arteria haemorrhoidalis media). 
4. Plexus hemorrhoidalis inferior (from the arteria hemorrhoidalis inferior and plexus pudendalis sacralis - mixed vasomotor and spinal nerves). 
5. Plexus rectalis (from pelvic brain - a powerful, rich nerve plexus solidly anastomosed to the plexus uterinus and vesicalis). 
6. Plexus sacralis spinalis (branches from the second, third and fourth sacral nerves). 
7. Truncus pelvis sympathicus (lateral sacral ganglia). 
The three great haemorrhoidal plexuses arriving at the rectum via the three haemorrhoidal arteries invest it with a network of rich nerve plexuses. A rich leash of nerves passes to the rectum from the plexus interiliacus. Part of the branches of the plexus pass proximalward on the rectum to anastomose with the plexus haemorrhoidalis inferior (from the inferior mesenteric plexus) while part passes distalward on the rectum, penetrating its coats. Some of the branches of the haemorrhoidal plexus supply the bladder and genitals. From this anatomic distribution of the haemorrhoidal plexus - to genitals, rectum and bladder - it is obvious that the genitals, rectum and bladder are solidly and compactly anastomosed. Clinical work demonstrates this balanced union of organs in the pelvis through nerve connection, as rectal or genital operations will induce inability to micturate. The plexus haermorrhoidalis medius (and inferior) corresponds to the plexus pudendalis on the arteria pudenda. For further description of the rectal nerve supply, see tractus intestinalis. The nervous apparatus ventral, lateral and dorsal to the vagina, that supplying the ureter, that coursing through the parametrium and perimetrium, that supplying the bladder, rectum and ureter, are solidly and compactly anastomosed. They form an inseparable nerve plexus bedecked with ganglia of greater and lesser dimensions surrounding the cervico-vaginal junction. The vast plexuses of the pelvic brain, rich in ganglia, extend from the cervico-vaginal junction distalward to the pelvic floor surrounding with a luxuriant closely woven network, uterus and vagina (tractus genitalis), the rectum (distal tractus intestinalis), the bladder and ureter (distal tractus urinarius).

(B) PHYSIOLOGY.

The physiology of the nerves of the tractus genitalis comprises the function of the genital organs, which are in order of origin: 1, ovulation; 2, absorption; 3, secretion; 4, peristalsis (rhythm); 5, menstruation; 6, gestation; 7, sensation. 
First it should be observed that the abdominal brain originates the plexus aorticus, and the plexus aorticus gives origin to two great nerve plexuses, viz., plexus interiliacus and plexus ovaricus. The plexus interiliacus, so far as the genital tract is concerned, divides into two, i.e., one, the larger branch, terminates in the pelvic brain, while the smaller branch terminates directly in the uterus without first passing through the pelvic brain. The plexus ovaricus arises from the plexus aorticus and terminates practically at the ovary; this plexus, however, proceeds to anastomose with the plexus uterinus in the ligamentum latum. Hence, a larger portion of the nerves which supply the genital tract arise in the abdominal brain and pass to it directly through the plexus interiliacus and plexus ovaricus. On the other hand, a massive plexus (the uterine modified by the sacral spinal nerves) passes through the pelvic brain before it arrives at the genital tract. These anatomical facts demonstrate how solidly and compactly the tractus genitalis is anastomosed to the whole abdominal sympathetic. Besides this must be held in view the modifying influence on the genital tract of the sacral (spinal) nerves through their coalesces with the distal end of the plexus interiliacus, i. e., through the pelvic brain.

Peristalsis - Rhythym of the Tractus Genitalis.

Peristalsis, or rhythm, of the genitals, though one of the common functions of all abdominal viscera (under control of the abdominal brain), is particularly specialized in the tractus genitalis - uterus and oviducts - to a degree of popular demonstration. Rhythm of the uterus to the ordinary observer is its chief characteristic phenomenon. The rhythm, or peristalsis, of the uterus under the direct command of the sympathetic nerve, differs not, except in degree, from the rhythm of other viscera under direct command of the sympathetic, such as the enteron, colon, ureter, spleen, liver pancreas. Such organs as the lungs, heart, stomach, and bladder, though dominated by the sympathetic, yet are so powerfully supplied by the cranial nerves (vagi) and the spinal nerves (sacral) that their rhythm is modified. The periodic rhythm and stately peristalsis of the uterus has induced observers of all time to enquire and wonder as to its cause. That irritation of the plexus interiliacus and of the plexus uterinus is followed by the rhythmical movements of the uterus, is the main testimony of a vast majority of investigators. The myometrium, the complicated muscle of the uterus in general, is maintained and completely developed by menstruation and gestation, otherwise it would atrophy. In the uterus are located nerve ganglia, little brains, smaller ganglia - extended or transported from the pelvic brain to the uterus, which I termed fifteen years ago automatic menstrual ganglia. They are local rulers of muscle or myometrial rhythm. When the automatic menstrual ganglia are periodically bathed in extra blood (which is a stimulant or excitant) they explode rhythmically, the uterine muscle or myometrium assumes an active, vermicular movement; thus the myometrium or uterine muscle is preserved from atrophic death. Extra absorption of the uterine glandular apparatus is due to the extra trauma of the muscular bundles on the utricular glands. The myometrium thrashes, massages, and whips the glands to extra secretary labors. Myometrial activity and glandular activity are concomitant - cause and effect. The chain of events is: extra blood to the automatic menstrual ganglia induces extra myometrial rhythm. Extra uterine peristalsis induces extra massage, excitation, to the uterine glands, which results in extra secretion. Therefore, be it observed the dominating nerve of the uterus - the sympathetic functionates as a unit - no conflict, in rhythm which develops the myometrium. During gestation the automatic menstrual ganglia become bathed with continual extra blood. Profound congestion, progressive exalted engorgement, produce extra nourishment and multiply elements until the gestating uterus is perhaps fifty times the dimension of the resting uterus., The gestating uterus is always in motion - rhythm. One curious feature I have noted in the arteries of gestating uteri of animals and man, and that is, that the uterine artery was enlarged, hypertrophied, exactly from its origin in the internal iliac. No part of the iliac was enlarged. Hence gestation belongs entirely to the tractus genitalis, to the utero-ovarian arterv. The function is distinct, does not glide into any other visceral tract. The sympathetic nerve has through aeons of ages become, differentiated to perform separately and distinctly the important functions of the tractus genitalis. The sympathetic nerve, nervus vasomotorius, originally belonged to the arterial system. It is differentiated at present to control some veins and also the gradually added tractus lymphaticus. Great importance lies in the tractus vascularis and its ruler, nervus vasomotorius. The future problems, especially as regards shock, must be solved in the wide field of the sympathetic nerve and circulatory system. 
Besides rhythm or peristalsis the nerves of the uterus preside over the functions of absorption, secretion, menstruation, gestation, and sensation of the uterus, a description of the physiology of which space forbids. The physiology of the oviduct is under the control of the sympathetic nerve and we may note the following points in its functional activity: 
The object of the oviduct is transportation - export and import service - of spermatozoa proximalward and of ova distalward, forcing the impregnated ovum distalward to the uterine cavity. The following are the main physiologic factors in oviductal transportation: 
1. The periodic congestion of the genitals, stimulation of the automatic menstrual ganglia by extra blood. 
2. The cilia of the oviductal mucosa whip continually toward the uterus distalward, not only forcing the ova distalward, but also creating a fluid current. 
3. The congestion induces the endosalpinx to secrete a fluid which makes the oviduct a canal to float the ovum distalward: 
4. Congestion induces continual oviductal peristalsis, which forces the ova distalward. 
5. The contraction of the muscular processes in the ligamentum latum enhances the peristalsis. 
6. The shortening of the fimbria ovarica which induces the infundibulum to apply its mucous surface to the ovary, capturing the ovum. 
7. The congestion induces the secretion of mucus and glues the infundibulum on the surface of the ovary. 
8. Intra-abdominal pressure aids the distal progress of the ova. 
9. The enlarging of the ovum approaching the infundibulum aids. 
10. Secretion of the endosalpinx produces a fluid medium adjacent to the proximal oviductal end and the cilia of the fimbriae induce a current toward the abdominal ostium. 
11. The oviduct has an import (spermatozoa) and an export (ova) service. It is analogous to the vas deferens in the male. The spermatozoa pass through the oviduct proximalward, while the ova pass through it distalward. 
12. The oviduct is a temporary (or pathologic permanent) depot for conception. The oviduct (ampulla) is a physiologic sporting ground for ova and spermatozoa. It has three general physiologic offices to fulfill, viz.: (a) to secure and transport the ovum (distalward) to the cavity of the uterus; (b) to conduct spermatozoa proximalward; (c) to serve as physiologic temporary (or pathologic permanent) depot of conception. All the physiologic statements in regard to the ovary will be, that the rich plexus ovaricus rules ovulation, but also, perhaps, some form of internal ovarian secretion is necessary for the best normal corporeal existence. The physiology of the tractus genitalis is vigorous, as it is supplied by a luxuriant system of sympathetic nerves. With the higher forms of differentiated animals the magnitude and influence of the genitalis increases. The higher the animal the more thought is applied to the genitals, the more periodic congestion and permanent increase of nerve and blood supply.

The intense attention paid to sex in higher animals, such as monkey and man, is a remarkable phenomenon, and attention induces blood flow, congestion.

At the bottom of the sex lie ambition, hope, and much of the pride of life. Man's life and thoughts are arranged around sex as a center. Hence the genital nerve and blood supply and consequent genital physiology will remain an increasing maximum.

For the detailed physiology noted in the subjects "Abdominal Brain" and "Pelvic Brain" the reader is referred to the Medical Age for July, 1905, and the Medical Review of Reviews for November, 190