Adrenergic and Cholinergic Innervation of the Rat Urinary Bladder

The autonomic innervation of the rat urinary bladder was studied using histochemical methods and nerve stimulations. A sparse adrenergic innervation of the detrusor muscle was found. It was supposed to originate from long adrenergic neurones. The trigonum area had a rich supply of adrenergic fibres, probably derived from short adrenergic neurones. A uniformly rich supply of acetylcholine-esterase (AChE)-positive nerves was found in the whole bladder. Postganglionic sympathetic denervation caused no detectable change of adrenergic or AChE-positive nerves in the bladder, while parasympathetic decentralization or denervation produced a total disappearance of adrenergic fibres. The AChE-positive nerves were appreciably reduced in number after parasympathetic decentralization and not detectable after postganglionic denervation. Neither adrenergic nor AChE-positive ganglion cells could be demonstrated in the bladder wall. Electrical stimulation of the hypogastric nerves or the pelvic nerves distal to the pelvic ganglia elicited contraction of the detrusor muscle. The responses were not affected by hexamethonium, dihydroergotamine or propranolol but were slightly reduced by guanethidine, reduced to about 40% by atropine and potentiated by eserine. Stimulation of the pelvic nerve proximal to the pelvic ganglion was partially blocked by hexamethonium. It is concluded that the urinary bladder of the rat is supplied by postganglionic adrenergic fibres mainly via the pelvic nerves and only to a lesser extent via the hypogastric nerves. Probably cholinergic fibres pass to the bladder mainly via the pelvic nerves but also via the hypogastric nerves, having their cellbodies outside the bladder wall, partly proximal to the pelvic ganglia.     

Adrenergic and cholinergic innervation of the rag urinary bladder.

The autonimic innervation of the rat urinary bladder was studied using histochemical methods and nerve stimulations. A sparse adrenergic innervation of the detrusor muscle was found. It was supposed to originate from long adrenergic neurones. The trigonum area had a rich ssupply of adrenergic fibres, probably derived from short adrenergic neurones. A uniformly rich supply of acetylcholine-esterase (AChE)-positive nerves was found in the WHOLE BLADDER. Postganglionic sympathetic denervation caused no detectable change of adrenergic or AChE-positive nerves in the bladder, while parasympathetic decentralization or denervation produced a total disappearance of adrenergic fibres. The AChE-positive nerves were appreciably reduced in number after parasympathetic decentralization and not detectable after postganglionic denervation. Neither adrenergic nor AChE-positive ganglion cells could be demonstrated in the bladder wall. Electrical stimulation of the hypogastric nerves or the pelvic nerves distal to the pelvic ganglia elictied contraction of the detrusor muscle. The responses were not affected by hexamethonium, dihydroergotamine or proparanolol but were slightly reduced by guanethidine, reduced to about 40% by atropine and potentiated by eserine. Stimulation of the pelvic nerve proximal to the pelvic ganglion was partially blocked by hexamethonium. It si concluded that the urinary bladder of the rat is supplied by postganglionic adrenergic fibres mainly via the pelvic nerves and only to a lesser extent via the hypogastric nerves. Probably cholinergic fibres pass to the bladder mainly via the pelvic nerves but also via the hypogastric nerves, having their cellbodies outside the bladder wall, partly proximal to the pelvic ganglia.     

Topography of the pelvic autonomic nervous system and its potential impact on surgical intervention in the pelvis

Bladder, bowel, and sexual dysfunction caused by iatrogenic lesions of the inferior hypogastric plexus (IHP) are well known and commonly tolerated in pelvic surgery. Because the pelvic autonomic nerves are difficult to define and dissect in surgery, and their importance often ignored, we conducted a gross anatomic study of 90 adult and four fetal hemipelves. Using various non-surgical approaches, the anatomic relations and pathways of the IHP were dissected. The IHP extended from the sacrum to the genital organs at the level of the lower sacral vertebrae. It originated from three different sources: the hypogastric nerve, the sacral splanchnic nerves from the sacral sympathetic trunk (mostly the S2 ganglion), and the pelvic splanchnic nerves, which branched primarily from the third and fourth sacral ventral rami. These fibers converge to form a uniform nerve plate medial to the vascular layer and deep to the peritoneum. The posterior portion of the IHP supplied the rectum and the anterior portion of the urogenital organs; nerve fibers traveled directly from the IHP to the anterolateral wall of the rectum and to the inferolateral and posterolateral aspects of the urogenital organs. The autonomic supply from the IHP was supplemented by nerves accompanying the ureter and the arteries. An understanding of the location of the autonomic pelvic network, including important landmarks, should help prevent iatrogenic injury through the adoption of surgical techniques that reduce or prevent postoperative autonomic dysfunction.     

Nervous regulation of the tone of the retractor penis muscle in the goat

The nervous control of the retractor penis muscle (rp) was investigated in the anaesthetized goat. Also, isolated field stimulated strips of the muscle were studied. The noradrenaline (NA) and acetylcholine (ACh) content of the rp was determined, and histochemistry for adrenergic and acetylcholinesterase (AChE) positive nerves was performed. The muscle exhibited spontaneous activity that persisted after section of all nerves. There was, however, also a tendency of the activity to follow the general vasomotor tone, which disappeared after section of the sympathetic chains. The excitatory adrenergic nerves which innervate the muscle come from the sympathetic chains and run along the pudendal, the hypogastric and the pelvic nerves. The rp has a dense network of adrenergic fibres and is very sensitive to excitatory adrenergic stimulation. It has a fairly large NA content, which is higher in old goats (5.95 ± 0.42 μg g^-1) than in young goats (2.87 ± 0.78 μg g-¹). Inhibitory non-adrenergic non-cholinergic (NANC) innervation reaches it via the pelvic and the hypogastric nerves. The maximum inhibitory response is reached at low frequencies (2–4 Hz). Cholinergic prejunctional inhibition of the excitatory response to sympathetic chain stimulation was effected by simultaneous stimulation of the hypogastric nerves. In vitro experiments confirmed the presence of endogenous cholinergic muscarinic suppression of the excitatory adrenergic neurotransmission. Significant amounts of ACh (0.81 7 plusmn; 0.18 μg g^-1) are present in the muscle, and it contains strongly AChE positive nerve fibres and nerve cell bodies. It is concluded that the goat rp is innervated by sympathetic adrenergic excitatory nerves and parasympathetic NANC inhibitory nerves. It further has a direct sympathetic inhibitory NANC innervation, and an indirect inhibitory cholinergic innervation which at least in part is sympathetic.     

Identification of the origin of adrenergic and cholinergic nerve fibers within the superior hypogastric plexus of the human fetus

Nerve fibers contributing to the superior hypogastric plexus (SHP) and the hypogastric nerves (HN) are currently considered to comprise an adrenergic part of the autonomic nervous system located between vertebrae (T1 and L2), with cholinergic aspects originating from the second to fourth sacral spinal segments (S2, S3 and S4). The aim of this study was to identify the origin and the nature of the nerve fibers within the SHP and the HN, especially the cholinergic fibers, using computer-assisted anatomic dissection (CAAD). Serial histological sections were performed at the level of the lumbar spine and pelvis in five human fetuses between 14 and 30 weeks of gestation. Sections were treated with histological staining [hematoxylin-eosin (HE) and Masson''s trichrome (TriM)] and with immunohistochemical methods to detect nerve fibers (anti-S100), adrenergic fibers (anti-TH), cholinergic fibers (anti-VAChT) and nitrergic fibers (anti-nNOS). The sections were then digitalized using a high-resolution scanner and the 3D images were reconstructed using winsurf software. These experiments revealed the coexistence of adrenergic and cholinergic fibers within the SHP and the HNs. One-third of these cholinergic fibers were nitrergic fibers [anti-VACHT (+)/anti-NOS (+)] and potentially pro-erectile, while the others were non-nitrergic [anti-VACHT (+)/anti-NOS (−)]. We found these cholinergic fibers arose from the lumbar nerve roots. This study described the nature of the SHP nerve fibers which gives a better understanding of the urinary and sexual dysfunctions after surgical injuries.     

Principal mechanisms controlling penile retraction and protrusion in rabbits

The effects on penile volume of nerve stimulations and drugs injected into the systemic circulation were studied plethysmographically. Dilator responses at selective perfusion of the penile artery were studied by measuring the perfusion pressure. The main results and conclusions are: The penis has an adrenergic vasoconstrictor supply coming from the sacrococcygeal parts of the sympathetic chains. A very low (0.2 Hz) vasomotor tone keeps the penis relaxed. If this tone is interrupted the penis will protrude but autoregulation will soon take over and eventually produce hyperinvolution of the penis. Two vasodilator paths, both with pelvic ganglionic relays, were found. 1) The pelvic parasympathetic nerves, probably having mainly non-cholinergic postganglionic neurons and operating quite effectively at low frequencies. 2) The sympathetic hypogastric nerves, presumably having at least partly cholinergic postganglionic neurons which, apart from muscarinic dilation of minute inflow resistance vessels to the erectile tissue, may also work by suppression of excitatory adrenergic neurotransmission. The pelvic and hypogastric vasodilator outflows work synergistically. The vasoconstrictor nerves are very strong and efficient antagonists of the vasodilator nerves.     

Stimulation of adrenergic nerve fibres to the urinary bladder of the rat.

The contraction of the rat detrusor muscle caused by electrical stimulation of the hypogastric or pelvic nerves was followed by relaxation when the nerves were stimulated for a short period. The relaxation was more pronounced when the initial contraction was reduced by atropine. It was found to be mediated by adrenergic fibres acting on inhibitory beta2-receptors. Stimulation of the hypogastric or pelvic nerves at high frequencies increased the contractile response probably via adrenergic fibres activating excitatory alpha-receptors.     

Stimulation of Adrenergic Nerve Fibres to the Urinary Bladder of the Rat

The contraction of the rat detrusor muscle caused by electrical stimulation of the hypogastric or pelvic nerves was followed by relaxation when the nerves were stimulated for a short period. The relaxation was more pronounced when the initial contraction was reduced by atropine. It was found to be mediated by adrenergic fibres acting on inhibitory β²-receptors. Stimulation of the hypogastric or pelvic nerves at high frequencies increased the contractile response probably via adrenergic fibres activating excitatory α-receptors.     

Effects of chronic deafferentation on adrenergic ganglion cells and small intensely fluorescent cells

Summary To determine the reaction of adrenergic ganglion cells and small intensely fluorescent (SIF) cells to chronic deafferentation, catecholamine fluorescence of the major pelvic ganglion (MPG) of the rat has been studied following section of the hypogastric nerve, pelvic nerve and sympathetic trunk. Only minor changes occurred following section of the hypogastric nerve; the fluorescence surrounding a few adrenergic ganglion cells became brighter. In contrast, pelvic neurectomy resulted in the appearance of numerous varicose fibres and an increase in the fluorescent intensity of fibres enclosing many ganglion cells. Varicose fibres seem to originate from adrenergic ganglion cells and SIF cells. In many instances, nests of SIF cells gave rise to radially oriented fibres. Removal of the sympathetic trunk appeared to have no effect on the MPG. It is suggested that the appearance of varicose fibres from SIF cells following deafferentation may be due to collateral sprouting of these cells or to the increased fluorescence of pre-existing processes.     

Peptide containing nerves in the ureter of the guinea-pig and cat

We report the presence of two regulatory peptides, substance P and vasoactive intestinal polypeptide (VIP), in the ureter and their localisation by both light- and electron-microscopy to autonomic nerves. VIP- and substance P-like immunoreactive nerves showed, in general, a similar anatomical distribution in the various layers of the ureter. Immunoreactive nerves were observed running along the smooth muscle coat, parallel to muscle bundles, around blood vessels and in the submucosa, particularly beneath the epithelium. In addition, scattered VIP-like immunoreactive ganglion cells and nerve fibres were seen in adventitial ganglia around the most distal part of the ureter and ureter-bladder junction in the cat. The guinea-pig ureter contained principally substance P-like immunoreactivity, whereas the cat ureter possessed mainly VIP-like material.The distribution of adrenergic and cholinergic nerves was compared with those containing peptides. Peptide-containing nerves had a more extensive distribution than adrenergic ones, which were mainly associated with blood vessels; however, cholinergic nerves were often localised in the same areas as those possessing peptides. Conventional electron microscopy revealed that separate p-type (peptidergic) and cholinergic nerve terminals were frequently present in the same nerve bundles, although in the cat ureter some 50% of the p-type profiles contained a mixed population of vesicles, characteristic of both cholinergic and p-type nerves. VIP- and substance P-like immunoreactivity were also localised at the ultrastructural level by means of a gold-labelled goat-antirabbit serum.     

全直肠系膜切除相关盆自主神经的解剖学观察

目的：阐述全直肠系膜切除术相关盆自主神经的局部解剖学特点，探讨盆自主神经保留的部位和对策。方法：对20具男性盆腔固定标本进行解剖观察。结果：腹主动脉丛远离肠系膜下动脉起点；上腹下丛贴近骶岬表面；腹下神经部分毗邻输尿管；盆内脏神经伴行直肠中动脉外侧部；下腹下丛位于直肠系膜后外侧；其直肠侧支走行于直肠侧韧带内，直肠前支向前穿过Denonvilliers筋膜后叶；勃起神经位于Denonvilliers筋膜前叶外侧部。结论：盆自主神经保留的部位是：离断肠系膜下血管时的腹主动脉丛左干，直肠后分离时的上腹下丛和腹下神经，直肠侧面分离时的下腹下丛和盆内脏神经，直肠前分离时的勃起神经。共同原则是：在直肠后间隙中贴近直肠系膜操作；直视下操作；避免过度牵引直肠系膜。     

Transmitter profile and spinal inputs of pelvic ganglion cells projecting with preganglionic axons along the hypogastric and pelvic nerves of the male rat

Pelvic autonomic ganglion cells receive spinal preganglionic inputs via the hypogastric (lumbar) or pelvic (sacral) nerves. Damage to these nerves stimulates axogenesis (sprouting) from pelvic ganglion cells and two possible triggers are deafferentation (decentralisation) or, if some ganglion cells project centrally in these nerves, axotomy. We have used a combination of retrograde tracing and immunohistochemistry in male rats to identify the number of pelvic ganglion cells that project centrally along these nerves, their transmitter type and the spinal level of their preganglionic inputs. Only a small number (<1%) of pelvic ganglion cells project along these nerves; 29-65 project in each hypogastric nerve and 41-71 in each pelvic nerve. These neurons comprise of both cholinergic and noradrenergic classes and the majority receive preganglionic inputs from the nerve in which they also project. These results suggest that damage of the hypogastric and pelvic nerves close to the pelvic ganglion is unlikely to cause axotomy of many pelvic ganglion cells. Therefore deafferentation rather than axotomy is likely to be the primary trigger of axogenesis occurring in pelvic ganglia after these lesions.     

The innervation of the vas deferens of the guinea-pig

1. The compound action potential of the hypogastric nerve of the guinea-pig contained two main elevations. The low-threshold fibres had a range of conduction velocities from 1.5 to 10 m/sec. The high threshold fibres conducted action potentials at less than 1 m/sec. The hypogastric nerve contained small myelinated fibres and non-myelinated fibres.2. In the preparation in vitro, junctional potentials and contractions were elicited by stimulation of the rapidly conducting fibres alone. Trains of C fibre volleys were ineffective.3. In the preparation in vivo, conduction from the hypogastric nerve to the vas deferens nerve was unidirectional and abolished by hexamethonium. After the administration of hexamethonium, the contraction produced by stimulation of the vas deferens nerve was unaffected.4. The close arterial injection of acetylcholine (ACh) into the pelvic viscera caused centrifugal activity in the motor fibres of the vas deferens nerve, but no impulses were detected in the hypogastric nerve.5. Ganglion cells are present in the last 2 cm of the hypogastric nerve.6. It is concluded that there is a ganglionic relay between the hypogastric and vas deferens nerves.     

Systematization of the vesical and uterovaginal efferences of the female inferior hypogastric plexus (pelvic): applications to pelvic surgery on women patients

Objective To locate and describe the various efferences of the plexus in order to make it easier to avoid nerve lesions during pelvic surgery on women patients through a better anatomical knowledge of the inferior hypogastric plexus (IHP). Materials and methods We dissected 27 formalin embalmed female anatomical subjects, none of which bore any stigmata of subumbilical surgery. The dissection was always performed using the same technique: identification of the inferior hypogastric plexus, whose posterior superior angle follows on from the hypogastric nerve and whose top, which is anterior and inferior, is located exactly at the ureter’s point of entry into the base of the parametrium, underneath the posterior layer of the broad ligament. Results The IHP is located at the level of the posterior floor of the pelvis, opposite to the sacral concavity. Its top, which is anterior inferior, is at the point of contact with the ureter at its entry into the posterior layer of the broad ligament. The uterovaginal, vesical and rectal efferences originate in the paracervix. Three efferent nerves branch, two of them from its top and the third from its inferior edge: (1) A vaginal nerve, medial to the ureter, follows the uterine artery and divides into two groups: anterior thin, heading for the vagina and the uterus; posterior, voluminous, heading in a superior rectal direction (=superior rectal nerve). (2) A vesical nerve, lateral to the ureter, divides into two groups, lateral and medial. (3) The inferior rectal nerve emerges from the inferior edge of the IHP, between the fourth sacral root and the ureter’s point of entry into the base of the parametrium. Conclusion The ureter is the crucial point of reference for the IHP and its efferences and acts as a real guide for identifying the anterior inferior angle or top of the IHP, the origin of the vaginal nerve, the level of the ureterovesical junction and the division of the vesical nerve into its two medial and lateral branches. Dissecting underneath and inside the ureter and the uterine artery involves a risk of lesion of the vaginal nerve and its uterovaginal branches. Further forward, between the intersection and the ureterovesical junction, dissecting and/or coagulating under the ureter involves a risk of lesions to the vesical nerve, which are likely to explain the phenomena of denervation of the anterior floor encountered after certain hysterectomies and/or surgical treatments of vesicoureteral reflux.     

The inferior hypogastric plexus (pelvic plexus): its importance in neural preservation techniques

The progress in the surgery of male neurological cancers relies on the anatomico-surgical approach to the pelvic neural structures. The objective of our study was to provide a better understanding of the inferior hypogastric plexus (IHP) and its anatomical relationships in order to spare it during radical prostatectomy. Fifteen male formalin-preserved cadavers which had no sub-umbilical scar were used. In five subjects, the superior hypogastric plexus (SHP) and the pre-sacral plexus were displayed then the IHP and its sacral afferents (pelvic splanchnic nerves or erector nerves of Eckhardt) were dissected out. Serial sections of the IHP were then studied in ten subjects. This allowed its identification on certain imaging sections obtained in pelvic tumor pathology and these made up the "reference cuts". The IHP lies within a fibro-fatty plate which is flat, rectangular, sub-peritoneal, sagittal and symmetrical. It arises at the level of the intersection between the vas deferens and the terminal pelvic ureter and follows the postero-lateral aspect and circumvolutions of the seminal vesicle, with which there is a plane of surgical cleavage. The seminal vesicle is, therefore, an essential landmark for this neural structure. The plane of this cleavage may be used in pelvic cancer surgery. The safest technical means of respecting sexual function and the integrity of the IHP is to keep it at a distance. The preservation of a lateral layer of the seminal vesicle is probably a method of limiting these complications as long as this does not conflict with the oncological clearance. An irregular communicating branch was found in one of five cases between the IHP, the sacral plexus and the pudendal nerve. This communicating branch lay immediately behind the intersection between the vas deferens and the ureter in the sacral concavity. It overhangs the IHP in the seminal vesicle. Impotence remains a frequent complication after radical prostatectomy. The methods of neural preservation at the prostatic apex are known but neural preservation should also be carried out posteriorly at the lateral pole of the seminal vesicle. The possibility of posterior neural preservation may be assessed pre-operatively by study of the "reference sections". The cleavage plane between the seminal vesicle and the IHP may be used intra-operatively to spare the IHP. The cavernous nerve in particular emerges at the antero-inferior border of the IHP before running along the postero-lateral aspect of the prostate. It therefore passes in contact with the seminal vesicle and may as a result be injured during radical prostatectomy with vesiculectomy. A proximal communicating branch between the IHP and the pudendal nerve is irregular. Such communicating branches may explain a better recovery of sexual function in curative neurological cancer surgery. The essential relationship of the IHP is with the seminal vesicle. The two are in tight contact and the seminal vesicle has a true plane of surgical cleavage with IHP. The risk of injuries to the posterior erectile mechanisms can be reduced either by using the cleavage plane between the IHP and seminal vesicle or by leaving a layer of the seminal vesicle when the oncological conditions allow. During celio-surgery, the operator must be careful to retract the little bands of the seminal vesicle and divide the fibrous and vascular tracts which tighten during this maneuver. During an abdominal approach, dissection of the seminal vesicle takes place at the bottom of a real pit. The operator must carry out the division leaving a layer of the seminal vesicle in place rather than trying to extract all the seminal vesicle by placing the forceps blindly. This maneuver is naturally dependent on the oncological situation. The anatomical confirmation of a regular or irregular proximal or distal communicating branch between the IHP and the pudendal nerve is probably an explanation for the sometimes uncertain results of new techniques of neural preservation in curative cancer surgery.     

Innervation of the abdominopelvic ureter in the cat

The distribution of cholinergic and adrenergic nerves in the cat ureter was studied by specific histochemical techniques for acetylcholinesterase and norepinephrine. The innervation of the ureter is characterized by (1) a generalized dual cholinergic and adrenergic nerve supply, (2) the presence of muscular innervation, (3) a continuity of terminal muscular and vascular nerves, (4) a widespread distribution of ganglion cells except in the pelviureteric area and (5) regional variations in the density of both cholinergic and adrenergic elements. On the basis of these findings, it is suggested that in the cat ureter peristalsis has a myogenic origin in the proximal end of the ureter, but its distalward propagation along the abdominal and pelvic segments is controlled by a dual sympathetic and parasympathetic influence which is mediated in part through a system of intrinsic ureteric ganglion cells.     

Observations on the anatomy and amine histochemistry of the nerves and ganglia which supply the pelvic viscera and on the associated chromaffin tissue in the guinea-pig

Summary The organs of the lower abdominal and pelvic regions of the guinea-pig receive nerves from the inferior mesenteric ganglia and pelvic plexuses. The inferior mesenteric ganglia connect with the sympathetic chains, the superior mesenteric ganglia, the pelvic plexuses via the hypogastric nerves, and with the gut. Each pelvic plexus consists of anterior and posterior parts which send filaments to the internal generative organs and to the rectum, internal anal sphincter and other pelvic organs. The pelvic nerves enter the posterior plexuses, which also receive rami from the sacral sympathetic chains. The adrenergic neurons of the pelvic plexuses are monopolar, do not have dendrites and are supplied by few varicose adrenergic axons. Nearly all the nerves contain adrenergic fibres. After exposure to formaldehyde vapour the chromaffin cells appear brightly fluorescent with one or two long, often varicose, processes. Most of the chromaffin cells are in Zuckerkandl's organ or in chromaffin bodies associated with the inferior mesenteric ganglia. Groups of chromaffin cells are found along the hypogastric nerves and in the pelvic plexuses; they become smaller and fewer as regions more posterior to Zuckerkandl's organ are approached.This work was supported by grants from the Australian Research Grants Committee and the National Health and Medical Research Council. We thank Professor G. Burnstock for his generous support.     

Choline Acetyltransferase Activity in the Denervated Urinary Bladder of the Rat

After extirpation of the pelvic ganglia the choline acetyltransferase activity decreased markedly indicating that most of the postganglionic cholinergic neurones of the bladder take this route. A small decrease in the activity of this enzyme was found after section of the hypogastric nerves, showing that these nerves contribute to some extent to the cholinergic innervation. The residual enzyme activity found after a combination of the two surgical procedures suggests that neurones relay distal to the level of the section of the hypogastric nerves and pass outside the pelvic ganglia and (or) that neurones pass the pelvic ganglia and relay distal to them. Electrical stimulation of the hypogastric nerves after extirpation of the pelvic ganglia and the use of blocking drugs showed on the existence of cholinergic neurones passing outside the pelvic ganglia, some of them relaying distal to the point of stimulation.     

The female inferior hypogastric (= pelvic) plexus: anatomical and radiological description of the plexus and its afferences—applications to pelvic surgery

AIM OF THE STUDY: We wanted to determine the anatomical features of the inferior hypogastric plexus (IHP), and the useful landmarks for a safe surgical approach during pelvic surgery. MATERIALS AND METHODS: We dissected the IHP in 22 formolized female anatomical subjects, none of which bore any stigmata of subumbilical surgery. RESULTS: The inferior hypogastric plexus (IHP) is a triangle with a posterior base and an anterior inferior top. It can be described as having three edges and three angles; its inferior edge stretches constantly from the fourth sacral root to the ureter's point of entry into the posterior layer of the broad ligament; its cranial edge is strictly parallel to the posterior edge of the hypogastric artery, along which it runs at a distance of 10 mm; its posterior (dorsal) edge is at the point of contact with the sacral roots, from which it receives its afferences. They most frequently originate from S3 or S4 (60%) and then, in one or two branches, often from S2 (40%), never from S1 and in exceptional cases from S5 (20%). There are sympathetic afferences in 30% of cases, usually through a single branch of the second, third or fourth sacral ganglion. All IHPs have at least one sacral afference and sometimes there may be up to three afferences from the same sacral root. Its dorsal cranial angle, which is superior, comes after the SHP (hypogastric nerve or presacral nerve filament); its anterior inferior angle is located exactly at the ureter's point of entry into the posterior layer of the broad ligament. This is the top of the IHP; its posterior inferior angle is located at the point of contact with the fourth sacral root. At its entrance at the base of the parametrium the pelvic ureter is the anterior, fundamental positional reference for the IHP. The vaginal efferences come out of the top of the IHP through branches leading to the bladder, the vagina and the rectum, which originate through two trunks exactly underneath the crossing point of the ureter and the uterine artery: (i) one trunk leading to the bladder runs along and underneath the ureter and divides into two groups, which are lateral and medial, trigonal. (ii) the trunk leading to the vagina runs along the inferior edge of the uterine artery. At the point of contact with the lateral edge of the vagina, it splits into two groups: anterior thin and posterior voluminous. Some of its branches perforate the posterior wall of the vagina and are distributed to the rectovaginal septum in a tooth comb pattern. The inferior branches, which emerge from the inferior edge of the IHP, reach the rectum directly. The dissection of the 22 specimens allowed us to describe three efferent plexuses: a vaginal rectal plexus, a vesical plexus and a inferior rectal plexus. So the IHP's anterior, fundamental positional reference is the pelvic ureter at the point where it enters at the base of the parametrium, then at the crossing point of the uterine artery. The ureter is the vector for vesical efferences, the uterine artery is the vector for vaginal efferences, which are thus sent into the vesicovaginal septum and the rectovaginal septum. This surgical point of reference is of vital importance in nerve sparing during the course of a simple or extended hysterectomy. Any dissection carried out underneath and outside of the ureter inevitably carries a risk of lesions to its efferent, lateral vesical or medial, rectovaginal fibres.