1.
Lymphatic vessels and nodes of abdomen and pelvis
2. Lumbar part of sympathetic trunk and
abdominal division of vagus. Autonomic plexus of abdomen
3. Pelvic part of sympathetic trunk. Pelvic division
of the parasympathetic nervous system. Autonomic plexus of pelvis
Theme 1. Lymphatic vessels and
nodes of abdomen and pelvis
In abdominal cavity, as and in pelvis, lymphatic nodes may be divided
into two sets, parietal and visceral.
The Visceral lymphatic nodes
dispose along the course of big vessels come away from abdominal aorta, they
receive lymph from all internal abdominal organs: coeliac nodes, right/left
gastric nodes, lymphatic unnulus of cardia, right/left gastroepiploic nodes,
pyloric nodes, pancreatic nodes, splenic nodes, pancreatoduodenal nodes,
hepatic nodes, superior mesenteric nodes and inferior mesenteric nodes.
The lymphatic vessels of the small intestine receive the special designation of
lacteals or chyliferous vessels; they differ in no respect from
the lymphatic vessels generally excepting that during the process of digestion
they contain a milk-white fluid, the chyle. The lymphatic vessels and
nodes of the small intestine positioned in mesentery and empty into intestinal
trunk. The vessels take away lymph from these nodes, pass to lumbar nodes. Efferent vessels of
last form the lumbar trunks, which flowing together form a thoracic duct.
The
parietal Lymph nodes of the pelvis.
The
parietal lymphatic nodes
disposed around aortae and inferior vene cava
- right/left and intermidiate lumbar nodes, lateral
aortic nodes, preaortic nodes, retroaortic nodes, lateral
caval nodes, precaval nodes, retrocaval nodes, inferior
phrenic nodes and inferior epigastric nodes.
Lymphatic vessels of superior half of
abdominal wall pass upward to the axillar
lymphatic nodes. The vessels of inferior half of abdominal wall pass downward
to inguinal lymphatic
nodes.
The Lymph nodes of the Abdomen and Pelvis—The
Lymph nodes of the abdomen and pelvis may be divided, from their situations,
into (a) parietal, lying behind
the peritoneum and in close association with the larger bloodvessels; and (b)
visceral, which are found in
relation to the visceral arteries.
The parietal
nodes include the following groups:
External
Iliac. |
|
Iliac
Circumflex. |
|
Lumbar
|
Lateral
Aortic. |
Common Iliac. |
|
Hypogastric. |
|
Preaortic. |
|
Epigastric. |
|
Sacral. |
|
Retroaortic. |
The External Iliac
Nodes, from eight to ten in number, lie along the external iliac
vessels. They are arranged in three groups, one on the lateral, another on the medial,
and a third on the anterior aspect of the vessels; the third group is, however,
sometimes absent. Their principal afferents are derived from the inguinal and
subinguinal glands, the deep lymphatics of the abdominal wall below the
umbilicus and of the adductor region of the thigh, and the lymphatics from the
glans penis vel clitoridis, the membranous urethra, the prostate, the fundus of
the bladder, the cervix uteri, and upper part of the vagina.
The Common Iliac
Glands, four to six in number, are grouped behind and on the sides of
the common iliac artery, one or two being placed below the bifurcation of the
aorta, in front of the fifth lumbar vertebra. They drain chiefly the
hypogastric and external iliac glands, and their efferents pass to the lateral
aortic glands.
The Epigastric nodes
(lymphoglandulæ epigastricæ), three or four in number, are
placed alongside the lower portion of the inferior epigastric vessels.
The Iliac Circumflex
nodes, two to four in number, are situated along the course of
the deep iliac circumflex vessels; they are sometimes absent.
The Hypogastric
nodes (lymphoglandulæ hypogastricæ; internal iliac gland) surround the hypogastric vessels, and receive
the lymphatics corresponding to the distribution of the branches of the
hypogastric artery, i. e., they receive lymphatics from all the pelvic
viscera, from the deeper parts of the perineum, including the membranous and
cavernous portions of the urethra, and from the buttock and back of the thigh.
An obturator gland is sometimes
seen in the upper part of the obturator foramen.
The Sacral nodes
are placed in the concavity of the sacrum, in relation to the middle and
lateral sacral arteries; they receive lymphatics from the rectum and posterior
wall of the pelvis.
The efferents of the hypogastric group end in the common
iliac glands.
The Lumbar nodes
(lymphoglandulæ lumbales) are very numerous, and consist of right
and left lateral aortic, preaortic, and retroaortic groups.
Iliopelvic glands (lateral view).
The right lateral
aortic nodes are situated partly in front of the inferior vena cava,
near the termination of the renal vein, and partly behind it on the origin of
the Psoas major, and on the right crus of the diaphragm. The left lateral aortic glands form a
chain on the left side of the abdominal aorta in front of the origin of the
Psoas major and left crus of the diaphragm. The glands on either side receive (a)
the efferents of the common iliac glands, (b) the lymphatics from the
testis in the male and from the ovary, uterine tube, and body of the uterus in
the female; (c) the lymphatics from the kidney and suprarenal gland; and
(d) the lymphatics draining the lateral abdominal muscles and accompanying
the lumbar veins. Most of the efferent vessels of the lateral aortic glands
converge to form the right and left
lumbar trunks which join the cisterna chyli, but some enter the pre- and
retroaortic glands, and others pierce the crura of the diaphragm to join the
lower end of the thoracic duct. The preaortic
glands lie in front of the aorta, and may be divided into celiac, superior mesenteric, and inferior mesenteric groups, arranged
around the origins of the corresponding arteries. They receive a few vessels
from the lateral aortic glands, but their principal afferents are derived from
the viscera supplied by the three arteries with which they are associated. Some
of their efferents pass to the retroaortic glands, but the majority unite to
form the intestinal trunk,
which enters the cisterna chyli. The retroaortic
glands are placed below the cisterna chyli, on the bodies of the third
and fourth lumbar vertebræ. They receive lymphatic trunks from the
lateral and preaortic glands, while their efferents end in the cisterna chyli.
the Lymphatic Vessels of the Abdomen and
Pelvis
The lymphatic vessels of the walls of the abdomen and pelvis
may be divided into two sets, superficial and deep.
The superficial vessels
follow the course of the superficial bloodvessels and converge to the
superficial inguinal glands; those derived from the integument of the front of
the abdomen below the umbilicus follow the course of the superficial epigastric
vessels, and those from the sides of the lumbar part of the abdominal wall pass
along the crest of the ilium, with the superficial iliac circumflex vessels.
The superficial lymphatic vessels of the gluteal region turn horizontally
around the buttock, and join the superficial inguinal and subinguinal glands.
The deep vessels
run alongside the principal bloodvessels. Those of the parietes of the pelvis,
which accompany the superior and inferior gluteal, and obturator vessels,
follow the course of the hypogastric artery, and ultimately join the lateral
aortic glands.
Lymphatic Vessels of the
Perineum and External Genitals.—The lymphatic vessels of the perineum,
of the integument of the penis, and of the scrotum (or vulva), follow the
course of the external pudendal vessels, and end in the superficial inguinal
and subinguinal glands. Those of the glans penis vel clitoridis terminate
partly in the deep subinguinal glands and partly in the external iliac glands.
The visceral nodes
are associated with the branches of the celiac, superior and inferior
mesenteric arteries. Those related to the branches of the celiac artery form
three sets, gastric, hepatic, and pancreaticolienal.
The Gastric nodes
consist of two sets, superior
and inferior.
The Superior Gastric
nodes (lymphoglandulæ gastricæ superiores) accompany
the left gastric artery and are divisible into three groups, viz.: (a) upper, on the stem of the
artery; (b) lower,
accompanying the descending branches of the artery along the cardiac half of
the lesser curvature of the stomach, between the two layers of the lesser
omentum; and (c) paracardial
outlying members of the gastric glands, disposed in a manner comparable to a
chain of beads around the neck of the stomach (Jamieson and Dobson ). They receive their afferents from the stomach; their
efferents pass to the celiac group of preaortic glands.
The Inferior Gastric
nodes (lymphoglandulæ gastricæ inferiores; right
gastroepiploic gland), four to seven in number, lie between the two layers
of the greater omentum along the pyloric half of the greater curvature of the
stomach.
The Hepatic nodes
(lymphoglandulæ hepaticæ) consist of the following groups: (a)
hepatic, on the stem of the
hepatic artery, and extending upward along the common bile duct, between the
two layers of the lesser omentum, as far as the porta hepatis; the cystic nodes, a member of this
group, is placed near the neck of the gall-bladder; (b) subpyloric, four or five in
number, in close relation to the bifurcation of the gastroduodenal artery, in
the angle between the superior and descending parts of the duodenum; an
outlying member of this group is sometimes found above the duodenum on the
right gastric (pyloric) artery. The glands of the hepatic chain receive
afferents from the stomach, duodenum, liver, gall-bladder, and pancreas; their
efferents join the celiac group of preaortic glands.
The Pancreaticolienal
nodes (lymphoglandulæ pancreaticolienales; splenic glands) accompany the lienal (splenic) artery, and
are situated in relation to the posterior surface and upper border of the
pancreas; one or two members of this group are found in the gastrolienal
ligament (Jamieson and Dobson, op. cit.). Their afferents are derived
from the stomach, spleen, and pancreas, their efferents join the celiac group
of preaortic glands.
Lymphatics of stomach
Lymphatics
of stomach, etc. The stomach has been turned upward.
The
lymphatics of cecum and vermiform process from the front.
The
lymphatics of cecum and vermiform process from behind.
The superior
mesenteric nodes may be divided into three principal groups: mesenteric, ileocolic, and mesocolic.
The Mesenteric nodes
(lymphoglandulæ mesentericæ) lie between the layers of the
mesentery. They vary from one hundred to one hundred and fifty in number, and
may be grouped into three sets, viz.: one lying close to the wall of the small
intestine, among the terminal twigs of the superior mesenteric artery; a
second, in relation to the loops and primary branches of the vessels; and a
third along the trunk of the artery.
The Ileocolic nodes,
from ten to twenty in number, form a chain around the ileocolic artery, but
show a tendency to subdivision into two groups, one near the duodenum and
another on the lower part of the trunk of the artery. Where the vessel divides
into its terminal branches the chain is broken up into several groups, viz.: (a)
ileal, in relation to the
ileal branch of the artery; (b) anterior
ileocolic, usually of three glands, in the ileocolic fold, near
the wall of the cecum; (c) posterior
ileocolic, mostly placed in the angle between the ileum and the colon,
but partly lying behind the cecum at its junction with the ascending colon; (d)
a single gland, between the
layers of the mesenteriole of the vermiform process; (e) right colic, along the medial
side of the ascending colon.
Lymphatics
of colon.
The Mesocolic nodes
(lymphoglandulæ mesocolicæ) are numerous, and lie between
the layers of the transverse mesocolon, in close relation to the transverse
colon; they are best developed in the neighborhood of the right and left colic
flexures. One or two small glands are occasionally seen along the trunk of the
right colic artery and others are found in relation to the trunk and branches
of the middle colic artery.
The superior mesenteric glands receive afferents from the
jejunum, ileum, cecum, vermiform process, and the ascending and transverse
parts of the colon; their efferents pass to the preaortic glands.
The inferior
mesenteric nodes consist of: (a) small glands on the branches of
the left colic and sigmoid arteries; (b) a group in the sigmoid
mesocolon, around the superior hemorrhoidal artery; and (c) a pararectal group in contact with the
muscular coat of the rectum. They drain the descending iliac and sigmoid parts
of the colon and the upper part of the rectum; their efferents pass to the
preaortic glands.
The Lymphatic Vessels of the Abdominal and
Pelvic Viscera The lymphatic vessels of the
abdominal and pelvic viscera consist of (1) those of the subdiaphragmatic
portion of the digestive tube and its associated glands, the liver and
pancreas; (2) those of the spleen and suprarenal glands; (3) those of the
urinary organs; (4) those of the reproductive organs.
1. The lymphatic
vessels of the subdiaphragmatic portion of the digestive tube are
situated partly in the mucous membrane and partly in the seromuscular coats,
but as the former system drains into the latter, the two may be considered as
one.
The Lymphatic
Vessels of the Stomach are continuous at the cardiac orifice with those
of the esophagus, and at the pylorus with those of the duodenum. They mainly
follow the bloodvessels, and may be arranged in four sets. Those of the first
set accompany the branches of the left gastric artery, receiving tributaries
from a large area on either surface of the stomach, and terminate in the
superior gastric glands. Those of the second set drain the fundus and body of
the stomach on the left of a line drawn vertically from the esophagus; they
accompany, more or less closely, the short gastric and left gastroepiploic
arteries, and end in the pancreaticolienal glands. The vessels of the third set
drain the right portion of the greater curvature as far as the pyloric portion,
and end in the inferior gastric glands, the efferents of which pass to the
subpyloric group. Those of the fourth set drain the pyloric portion and pass to
the hepatic and subpyloric glands, and to the superior gastric glands.
The Lymphatic
Vessels of the Duodenum consist of an anterior and a posterior set,
which open into a series of small pancreaticoduodenal
glands on the anterior and posterior aspects of the groove between the
head of the pancreas and the duodenum. The efferents of these glands run in two
directions, upward to the hepatic glands and downward to the preaortic glands
around the origin of the superior mesenteric artery.
The Lymphatic
Vessels of the Jejunum and Ileum are termed lacteals, from the milk-white fluid they contain during
intestinal digestion. They run between the layers of the mesentery and enter
the mesenteric glands, the efferents of which end in the preaortic glands.
The Lymphatic
Vessels of the Vermiform Process and Cecum are numerous, since in the
wall of this process there is a large amount of adenoid tissue. From the body
and tail of the vermiform process eight to fifteen vessels ascend between the
layers of the mesenteriole, one or two being interrupted in the gland which
lies between the layers of this peritoneal fold. They unite to form three or
four vessels, which end partly in the lower and partly in the upper glands of
the ileocolic chain. The vessels from the root of the vermiform process and
from the cecum consist of an anterior and a posterior group. The anterior
vessels pass in front of the cecum, and end in the anterior ileocolic glands
and in the upper and lower glands of the ileocolic chain; the posterior vessels
ascend over the back of the cecum and terminate in the posterior ileocolic
glands and in the lower glands of the ileocolic chain.
Lymphatic Vessels of the
—The lymphatic
vessels of the ascending and transverse parts of the colon finally end in the
mesenteric glands, after traversing the right colic and mesocolic glands. Those
of the descending and iliac sigmoid parts of the colon are interrupted by the
small glands on the branches of the left colic and sigmoid arteries, and ultimately
end in the preaortic glands around the origin of the inferior mesenteric
artery.
2.
The lymphatic vessels of the spleen
and suprarenal glands.
3.
The lymphatic vessels of the urinary
organs.
(4)
The lymphatic vessels of the
reproductive organs.
The Lymphatic
Vessels of the Testes consist of two sets, superficial and deep, the
former commencing on the surface of the tunica vaginalis, the latter in the
epididymis and body of the testis. They form from four to eight collecting
trunks which ascend with the spermatic veins in the spermatic cord and along
the front of the Psoas major to the level where the spermatic vessels cross the
ureter and end in the lateral and preaortic groups of lumbar glands.
In pelvic
area differ the visceral and parietal lymphatic nodes.
The abdominal portion of the sympathetic trunk.
Abdominal
portion of the sympathetic trunk, with the celiac and hypogastric plexuses.
The
Hepatic Branches (rami
hepatici) arise from the left vagus: they join the hepatic plexus
and through it are conveyed to the liver.C:\Documents and Settings\xata\Application Data\gray\henry gray anatomy\www.bartleby.com\107\218.html
- i847
The
secondary plexuses springing from or connected with the celiac plexus are the
The ganglia lie on the
anterolateral surface of the lumbar vertebrae on the medial border of the psoas
major muscle. White communicating branches are sent only to the superior two or
three lumbar nerves.
Along its entire distance the abdominal part of the
sympathetic trunk sends off a great number of branches which, together with the
greater and lesser splanchnic nerves and the abdominal segments of the vagus
nerves, form the largest unpaired coeliac plexus (plexus
celiacus). Numerous spinal ganglia (C5-L3) also
take part in its formation. The coeliac plexus lies on the anterior
semicircumference of the abdominal aorta behind the pancreas and surrounds the
initial parts of the coeliac trunk (truncus celiacus) and the superior
mesenteric artery. It occupies an area between the renal arteries, the
suprarenal glands, and the aortic opening of the diaphragm and includes the
paired ganglion of the coeliac artery—coeliac ganglion (ganglion
celiacum), and sometimes the unpaired ganglion of the
superior mesenteric artery—superior mesenteric ganglion (ganglion
mesentericum superius) lying under the root of this artery.
The coeliac plexus also gives off some smaller paired
plexuses to the diaphragmT. suprarenals, and kidneys as well as the testicular
(ovarian) plexus (plexus testicularis [ovaricus])
extending along the course of the arteries of the same name. There are also a
series of unpaired plexuses which pass to some organs along the walls of arteries
whose names they are given. Among these is the superior
mesenteric plexus (plexus mesentericus superior) which
supplies the pancreas, the small intestine and the large intestine to half the
length of the transverse colon, and the ovary.
The second main source of innervation of the abdominal
organs is the plexus on the aorta—aortic plexus {plexus aorticus
abdominalis), formed by two trunks arising from the coeliac
plexus and branches running from the lumbar ganglia of the sympathetic trunk.
The aortic plexus gives rise to the inferior mesenteric plexus (plexus mesentericus inferior) for the
transverse, descending, and sigmoid colon, and the upper part of the rectum
(the superior rectal plexus, plexus rect.alis superior). At the origin of the
inferior mesenteric plexus lies the inferior mesenteric ganglion (ganglion
mesentericum inferius) whose postganglionic fibres pass to the
pelvis as components of the hypogastric nerves.
The aortic plexus is continuous with the unpaired
hypogastric plexus (plexus hypogastricus superior) which bifurcates at the
promontory of the sacrum and is in turn continuous with the pelvic plexus
(plexus hypogastricus inferior s. plexus pelvinus). Fibres derived from the
superior lumbar segments are functionally vasomotor (vasoconstrictor) in
relation to the penis and motor in relation to the uterus and the sphinter
urethrae muscle.
The sacral, or pelvic, part usually has four ganglia. Lying on the anterior
surface of the sacrum along the medial margin of the anterior sacral foramen,
both trunks gradually converge to terminate as one common unpaired ganglion impar on the
anterior surface of the coccyx. The ganglia of the pelvic part, like those of
the lumbar part, are connected both by small longitudinal and transverse
trunks.
From the ganglia of the sacral part of the sympathetic
trunk arise some in the pelvic plexus: (1) anteroinferior part in which
are distinguished a superior portion innervating the urinary bladder, the vesical plexus
(plexus vesi- calis) and an inferior portion supplying the
prostatic gland, the prostatic plexus (plexus prostaticus), the
seminal vesicles and ductus deferens, the plexus of the vas deferens (plexus deferentialis), and the
cavernous bodies, cavernous nerves of the penis (nervi cavernosi penis), (2) posterior part of the
plexus supplies the rectum, the middle and inferior rectal
plexuses (plexus rectales medii and infe- riores). A
third, middle
part, is distinguished, in addition, in females; its inferior
portion sends branches to the uterus and vagina, the uterovaginal
plexus (plexus uterovaginalis) and the
cavernous bodies of the clitoris, the cavernous nerves of the clitoris (nervi cavernosi
clitoridis), while the superior portion gives off branches to
the uterus and ovaries.
INNERVATION OF THE GASTRO INTESTINAL TRACT (TO
THE LEVEL OF THE SIGMOID COLON), PANCREAS, AND LIVER
The afferent
outflow from these organs occurs along fibres which are constituents of the
vagus and the lesser and greater splanchnic nerves, the hepatic and coeliac
plexuses, and the thoracic and lumbar spinal nerves, and, according to some
authors, also of the phrenic nerve.
The
sympathetic nerves conduct the sense of pain from these organs; the vagus nerve
conducts the other afferent impulses as well as the sense of nausea and hunger
from the stomach.
Efferent
parasympathetic innervation. Preganglionic fibres from the dorsal vegetative
nucleus of the vagus nerve pass as components of the last named to. the
terminal ganglia in the tissues of the organs discussed. In the intestine
these are the cells of the intestinal plexuses (the myenteric and submucous
plexuses). From the ganglia the postganglionic fibres run to the smooth muscles
and glands. Function: stimulation of peristalsis of the stomach, relaxation of
the pyloric sphincter, stimulation of peristalsis of the intestine and gall
bladder. The vagus nerve contains fibres which stimulate and inhibit secretion.
ESerent parasympathetic innervation is also concerned with dilation of vessels.
Efferent
sympathetic innervation. The preganglionic fibres emerge from the lateral horns
of the fifth to twelfth spinal segments and then pass in the corresponding
white communicating branches into the sympathetic trunk and then without
interruption, as components of the greater splanchnic nerves (between the
sixth and ninth ganglia), reach the intermediate ganglia contributing to the
formation of the coeliac and mesenteric plexuses. Here arise the postganglionic
fibres which as components of the coeliac and superior mesenteric plexuses
extend to the liver, pancreas, the small and large intestine and to the level
of the middle of the transverse colon; the left half of the transverse colon
and the descending colon are innervated by the inferior mesenteric plexus.
The plexuses mentioned supply the muscles and
glands of the organs discussed. Function: inhibition of gastric, intestinal and
gall bladder peristalsis, constriction of the blood vessels, and inhibition pf
glandular secretion.
It should be added that the movement
of the gastric and intestinal contents can also be delayed because the
sympathetic nerves cause active contraction of the pyloric, intestinal, and
other sphincters.
INNERVATION OF
THE SIGMOID COLON, RECTUM, AND URINARY BLADDER
The afferent
pathways run as components in the inferior mesenteric, superior and inferior
hypogastric plexuses, and in the pelvic splanchnic nerves.
Efferent
parasympathetic innervation. The preganglionic fibres arise in the lateral
horns of the second to fourth sacral spinal segments and emerge as components
of the corresponding anterior roots of the spinal nerves. They then pass as
the pelvic splanchnic nerves to the intraorganic ganglia of the parts of the
large intestine discussed and to the ganglia located around the urinary
bladder. All these ganglia give rise to the postganglionic fibres which reach
the smooth muscles of the organs. Function: stimulation of peristalsis of the
sigmoid colon and rectum, relaxation of the sphincter and internus muscle,
contraction of the detrusor urinae, and relaxation of the sphincter vesical
muscle.
Efferent
sympathetic innervation. The preganglionic fibres pass from the lateral horns
of the lumbar spinal cord through the corresponding anterior roots into the
white communicating branches, run without interruption through the sympathetic
trunk, and Beach the inferior mesenteric ganglion. In this ganglion arise the
postganglionic fibres which then extend as components of the hypogastric nerves
to the smooth muscles of the organs discussed. Function: inhibition of
peristalsis of the sigmoid colon and rectum and contraction of the sphincter
and internus muscle. The sympathetic nerves in the urinary bladder cause
relaxation of the detrusor urinae and contraction of the sphincter urethrae muscle.
Innervation of the reproductive
organs is discussed on (sympathetic) and (parasympathetic). The innervation of
the other internal organs is discussed in the sections dealing with their
description.
INNERVATION OF
THE BLOOD VESSELS
The extent
of innervation of the arteries, capillaries, and veins differs. Arteries with
well developed muscular elements in the tunica media are supplied with nerves
most richly, the veins are supplied less richly; the inferior vena cava and the
portal vein occupy an intermediate position.
The larger
vessels situated in the body cavities receive innervation from branches of the
sympathetic trunk, the nearest plexuses of the vegetative system, and the
adjoining spinal nerves; the peripheral vessels of the cavitary walls and the
vessels of the limbs are supplied by nerves passing close to them. Nerves
approaching the vessels run segmentally and form perivascular plexuses which
give off branches; after penetrating the wall these branches are distributed in
the adventitia.(tunica externa) and between it and tunica media. The fibres
supply the muscular structures of the wall for which purpose their terminations
are shaped differently. It has been proved to date that receptors are present
in all arteries, veins, and lymphatic vessels.
The first
neuron of the afferent outflow from the vascular system is in the
intervertebral ganglia or in the ganglia of the vegetative nerves (the
splanchnic and the vagus nerves); it then passes as a component of the
conductor of the interoceptive analyser . The
vasomotor centre is in the medulla oblongata. The globus pallidus, thalamus,
and tuber cinereum are concerned with the regulation of circulation. The higher
centres of circulation, like the centres of all vegetative functions, are
located in the cortex of the cerebral motor zone (the frontal lobe) and in
front and to the back of it. According to the certain data, the cortical centre
of the vascular function analyser is evidently found in all parts of the
cortex. The efferent connections of the brain with the stem and spinal centres
are evidently effected by the pyramidal and extrapyramidal tracts.
Closure of
the reflex arc may occur at all levels of the central nervous system. Some authors believe that it may
also be accomplished in the peripheral part of the nervous system through
Dogiel’s cells of the second type located in the ganglia of the vegetative
plexuses (the vegetative refiex arc proper).
The efferent
path causes a vasomotor effect, i.e. dilation or constriction of the vessels.
The vasoconstricting fibres pass in the sympathetic nerves, the vasodilating
fibres run. in all parasympathetic nerves of the cranial part of the vegetative
system (third, seventh ninth, and tenth pairs), in the posterior roots of the
spinal nerves (not all authors share this viewpoint), and in the
parasympathetic nerves of the sacral part (the splanchnic pelvic nerves).
There is
disagreement concerning efferent innervation of the capillaries. Some authors
claim that capillaries, being devoid of muscular elements, are also devoid of
the corresponding efferent innervation; others have described nerve endings on
capillaries located in the brain parenchyma (axovasal connections).
The parasympathetic centres lie in the spinal cord, in
the intermediolaterai
nucleus (nucleus
intermediolateralis) of the lateral horn at the level of
the second to fourth sacral segments.
THE PERIPHERAL PART OF THE PARASYMPATHETIC SYSTEM
The peripheral part of the cranial
parasympathetic system consists of the following
structures: (1)
preganglionic fibres passing in the
third, seventh, ninth, and tenth pairs of cranial nerves (according to
Mitchell, also in the first and eleventh pairs); (2) terminal ganglia lying close to the organs, namely, the
ciliary, sphenopalatine, submandibular, and optic ganglia, and (3) postganglionic fibres
which either stretch independently, e.g. the short
ciliary nerves arising from the ciliary ganglion, or pass in some other nerves,
e.g. postganglionic fibres originating from the otic ganglion and running in
the auriculotemporal nerve. Certain authors claim that the parasympathetic
fibres also emerge from different segments of the spinal cord through the
dorsal roots and pass to the walls of the trunk and the limbs
The peripheral part of the sacral
parasympathetic system consists of fibres which run in
the anterior roots of the second, third, and fourth sacral nerves, then in
their anterior branches forming the sacral plexus (somatic plexus) and finally
enter the true pelvis. In the pelvis they leave the plexus and as the pelvic splanchnic nerves
(nn. splanchnici
pelvini) pass to the pelvic plexus (plexus hypogastricus
inferior) together with which they innervate the pelvic organs (the rectum with
the sigmoid colon, the urinary bladder, and the external and internal
genitalia). Stimulation of the pelvic splanchnic nerves causes contraction of
the rectum and bladder (m. detrusor urinae) with relaxation of their sphincter
muscles. The fibres of the sympathetic hypogastric plexus, in contrast, delay
the evacuation of these organs; they stimulate uterine contractions, while the
pelvic splanchnic nerves inhibit it. The pelvic splanchnic nerves also contain
vasodilator fibres (nn.
erigentes) for the cavernous bodies of the penis and clitoris
which are responsible for erection. The parasympathetic fibres arising from the
sacral segment of the spinal cord extend to the pelvic plexuses not only in the
erigentes and pelvic splanchnic nerves but also in the pudendal nerve (the
preganglionic fibres). According to certain data, the pudendal nerve is a
complex nerve containing, in addition to somatic fibres, vegetative
(sympathetic and parasympathetic) fibres that form part of the inferior
hypogastric plexus. The sympathetic fibres arising from the ganglia of the
sacral segment of the sympathetic trunk as postganglionic fibres join the
pudendal nerve in the true pelvis and pass through the inferior hypogastric
plexus to the pelvic organs.
The intramural nervous system
also belongs to the parasympathetic nervous system.
The walls of some hollow organs contain nerve plexuses of
small ganglia (terminal) with ganglionic cells and non-medulated fibres; this
is the gang- liono-reticular, or intramural system.
This system has been studied most completely by Soviet
scientists (Dogel, Lavrentyev, Vorobyev, and Kolosov). Leontovich discovered a
diffuse nervous network in some tissues (“Leontovich’s network”). The intramural
system is particularly developed in the digestive tract where it is represented
by several plexuses.
1. The myenteric
(Auerbach’s) plexus {plexus myentericus
Auerbachii) lies between the longitudinal and circular muscles of the digestive
tube.
2. The submucous
(Meissner’s) plexus (plexus submucosus Meissneri)
is located
in the submucous tissue. It is continuous with the plexus of the glands and
villi. The “Leontovich’s network” is to the periphery of the above-named
plexuses.
The plexuses receive nerve fibres from the sympathetic
and parasympathetic systems. In the intramural plexuses the preganglionic
fibres of the parasympathetic systems are switched over to the postganglionic
fibres.
Lower
half of right sympathetic cord.
Assistant Galytsa-Harhalis
O.Ya.