Comparison of somatic and autonomic
systems
l
Effectors (Targets)
l
l
l
Somatic = skeletal muscle
Autonomic = smooth/cardiac muscle & glands
Efferent pathways
l
l
Somatic = no ganglia; myelinated axon from ventral
horn of cord all the way to effector
Autonomic = 2 neuron pathway; first is preganglionic
and body resides in brain/S.C.; 2nd is postganglionic
and body resides in autonomic ganglion
l
l
l
Pre’s are lightly myelinated; post’s are unmyelinated
SNS = short pre/long post ganglionic axon
PsNS = long pre/short post ganglionic axon
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Comparison of somatic and autonomic
systems
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Anatomical
Differences
l
l
l
Issue from different
regions of the CNS
Sympathetic - aka
the thoracolumbar
division
Parasympathetic –
aka the
craniosacral
division
Figure 15.3
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Anatomical Differences
l
Length of postganglionic fibers: sympathetic are
long and parasympathetic are short
l
Branching of axons: sympathetic axons are highly
branched to influence many organs while
parasympathetic axons have few branches so
have a localized effect
l
Sympathetic release norepinephrine (adrenergic)
l
Parasympathetic release acetylcholine
(cholinergic)
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Anatomical Differences
Figure 15.4a
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Anatomical Differences
Figure 15.4b
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Comparison of Somatic and Autonomic Systems
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Sympathetic Pathways to the Body Periphery
l
Innervate – sweat glands, arrector pili muscles,
and peripheral blood vessel
l
Preganglionic fibers enter the sympathetic trunk
ganglia nd synapse there with ganglionic cell
bodies
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To the Body Periphery
Figure 15.9
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Table 15.1
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Sympathetic Trunk Ganglia
l
Located on both sides of the vertebral column
l
Linked by short nerves into sympathetic trunks
l
Joined to ventral rami by white and gray rami
communicantes
l
About one sympathetic trunk ganglion for each
spinal nerve
- fusion of ganglia à fewer ganglia (22
(22--24
24)) than spinal
nerves
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Sympathetic Trunk Ganglia
Figure 15.8
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Collateral Ganglia
l
Or prevertebral ganglia differ in 3 ways:
1) unpaired, and not segmentally arranged
2) occur only in abdomen and pelvis
3) lie anterior to the vertebral column, mostly on
the abdominal aorta
l
Main ganglia – celiac, superior mesenteric, inferior
mesenteric, and inferior hypogastric ganglia
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Sympathetic
Division
Figure 15.7
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PELVIC INNERVATION
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PERLVIC
INNEVATION
Figure 15.13
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Pelvic Autonomics
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Sympathetic System
Pelvic Part of the Sympathetic Trunk
it is continuous above, behind the common iliac
vessels, with the abdominal par ..It
It runs down
behind the rectum on the front of the sacrum,
medial to the anterior sacral foramina. It has
four or five segmentally arranged ganglia.
Below, the two trunks converge and finally unite
in front of the coccyx forming a median ganglion
the ganglion impar
Branches
1-Gray rami communicantes to sacral and
coccygeal nerves
2-Fibers that join the hypogastric plexuses
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pelvic splanchnic nerves:
These are slender ,pass from the third and fourth or
second and third anterior rami to the inferior
hypogastric plexuses. They consist of
preganglionic parasympathetic fibers that are
distributed through the peripheral parasympathetic
ganglia to the pelvic viscera some fibers ascend
through the hypogastric plexuses and then via the
aortic plexus to the inferior mesenteric plexus. The
fibers are then distributed along branches of the
inferior mesenteric artery to supply the large bowel
from the left colic flexure to the upper half of the
anal canal
l
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Supply motor fibers to :
l 1 -Left third of transverse colon ,left colic
flexure , descending colon , sigmoid colon
l 2-Urinary bladder
l Inhibitory to uterus and uterine tube
l Vasodilatation fibers to erectile tissues of
penis or clitoris
l
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Superior Hypogastric Plexus: It is situated in front
of promontory of sacrum it is formed as a
continuation of aortic plexus and from branches of
third and fourth lumbar sympathetic ganglia. It
contains sympathetic and sacral parasympathetic
nerve fibers and visceral afferent nerve fibers.
superior hypogastric plexus divides inferiorly to
form right and left hypogastric nerves.
nerves.
Inferior Hypogastric Plexuses:each
Plexuses:each of these
surrounds corresponding internal iliac artery and
recieves branches from upper sacral ganglia of
sympathetic trunk .the main plexus divides into
subsidiary plexuses along the branches of internal
iliac artery(mainly the visceral,includes : middle
rectal, vesical, prostatic, vaginal and uterine
plexuses),these plexuses receives branches from
pelvic splanchnic nerves
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Sympathetic System
l
Lumbar splanchnic nerves:
Sympathetic.
From lumbar plexus to:
Abdominal sympathetic plexus.
Inferior mesenteric ganglion.
Superior hypogastric plexus:
To uterine tubes in female.
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Sympathetic System
l
Sacral sympathetic trunk:
Paravertebral ganglia.
Ganglion impar:
Coccygeal ganglion.
Superior hypogastric:
Sympathetic.
From lumbar and sacral splanchnic
nerves.
Feed into inferior hypogastric plexus.
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Sympathetic System
l
Sacral sympathetic trunk:
Paravertebral ganglia.
Inferior hypogastric plexus:
Mixed parasympathetic.
In males innervates urethra, ductus
deferens, prostate gland, and ejaculatory
ducts.
In females, innervates urethra and produces
uterovaginal plexus.
Produces vesicle plexus (urinary bladder).
Supplies rectum.
Uterovaginal plexus (uterus, vagina, ovaries.
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Parasympathetic System
l
Pelvic splanchnic nerves
Parasympathetic.
S2-4.
Feed into inferior hypogastric plexus.
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Parasympathetic System
l
Inferior hypogastric plexus:
In females:
Innervates:
Urethra.
Rectum.
Produces:
Uterovaginal plexus (uterus, vagina,
ovaries).
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Innervation of the Bladder
l
Sympathetics
l
l
T12
12,, L1
L1, L2
L2
Parasympathetics
Pelvic splanchnic nerves
l Nervi erigentes
l S 2, 3, 4
l
l
Nociceptive afferents
Sacral roots (S 2, 3, 4)
l Not sympathetics
l
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Innervation of Uterus, Cervix
and Ovaries
l
Uterovaginal plexus from superior and
inferior hypogastric plexuses
l
l
l
Sympathetic, parasympathetic and somatic
afferent
Fundus and body (intraperitoneal) - Inferior and
superior hypogastric plexuses
Cervix (subperitoneal)
Inferior hypogastric plexus to pelvic (splanchnic)
nerves (S2
(S2-S4) (most texts)
l Bonica: LUS and CX same as fundus
l
l
Ovaries - afferents with hypogastric
plexuses (T10
(T10--11)
11)
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Innervation of the Vagina
l
Superior 3/4ths
Uterovaginal plexus
l Pelvic plexus (sacral fibers)
l
l
Lower 1/4th
l
l
Pudendal nerve via sacral fibers
Perineum
l
Pudendal nerve
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Innervation of Prostate, Testes and
Scrotum
l
Prostate
Prostatic plexus
l Inferior hypogastric plexus
l
Testicle (T10
(T10))
l Vas deferens (T10
(T10--L1)
l Epididymis (T11
(T11--12
12))
l Prostate (Prostatic plexus; similar to
bladder)
l Scrotum
l
Ilioinguinal and genitofemoral
l Perineal nerve (branch of pudendal)
l
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Rectum, Anus and Perineum
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Sympathetics
l
l
Parasympathetics
l
l
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Pudendal nerve (somatic)
Also with pelvic splanchnic nerves
Anus
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Pelvic splanchnic nerves
Nociceptive afferents
l
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Superior and inferior hypogastric plexuses
Inferior rectal nerve via pudendal
Perineum by pudendal and branches
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Innervation of Pelvic Organs
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