done by: tymaa al-zaben & amin al-ajalouniautonomic versus somatic ns • notice that the ans...
TRANSCRIPT
Done by:
Tymaa Al-zaben & Amin Al-ajalouni
** Hello SERTONIN!
note:: the slide included within the sheet but make sure back to slide for pictures
SLIDE 3
The Autonomic Nervous System
Function : Regulate activity of smooth muscle, cardiac muscle
& certain glands .
Structures involved :
1- general visceral afferent neurons (GVA)
2- general visceral efferent neurons (GVE)
3-integration center within the brain "control center in hypothalamus and
other system such as limbic system"
Receives input from limbic system and other regions of the cerebrum.
SLIDE4
Autonomic versus Somatic NS Somatic nervous system
Afferent : consciously perceived sensations.
Effectors : excitation of skeletal muscle.
Efferent : one neuron from CNS, cell body either in anterior horn of spinal
cord in spinal nerve OR motor nuclei of cranial nerve axon exit directly
toward effectors organ( Skeletal muscles).
Autonomic nervous system
Afferent : unconsciously perceived visceral sensations.
Effectors : involuntary inhibition or excitation of smooth muscle, cardiac
muscle or glandular secretion.
Efferent : two neurons needed to connect CNS to organ .
preganglionic "cell body in CNS" and its axon exit toward target which is
postganglionic neurons and its axon exit toward effectors.
SLIDE 5
Autonomic versus Somatic NS • Notice that the ANS pathway is a 2 neuron pathway
while the Somatic NS only contains one neuron.
** The major Neurotransmitter is ACh, exception in sympathetic-post ganglionic
neuron which is Epinephrine.
SLIDE 6
Comparison of Somatic and Autonomic Nervous Systems
please back to slide to read the table SLIDE 7
Basic Anatomy of Motor ANS Preganglionic neuron
cell body inside brain or spinal cord
axon is myelinated type B fiber that extends to autonomic ganglion
neurotransmitter :ACh
Postganglionic neuron
cell body lies outside the CNS in an autonomic ganglion
axon is unmyelinated type C fiber that terminates in a visceral
effectors
neurotransmitter :ACh+ epinephrine
SLIDE 8
Divisions of the ANS
2 major divisions
1-Sympathetic (thoracolumbar) division
*preganglionic cell bodies in thoracic and first 2 lumbar
segments of spinal cord "anteriomedial cell column in lateral horn of spinal
cord" and it is the only area where the preganglion of sympathetic is present.
2-Parasympathetic (craniosacral) division
** two part 1- cranial part 2- spinal part ((sacral region))
preganglionic cell bodies in nuclei of 4 cranial nerves and the sacral
spinal cord (S2-S4) and same area of sympathetic "anteriolateral horn" exit
with spinal nerve .
## Both sympathetic ¶sympathetic Dual((double )) innervated different
organ "viscera " :
we mean in dual innervations ; same organ innervated by sympathetic and
parasympathetic^^opposite action ^^.
-one speeds up organ and one slows down organ
*Sympathetic NS increases heart rate
* Parasympathetic NS decreases heart rate
SLIDE 9
Sympathetic Division
application to that ...
*sympathetic innervate more structures and more organs than
parasympathetic .
*so parasympathetic is more specific in action than sympathetic
that is why parasympathetic for normal physiological situation and opposite
to it sympathetic in emergence situation ..
• A single sympathetic preganglionic fiber has many axon collaterals
and may synapse with 20 or more postganglionic neurons.
• The postganglionic axons typically terminate in several visceral
effectors and therefore the effects of sympathetic stimulation are
more widespread than the effects of parasympathetic stimulation.
SLIDE 10
Structure of the Sympathetic Division
Autonomic ganglion
preganglion
post ganglion
Sympathetic
shorter Longer -Near to CNS &direct parallel to vertebral column
parasympathetic
longer Shorter -connection near the wall of organ its self
Thoracolumbar division
• Preganglionic neurons originate from the thoracic and
lumbar levels of the spinal cord (T1‐L2)
IN The lateral horn (intermediolateral column (IML))
Sympathetic ganglia: post ganglion present outside CNS in autonomic
ganglia "sympathetic ganglia"
**types of sympathetic ganglion:
1) Paravertebral ganglia:
we are talk about Sympathetic trunk (vertebral chain) ganglia which direct
parallel to vertebral column.
2)Prevertebral (collateral) ganglia:
present in abdominopelvic region, or organs innervated by sympathetic NS in
abdomen &pelvis where the post ganglion present there.
example :
'note that the name of them referral to the name of major branches of
abdomen aorta' .
celiac, superior mesenteric, inferior mesenteric, aorticorenal
**SO preganglionic in spinal cord 'thoracic region' and postganglionic either in
sympathetic trunk or preverbal column.
SLIDE 11
Pathway from Spinal Cord to Sympathetic Trunk Ganglia:
• Preganglionic axons → anterior root of a spinal nerve → white ramus
→ sympathetic trunk ganglion.
**cell body of Preganglion in lateral horn of S.C exit S.C with ventral root of
spinal nerve & unit with ventral root ..
**spinal nerve exit by intervertebral foramen, outside vertebral column gives
branch:
Dorsal ,ventral, rami communicant(white +gray)
White rami communicantes transmitted fiber of Preganglion neuron outside
S.C toward sympathetic trunk.
• White rami communicantes: structures containing
sympathetic preganglionic axons that connect the anterior ramus
of the spinal nerve with the ganglia of the sympathetic trunk.
SLIDE 12
Fate of Preganglionic Neurons in Sympathetic Trunk
What will happen to pre ganglion fiber ??
Options :
1. Synapse in the post sympathetic ganglion of sympathetic trunk at the same
level (at level of entry).
2. Ascend up or descend in the sympathetic trunk and then synapse with
postganglionic neouron in ganglia (above) or (below) ..
to serve structure above\below thoracic ; we know that the pre ganglion of
sympathetic present only in thoracic and upper lumber so we need to provide
another structure ..
3. Continue, without synapsing, through the sympathetic trunk
ganglion to end at a prevertebral ganglion(anterior to abdomen aorta)
and synapse with post in it .
Innervating viscera in the abdominopelvic cavity
exit Via abdominopelvic splanchnic nerves ' above
diaphragm '
4. Pass through the sympathetic trunk ganglion and a prevertebral ganglion
and then to the adrenal medulla 'the cells of medulla serve as post ganglionic'.
SLIDE 13
Organization of Sympathetic Trunk Ganglia
Two sympathetic trunks along the vertebral column(both side)
Each sympathetic trunk ganglia has: 3 cervical(sup,mid,inf),11or12 thoracic,
4 or 5 lumbar, 4 or 5 pelvic and both trunks end caudally in one joint
ganglion (ganglion impar) بلتقوا مع بعض بالنهاية وبشكلوا
Postganglionic neurons from
the superior cervical ganglion ‐head and heart.
the middle cervical ganglion and the inferior cervical ganglion ‐heart.
Thoracic sympathetic trunk‐ heart(upper part of thoracic)
, lungs, and bronchi.
so keep in your minde
HEAD== Upper Cervical
HEART==Mid & Inf Cervical & Upper part of Thoracic
SLIDE 14
Pathways from Sympathetic Trunk Ganglia to Visceral Effects
The axons for the sympathetic nervous system are 4:
1-spinal 2-cephalic periarterial 3-sympathetic nerves 4-splanchnic nerves
The territory of the sympathetic nervous system:
All viscera
Blood vessels
Erector pili muscles
Which means that the sympathetic nervous system needs to reach all over the
body (somatic regions)
*Unlike the parasympathetic which only reaches the viscera
Which also means that the easiest way to reach all somatic areas is by the spinal
nerves
So the spinal nerves will carry with their (somatic afferents and efferents)post
ganglionic sympathetic fibers
The cephalic periarterial nerves will go the head and neck regions
The sympathetic nerves are considered direct postganglionic nerves from the
sympathetic trunk that will go to the viscera of thoracic or cervical region
And the splanchnic like we said contain preganglionic fibers that will go toward
the prevertebral ganglion .
SLIDE 15
THE SPINAL NERVES:
Gray ramus: Axons of some postganglionic neurons leave
the sympathetic trunk by entering a short pathway called a gray ramus
and merge with the anterior ramus of a spinal nerve .
Blood vessels (vasomotion), arrector mm. (pilomotion), and
sweat glands (sudomotion) ..
Gray rami communicantes: structures containing
sympathetic postganglionic axons that connect the ganglia
of the sympathetic trunk to spinal nerves.
Like we already mentioned that the spinal nerves intermediolateral cell columen
will give preganglionic sympathetic fibers which will go to the spinal never then
to the sympathetic trunk via the white communicants, after it reaches the trunk
it will synapse with the ganglia there and the postganglionic fibers from the
ganglia will go back again to the spinal nerves via the gray communicants, which
will then innervate all the somatic regions via the spinal nerves.
SLIDE 16
CEPHALIC PERIARTERIAL NERVES:
Some sympathetic preganglionicneurons that enter the sympathetic trunk
ascend to the superior cervical ganglion where they synapse
with postganglionic neurons Some of these leave the
sympathetic trunk by forming cephalic arterial nerves.
Serve visceral effectors in the skin of the face and head and iris (dilator)
Like we know we don’t have spinal nerves in the head region, we only have
cranial nerves
And we also don’t have white or gray communicants in head region
So how will we get sympathetic innervation to the head region?
The superior cervical ganglion will receive efferent sympathetic fibers thro white
communicants and it will synapse in the ganglia, then the postganglionic fibers
will leave as the cephalic periarterial (around blood vessesl) (they will use the
arteries like the carotid and form plexuses around them) nerves after they
become close with their target they will jump from being close to arteries
(periarterial) to the cranial nerves, ex:deep petrosal nerves which was considered
cephalic periarterial nerve until it reached pterygoid canal and joined the great
petrosal and formed the nerve of pterygoid canal
SLIDE 17
THE SYMPATHETIC NERVES:
Some axons of the postganglionic neurons leave the trunk by forming
sympathetic nerves (Cardiopulmonary splanchnic nerves)
Innervate the heart and lungs.
Serves all viscera above diaphragm tqreebn (in thoracic region and cervical) (like
heart lungs….)
It is formed in this pattern
Preganglionic sympathetic fibers going to the sympathetic trunk via white
communicants then synapsing with any ganglia in the trunk either at same level
or not, then those postganglionic fibers will leave as the sympathetic nerves
A student asked: how will the superior cervical innervate the heart?? Doctors
answer: 3adi it descends down to the heart but before reaching the heart it
forms a plexus (cardiac plexus)
SLIDE 18
SPLANCHNIC NERVES:
# Some sympathetic preganglionic axons pass through the sympathetic trunk
without terminating in it. Beyond the trunk they form nerves called splanchnic
nerves which extend to prevertebral ganglia
1. T5‐T9 or T10‐ Greater splanchnic nerve
2. T10‐T11‐ Lesser splanchnic nerve
3. T12‐ least splanchnic nerve
4. L1‐L4‐ Lumbar splanchnic nerve
They leave the sympathetic trunk as preganglionic fibers!!! Which means they
don’t synapse in the sympathetic ganglias (important to remember) and they
will go toward the prevertebral ganglia
They are from t5-t12 but sometimes we can say we have lumbar splanchnic
nerves too
We have greater splanchnic nerves, lesser splanchnic never, least splanchnic
nerves which all originate above the diaphragm and penetrate the diaphragm
down to the abdomen mainly from the cruras of diaphragm so they can reach the
prevertebral ganglia
SLIDE 20
Splanchnic Nerves to the Adrenal Medulla
Some sympathetic preganglionic axons pass, without synapsing, through the
smpathetic trunk, greater splanchnic nerves and celiac ganglion into the adrenl
medulla (modified sympathetic ganglia).
Release hormones into blood
• 80% epinephrine, 20% norepinephrine.
But also put in mind that not all splanchnic nerves will terminate in the
prevertebral ganglia, some of them may continue to the adrenal glands (medulla)
and synapse there to help secrete epinephrine and norepinephrine
SLIDE 19
THE PREVERTEBRAL GANGLIA:
We have 4 ganglias : celiac, aorticorenal, superior mesenteric, inferior
mesenteric
All of theseganglias receive preganglionic fibers from splanchnic nerves then
synapse and give postganglionic fibers to the abdominopelvic organs
Note: all viscera is supplied by what we call plexuses which contains sympathetic
and parasympathetic fibers like (thoracic, cranial)
SLIDE 22
AFFERENT SYMPATHETIC FIBERS:
Viscera → sympathetic ganglion → white rami communicants → spinal nerve →
dorsal root ganglion → spinal cord
Theres a lil different between somatic and autonomic afferents, the autonomic
afferents perception is lower than somatic perception, less sensitivity, less in
number, and less receptors.
Mainly they are end nerves neurons and they carry a lot of modalities
These afferent fibers will go back the same way they came as simple as that but
when they reach the nerve level they will go to the dorsal root ganglia of spinal
cord and this is why we have what is called referral pain when we have visceral
damage because of the meeting between visceral afferents and somatic afferents
in the dorsal root ganglia
So the visceral referral pain depends on the entrance into the spinal cord so if a
sympathetic afferent of an organ entered at the level of t3-t5 the referral pain
will be mostly in dermatomes innervated by t3-t5
SLIDE 21
ORGANS INNERVATED BY SYMPATHETIC SYSTEM:
Structures innervated by each spinal nerve
sweat glands, arrector pili mm., blood vessels to skin & skeletal mm.
Thoracic & cranial plexuses supply:
heart, lungs,esophagus & thoracic blood vessels.
plexus around carotid artery to head structures.
Splanchnic nerves to prevertebral ganglia supply:
GI tract from stomach to rectum, urinary & reproductive organs.
Sorry for any mistakes
"Difficult Roads often leads to beautiful destinations"
THE END <3