The Sympathetic Nervous System

Autonomic nervous system .
Sympathetic Nervous System.
Sympathetic Trunk .
Plexus.

1. The Sympathetic Nervous
SystemTHE VEGETATIVE NERVOUS S YSTEM
THE PARASYMPATHETIC PART

2. Sympathetic Nervous System
1. lateral gray horns (T1-L2)
2. thoracolumbar outflow
3. ganglia
a. sympathetic trunk
(paravertebral)
b. Prevertebral (collateral)
4. preganglionic axons short
5. postganglionic axons long

3. The paired sympathetic trunk runs from the external
cranial base down to the coccyx. It comprises 20-25
ganglia of sympathetic trunk
Upon reaching
the coccyx, the
trunks merge
into a single
ganglion impar
The ganglia of
the sympathetic
trunk contain the
peripheral
efferent neurons
of the
sympathetic part
(multipolar
neurons).

4. spinal
nerve
dorsal
ramus
ventral
ramus
gray ramus
communicans
white ramus
communicans
sympathetic
ganglion
intermediolateral
gray column
Structure of spinal nerves: Sympathetic pathways

5. Sympathetic System: Postganglionic Cell Bodies
Paravertebral
ganglia
Prevertebral
ganglia
• celiac ganglion
• sup. mesent. g.
• inf. mesent. g.
aorta
sympathetic
trunk (chain)
1. Paravertebral ganglia
• Located along sides of vertebrae
• United by preganglionics into Sympathetic Trunk
• Preganglionic neurons are thoracolumbar (T1–L2/L3)
but postganglionic neurons are cervical to coccyx
• Some preganglionics ascend or descend in trunk
synapse at
same level
ascend to
synapse at
higher level
descend to
synapse at
lower level
Moore’s COA6 2010

6. Sympathetic System: Postganglionic Cell Bodies
Paravertebral
ganglia
Prevertebral
ganglia
• celiac ganglion
• sup. mesent. g.
• inf. mesent. g.
aorta
sympathetic
trunk (chain)
2. Prevertebral (preaortic) ganglia
• Located anterior to abdominal aorta, in plexuses
surrounding its major branches
• Preganglionics reach prevertebral ganglia via
abdominopelvic splanchnic nerves
Moore’s COA6 2010
abdominopelvic
splanchnic
nerve

7. Sympathetic System: Summary
Moore’s COA6 2010
T1
L2
somatic tissues
(body wall, limbs)
visceral tissues
(organs)
postganglionics
via 31 spinal
nerves
to somatic tissues
of neck, body wall,
and limbs
sympathetic
trunk
prevertebral
ganglia
Cardiopulmonary Splanchnics:
postganglionic fibers to thoracic
viscera
Abdominopelvic Splanchnics:
preganglionic fibers to
prevertebral ganglia,
postganglionic fibers to
abdominopelvic viscera

10. Moore’s COA6 2010
somatic tissues
(body wall, limbs)
visceral tissues
(organs)
Sympathetic System: Preganglionic Cell Bodies
• Preganglionic cell bodies in
intermediolateral gray
• T1 –L2/L3
• Somatotopic organization
intermediolateral
gray columns
lateral
horn
T1 –
L2/L3

11. Superior Cervical Ganglion
The superior cervical ganglion is located
posteriorly to the internal carotid artery, and
anterior to the C1-4 vertebrae. Several important
post-ganglionic nerves originate from here:
Internal carotid nerve –hitch-hikes along the
internal carotid artery, forming a network of
nerves. Branches from the internal carotid plexus
innervate structures in the eye, the
pterygopalatine artery and the internal carotid
artery itself.
External carotid nerve –hitch-hikes along the
common and external carotid arteries, forming a
network of nerves. It innervates the smooth
muscle of the arteries.
Nerve to pharyngeal plexus –combines with
branches from the vagus and glossopharyngeal
nerves to form the pharyngeal plexus.
Superior cardiac branch –contributes to the
cardiac plexus in the thorax.
Gray rami communicantes –join four upper
cervical spinal nervesC1-C4.

14. Middle Cervical Ganglion
It lies at the level of the transverse
processes of the C V and C VI
vertebrae. It is connected to the
superior cervical ganglion with one
interganglionicbranch and with the
inferior cervical ganglion with two
interganglionicbranches. They form
the ansasubclavia( loop of
Vieussens) it gives some branches
as follow –
a)The grey communicating
branches to the C IV –C VI
spinal nerves.
b)The common carotid nerve
forms the same plexus
c)The middle cervical cardiac
nerve takes part of the formation
the deep part of the extraorganic
cardiac plexus.

15. InferiorCervicalGanglion
Theinferiorcervicalganglionis
situatedanteriorlytotheC7
vertebra.Itisoccasionallyfused
withthefirstthoracicvertebrae,
formingthecervicothoracic
ganglion.Therearethreepost-
ganglionicfibresthatarisefrom
thisganglion:
•Grayramicommunicantes–
distributessympatheticfibresto
theanteriorramiofC7,C8and
T1.
•Branchestothesubclavian
andvertebralarteries–
Theseinnervatethesmooth
musclepresentinthearteries.
•Inferiorcardiacnerve–
contributestothecardiacplexus
inthethorax.

17. Ganglia Vertebral Level Arteries Involved Effector Organ(s)
Superior cervical
ganglion
C1-C4 Common, external and
internal carotid arteries
•Eyeball
•Face
•Nasal glands
•Pharynx
•Glands of the palate
and nasal cavity
•Salivatoryglands
•Lacrimal glands
•Sweat glands
•Pineal gland
•Dilator pupillae
•Superior tarsal muscle
•Carotid body
•Heart
•Arterial smooth muscle
Middle cervical ganglionC6 Inferior thyroid artery•Larynx
•Trachea
•Pharynx
•Upper oesophagus
•Heart
•Arterial smooth muscle
Inferior cervical ganglionC7 Vertebral and subclavian
arteries
•Heart
•Arterial smooth muscle
Summary Table
•

18. The thoracic part of sympathetic trunk comprises 10 to 12 thoracic
ganglia situated on the heads of ribs below the parietal pleura.
Posteriorly one can distinguish the posterior intercostal arteries and
veins. The thoracic ganglia give the following branches:
1. the grey communicating branchespass to the corresponding
intercostal branches
2. Thoracic cardiac branches
3. The visceral branches which take part in innervation of the
vessels and viscera of the thoracic cavity –
•Oesophageal branches
•Bronchial branches
•Pulmonary branches
4. The greater splanchnic nerve
5. The lesser splanchnic nerve
6, The lowest splanchnic nerve

19. The lumbar ganglia are situated on the anterolateral surfaces of the
lumbar vertebral bodies. Each lumbar ganglion has two types of
branches-
1.The grey communicating branches –to the lumbar nerves.
2.The lumbar splanchnic nerves which contain mostly preganglionic
fibersand go to the coeliac autonomic plexuses of the abdominal
cavity.
The sacral or pelvic part of the sympathetic trunk is situated on the
pelvic surface of the sacrum medial to the sacral foramina. They give
some branches-
1.The grey communicating branches –to the sacral nerves.
2.The sacral splanchnic nerves –which contain mostly
preganglionic fibres and proceed to the superior and inferior
hypogastric plexuses.

20. Vegetative plexuses of the abdominal aorta
The largest vegetative plexus is
the abdominal aortic plexus
which is located on the aorta
and consists of some primary
plexuses. They are-
The coeliac plexus
The superior mesenteric
plexus
The intermesentericplexus
The inferior mesenteric
plexus
The superior hypogastric
plexus

21. The coeliac plexus –it is unpaired and
lies at the origin of the coeliac artery .
There are two semilunar coeliac ganglia
( or one horse shoe shape ) within the
coeliac plexus. The coeliac plexus
receives branches from the –
1.Greater and lesser splanchnic
nerves ( sympathetic)
2.Thoracic and lumbar spinal nerves (
sensory)
3.Phrenic nerve ( sensory)
4.Vagusnerve ( parasympathetic )
A great number of nerve branches arise
from the celiac plexus and run in all
directions to form secondary plexuses.
They are-
The phrenic plexus
The hepatic plexus
The splenic plexus
The gastric plexus
The pancreatic plexus

22. The superior mesenteric plexus
Is situated at the origin of the superior
mesenteric artery. It is a complex of the ;
a)Superior mesenteric ganglion
b)Greater and lesser splanchnic
nerves and upper lumbar splanchnic
nerves (sympathetic)
c)Lumbar spinal nerves (sensory)
d)Vagusnerve (parasympathetic)
The secondary plexuses of the superior
mesenteric plexus are-
The pancreatic plexus
The jejunal and ileal plexus
The caecal plexus
The right colic plexus
The middle colic plexus

23. The intermesentericplexus is situated
between the superior and inferior
mesenteric plexuses . It is formed by –
a)Aorticorenalganglia
b)Greater and lesser splanchnic
nerves and lumbar splanchnic
nerves ( sympathetic )
c)Lumbar spinal nerves ( sensory)
d)Vagusnerve ( parasympathetic )
The secondary plexuses of the
intermesentericplexus are-
The renal plexus
The suprarenal plexus
The testicular or ovarian plexuses

24. The inferior mesenteric plexus lies
at the root of the inferior
mesenteric artery . It is formed by-
1.Inferior mesenteric ganglion
2.Greater and lesser splanchnic
nerves and lumbar and sacral
splanchnic nerves (sympathetic
)
3.Lumbar spinal nerves
(sensory)
4.The pelvic splanchnic nerves
(parasympathetic)
The secondary plexuses of the
inferior mesenteric plexus are-
The superior rectal plexus
The left colic plexus
The sigmoid plexus

25. The superior hypogastric
plexus lies below the
bifurcation of the abdominal
aorta. It is formed by –
1.Superior hypogastric
ganglion
2.lumbar and sacral
splanchnic nerves
(sympathetic )
3.Sacral spinal nerves
(sensory)
4.The pelvic splanchnic
nerves (parasympathetic)
The superior hypogastric
plexus does not give
secondary plexus.

26. THE PELVIC PLEXUS
The inferior hypogastric plexus
is paired and the continuation
of the unpaired superior
hypogastric plexus . It lies on
the posterior wall of the lesser
pelvis.
The secondary plexuses of the
inferior hypogastric plexus are-
•The rectal plexus
•The vesical plexus
•The prostatic plexus
•The uterovaginal plexus
•The plexus of the vas
deferens

27. Visceral Afferents and Referred Pain
Somatic sensation:
• conscious, sharp, well-localized
• touch, pain, temperature, pressure, proprioception
Visceral sensation:
• often unconscious; if conscious: dull, poorly-localized
• distension, blood gas, blood pressure, cramping, irritants
dorsal root ganglion
Visceral sensory nerves [GVA]
• run with sympathetic &
parasympathetic nerves
• cell bodies in dorsal root ganglion
• nerve ending in viscera

29. SYMPATHETIC RESPONSES