Anatomy of autonomic nervous system

1. Autonomic nervous system
By
Dr Manah Chandra Changmai

2. The autonomic nervous system represents the
visceral component of the nervous system.
It consists of neurones located within both the
central nervous system (CNS) and the
peripheral nervous system (PNS) and which are
concerned with the control of the internal
environment, through innervation of secretory
glands, and both cardiac and smooth muscle.
'Autonomic' is a convenient rather than
appropriate title, since the functional
autonomy of this part of the nervous system is
illusory.
The autonomic activities is expressed by
regulation
ofbodytemperature,bloodpressure,cardiorespirato
ry rate gastro-intestinal motility and
glandular secretion
The autonomic nervous system

3. Plan of autonomic nervous system

4. Autonomic afferent pathways resemble
somatic afferent pathways.
The cell bodies of autonomic afferent origin
are unipolar neurones located in cranial and
dorsal root ganglia.

Their peripheral processes are distributed
through autonomic ganglia or plexuses, or
possibly through somatic nerves, without
interruption.
Autonomic afferent

5. Autonomic afferent

6. Autonomic efferent pathways differ from their somatic equivalents in that the
former are interrupted by peripheral synapses, there being a sequence of at
least two neurones between the CNS and the target structure
These are referred to as preganglionic and postganglionic neurones.
Autonomic nervous system
Sympathetic system Parasympathetic system
Visceral efferent

7. Autonomic efferent

8. somatic efferents autonomic efferents
1.Motor fibres consists of single
set of neurons and reach effector
Cell directly
1.Motor fibres consists of two
successive sets,preganglionic and
postganglionic,before reaching
effector cell
2.Target cells belong to one type-
striated or skeletal muscle
2.Target cells consists of three
types-cardiac muscle,smooth
muscle and glandular cell.
3.Stimulation of target cell cause
excitation only
3.Stimulation of target cells cause
either excitation or inhibition.
4.Activity of target cell completely
dependent on intact motor supply
4.Activity of target cells not
completely on nerve supply;i e
postdenervational hypersensitivity
of smooth muscle
5.Form plexuses close to CNS5.Form plexuses close to target .

9. Difference between somatic and autonomic motor neuron

10. Sympathetic system
The preganglionic motor neurons of sympathetic
system are located in lateral horn cells of all thoracic
and upper two lumbar vertebrae
Also known as thoraco-lumbar outflow.
The postganglionic sympathetic neurons consists of
lateral ,collateral and terminal ganglia.
-The lateral ganglia are the two sympathetic trunks
-The collateral ganglia are prevertebral in position and
represented by coeliac,superior mesentric,inferior
mesentric superior hypogastric ganglia.
The terminal ganglia of sympathetic system is found
only in suprarenal medulla.
Lateral horn of spinal cord
(T1 – L2 or L3)

11. Thoraco-lumbar outflow
Sympathetic/Parasympathetic

12. Sympathetic system

13. Sympathetic system is also called adrenergic system
because post ganglionic sympathetic fibres liberate
adrenaline.But sympathetic fibres to sweat glands of
hairy skin are cholinergic.
The entire function of sympathetic is a nerve of emergency
and during stress and strain to ‘Fight,Fright or Flight’.It is a
catabolic nerve and works for today.
In sympathetic system,the preganglionic fibres are
short and post ganglionic fibres are long.One
preganglionic fibre make synaptic connections with
twenty or more postganglionic neurons
Preganglionic sympathetic fibres
Postganglionic sympathetic fibres
Sympathetic system

14. Autonomic motor neurons

15. Anatomy of sympathetic system
It presents definite anatomical entity
Consists of a pair of ganglionated trunk,their
rami of communications,branches,plexuses
and subsidiary ganglia
Ganglionated trunk
-Paravertebral in position,extends from base of the
skull to the first coccygeal vertebrae.
-The trunk presents
Three ganglia in cervical part:Superior
Middle
Inferior
Eleven ganglia in thoracic part
Four lumbar
Four sacral ganglia.

16. Thoracic and upper two lumbar sympathetic ganglion
is connected to corresponding spinal nerve by both
white and grey rami communicans.
Above the 1
st
thoracic and below 2
nd
and 3
rd
lumbar
are connected to corresponding spinal nerves only
by grey rami communicans.
Grey rami convey post-ganglionic sympathetic fibres
from lateral ganglia through 31 pairs of spinal nerve.
Plexuses form by this nerves supply sudomotor,pilo
motor and vasoconstrictor fibres.

17. White ramus
Grey ramus
Post ganglionic neuron
Sympathetic ganglion
Spinal nerve
Planning of sympathetic nerve supply

18. white rami Grey rami
1.Lateral in position 1.Medial in position
2.Convey preganglionic motor
And viscero sensory fibres
2.Convey postganglionic fibres only
3.Connected to lateral ganglia
from T1 – L2 spinal nerves
3.Connected to all 31 pairs of spinal
nerve
4.Inresegmental in distribution4.Segmental in distribution and supply
Sudomotor,Pilomotor and
vasoconstrictor fibres of the body wall.

19. The parasympathetic system
The preganglionic motor neurons are partly
Located in the brainstem in connection with
-3
rd
cranial nerve(oculomotor)
-7
th
cranial nerve(facial)
-9
th
cranial nerve(glossopharyngeal)
-10
th
cranial nerve(vagus)
Partly in the lateral horn cells of 2
nd
to 4
th
sacral
segments of the spinal cord.
It is also known as cranio-sacral outflow
Postganglionic para-sympathetic neurons consists
of collateral and terminal ganglia.

21. Postganglionic parasympathetic fibres liberate
Acetyl-choline on effector cell,also known as
Cholinergic system.
Both sympathetic and parasympathetic
preganglionic fibres liberate acetylcholine.
The preganglionic fibres are longer than
postganglionic fibres.One preganglionic neurons
one or two post ganglionic neuron.
The action of parasympathetic is localise and
accurate.
Afferent parasympathetic fibres convey general
visceralsensationlikehunger,thirst or
nausea,distension of bladderEtc.
The cell bodies are located in the ganglia IX and
X cranial nerve and dorsal root ganglia of 2
nd

to4th sacral nerves. Preganglionic nerve fibre
Postganglionic nerve fibres

22. Parasympathetic fibres

23. Fibres of autonomic nervous system

24. Actions of parasympathetic system
Actions are localised and accurate.
On stimulation,
-the heart rate is diminished,
-The blood pressure falls,
-Pupil are constricted
-The peristalsis and glandular secretion
of alimentary tract are promoted.
-The urinary bladder and rectum are
evacuated.
It is anabolic in function and works for tommorow
because constriction of the pupil after parasympat-
thetic stimulation permits distant vision which sym
bolises activities of the future.
The parasympathetic system is essential
to our life.i.e;micturition is essentially a controlled
by parasympathetic,both filling and evacuation.

25. Autonomic nervous supply of some important organ
The Eye ball
-Sphincter pupillae by parasympathetic nerves
Preganglionic neurons located in Edinger
Westpal nucleus.
-Dilator pupillae supplied by sympathetic nerves
Preganglionic neurons located in lateral horn of
1
st
thoracic segment.
Horner’s syndrome
-Interruption of sympathetic supply to head and
neck results in horner syndrome
a)Constriction of pupil
b)Drooping of upper eyelids(ptosis)
c) Reduced prominence of the eyeball(Enopthalmos)
d)Absence of sweating on face and neck (anhydrosis)
e) Flushing of the face.

26. The facial nerve contains preganglionic
parasympathetic axons of neurones with their somata
in the superior salivatory nucleus
Preganglionic fibres are conveyed to the submandibular
ganglion, where they synapse on ganglionic neurones.
Postganglionic fibres innervate the submandibular and
sublingual salivary glands and are said to travel in the lingual
nerve.
Salivary gland
Submandibular and sublingual glands

27. The glossopharyngeal nerve contains preganglionic
parasympathetic secretomotor fibres for the parotid gland.
Originate in the inferior salivatory nucleus and travel in the
glossopharyngeal nerve and its tympanic branch.
Postganglionic fibres pass by communicating branches to the
auriculotemporal nerve, which conveys them to the parotid
gland.
Parotid gland

28. Nerve supply of Parotid gland

29. Autonomic nerve supply
Of heart

30. Cardiac plexus

31. The vagal nucleus (dorsal motor nucleus of the vagus) in
the medulla is a major source of preganglionic
parasympathetic fibres.
Efferent fibres travel in the vagus nerve and its
pulmonary, cardiac, oesophageal, gastric, intestinal and
other branches.
They synapse in minute ganglia in the visceral walls.
Gastrointestinal tract

32. Vagus nerve

34. Pelvic splanchnic nerves to the pelvic viscera travel
in anterior rami of the second, third and fourth
sacral spinal nerves.
The pelvic splanchnic nerves are motor to the muscle
of the rectum and bladder wall but inhibitory to the
vesical sphincter.
They supply vasodilator fibres to the erectile tissue of
the penis and clitoris and are probably also vasodilator
to the testes, ovaries, uterine tubes and uterus.
Pelvic sphlanic nerve
Pelvic splanchnic nerves

35. Thank you