The parasympathetic nervous system has preganglionic fibers that originate in the brainstem and sacral spinal cord and connect to postganglionic neurons in ganglia near target organs. Preganglionic fibers are long and travel via cranial nerves or sacral spinal nerves, while postganglionic fibers are short and stimulate glands and smooth muscles to increase activity of digestive, reproductive and urinary systems at rest. Damage to pelvic splanchnic nerves can impair bladder and sexual function.

1. Parasympathetic Nervous
System
THE VEGETATIVE NERVOUS SYSTEM
THE PARASYMPATHETIC PART

3. The autonomic nervous
system is a part of the CNS,
which works independently,
free from human influence
but under the control of the
CNS. The CNS controls
intelligence.
The autonomic nervous
system works autonomously.
The autonomic nervous
system coordinates and
adapts by the nerve and
humoral way the activity of all
organs, takes part in
preservation of the dynamic
balance of living functions.

4. Overview of the Autonomic Nervous System
Differences between Sympathetic & Parasympathetic
Target /ˈtɑːɡɪt/ Tissues
Sympathetic Parasympathetic
CENTRES In the spinal cord In the brain and spinal
cord
FUNCTION Feeding of tissues Protective , secretive
FIBRES Preganglionic axons are
short, postganglionic are
long
Preganglionic axons are
long , postganglionic are
short
GANGLIA Paravertebral ganglia and
prevertebral ganglia
Terminal external and
intramural

5. Sympathetic
CNS ganglion
short preganglionic
neuron
long postganglionic
neuron
target
Parasympathetic
CNS ganglion
long preganglionic
neuron
target
short postganglionic
neuron
Relative Lengths of Neurons

6. The particulars of the vegetative nervous system are
following:
• Smaller caliber of the nervous fibres
• Lower velocity of stimulation conduction
• Absence of myelin coat in many nervous conductor
• The focal (hidus) disposition of the vegetal nuclei in the
central nervous system
• Accumulation of the effector cell bodies ganglions as a
components of the vegetative plexuses
• Two-neuron pathway

7. Location of Preganglionic Cell Bodies
Thoracolumbar
T1 – L2/L3 levels
of the spinal cord
Craniosacral
Brain: CN III, VII, IX, X
Spinal cord: S2 – S4
Sympathetic Parasympathetic

8. The Autonomic Nervous System
The Parasympathetic Division
Figure 8-35

9. The autonomic (vegetative) ganglion is a collection of cell bodies of
the second neurons of the vegetative nervous system outside the
CNS. The first of the two motor neurons in any autonomic motor
pathway is called a preganglionic neuron. Its cell body is in the brain
or spinal cord, and its axon exits the CNS as part of a cranial or
spinal nerve. The axon of a preganglionic neuron is a small-diameter,
myelinated type fiber that extends to an autonomic ganglion. There it
synapses with a postganglionic neuron, the second neuron in the
autonomic motor pathway. Notice that the postganglionic neuron lies
entirely outside the CNS. Its cell body and dendrites are located in
an autonomic ganglion, where it forms synapses with one or more
preganglionic axons. The axon of a postganglionic neuron is a small-
diameter, unmyelinated type fibers that terminates in a visceral
effector. Thus, preganglionic neurons convey nerve impulses from
the CNS to autonomic ganglia, and postganglionic neurons relay
impulses from autonomic ganglia to visceral effectors.

10. 1) parasympathetic fibres, which divided into preganglionic
and postganglionic. Preganglionic parasympathetic fibres form
by the axons of the parasympathetic nuclei of the cranial nerves.
They end as synapses with cells of the parasympathetic ganglia.
Postganglionic axons extending from ganglion synapse and
pass to smooth muscles and glands.
2) sensory fibres, which pass transit through the ganglion;
3) postganglionic sympathetic fibers, which pass transit
through the ganglion
Each parasympathetic ganglion receives three types of
innervation:

11. 1) midbrain centre – accessory oculomotor nucleus (III CN);
2) Ponto -bulbar centre - the superior salivary nucleus (VII CN);
the inferior salivary nucleus (IX CN);
dorsal nucleus of the vagus nerve (X CN);
Centres of the parasympathetic vegetative
nervous system:

12. It lies lateral to each optic nerve near the posterior aspect of the orbit.
Parasympathetic fibres: preganglionic axons pass with the oculomotor nerve to the
ciliary ganglia. Postganglionic axons from the ganglia innervate smooth muscle fibres
in the eyeball – the ciliary muscle and the sphincter pupillae.
Sympathetic postganglionic fibers: from the cavernosus plexus (dilatator pupillae
muscle).
Sensory fibres: ganglionic branch or long branch from the nasociliary nerve (I branch
of the trigeminal nerve).
Short ciliary nerves exit from the ciliary ganglion.
The ciliary ganglion
)

14. It is located laterally to the sphenopalatine
foramen.
Parasympathetic fibres: it receives
preganglionic axons from the greater
petrosal nerve (facial nerve) and sends
postganglionic axons to the nasal mucosa,
palate, pharynx, and lacrimal glands.
Sympathetic postganglionic fibres: deep
petrosal nerve.
In the pterygoid canal the greater petrosal
nerve (preganglionic parasympathetic) and
the deep petrosal nerve (postganglionic
sympathetic) together form the nerve of the
pterygoid canal, which comes out into the
pterygopalatine fossa and proceeds to the
pterygopalatine ganglion.
Sensory fibres: pterygopalatine nerve or
ganglionic branch (II branch of the trigeminal
nerve).
The pterygopalatine ganglion

16. They are found near the ducts of the submandibular salivary glands.
Parasympathetic fibres: they receive preganglionic axons from the tympanic
cord (the facial nerve) and send postganglionic axons to the submandibular and
sublingual salivary glands.
Sympathetic postganglionic fibres: the facial plexus (the external carotid
plexus)
Sensory fibres: submandibular or sublingual branches of the lingual nerve (III
branch of the trigeminal nerve)
The submandibular and sublingual ganglia

17. The otic ganglion is situated just inferior to each oval foramen.
Parasympathetic fibres: it receives preganglionic axons from the
lesser petrosal nerve of the tympanic nerve (the glossopharyngeal
nerve) and sends postganglionic axons to the parotid salivary glands.
Sympathetic postganglionic fibres: the middle meningeal plexus
(the external carotid plexus)
Sensory fibres: the auriculotemporal nerve (III branch of the
trigeminal nerve)
Otic ganglion

18. Sacral part of Parasympathetic Nervous System
The pelvic efferent cell bodies reside in the parasympathetic nuclei between
anterior and posterior grey columns of the spinal cord with respect to
segments S II through segment SIV.
Pelvic splanchnic nerves – arise from the anterior rami of sacral spinal
nerves S II – S IV .

19. Parasympathetic
Pathways
Moore’s COA6 2010
Cranial outflow
• CN III, VII, IX, X
• Four ganglia in head
• Vagus nerve (CN X) is major
preganglionic parasymp.
supply to thorax & abdomen
• Synapse in ganglia within
wall of the target organs (e.g.,
enteric plexus of GI tract)
Sacral outflow
• S2–S4 via pelvic splanchnics
• Hindgut, pelvic viscera, and
external genitalia
Clinical Relevance
» Surgery for colorectal cancer
puts pelvic splanchnics at risk
» Damage causes bladder &
sexual dysfunction

20. Figure 20-2.
Sympathetic and Parasympathetic Effects on Body Tissues
The fear has big eyes

21. Parasympathetic Responses