Vegetative nervous system. Anatomy

1. Ivano-Frankivsk National Medical University
The Department of Human anatomy
Vegetative nervous
system
Prepared by PhDPrepared by PhD
Tetyana Knyazevych - ChornaTetyana Knyazevych - Chorna

2. Plan
 Introduction to the autonomic nervous system.
 Division of ANC.
 Central Control of the ANS.
 Function of the the parasympathetic nervous
system.
 Function of the sympathetic nervous system.

3.  The autonomic nervous system (ANS
or involuntary nervous system) is the part
of the peripheral nervous system that
controls visceral functions.
 The ANS affects heart
rate, digestion, respiratory
rate, salivation, perspiration, diameter of the
pupils, urination, and sexual arousal.

4.  It is classically divided into two
subsystems:
 the parasympathetic nervous system
(PSNS)
 sympathetic nervous system (SNS)

5. The Autonomic Nervous System and Visceral
Sensory Neurons
Figure 15.1

6. Central Control of the ANS
 The medulla oblongata and pons (the
vascolomotor, the respiratory, the vomiting, the
deglutetion centres)
 The cerebellum (the skin trophics, wound
healing)
 The hypothalamus (metabolism, body
temperature, sexuality and activities of the
endocrine glands)
 The telencephalon (blood pressure, salivation,
lacrimation)
 The cerebral cortex

7. Sympathetic
 Helps the body cope with external stimuli and functions
during stress (triggers the flight or fight response)
 Diverts blood flow away from the gastro-intestinal (GI) tract
and skin via vasoconstriction.
 Blood flow to skeletal muscles and the lungs is enhanced (by
as much as 1200% in the case of skeletal muscles).
 Dilates bronchioles of the lung, which allows for greater
alveolar oxygen exchange.
 Increases heart rate and the contractility of cardiac cells (
myocytes), thereby providing a mechanism for the enhanced
blood flow to skeletal muscles.
 Dilates pupils and relaxes the ciliary muscle to the lens,
allowing more light to enter the eye and far vision.
 Provides vasodilation for the coronary vessels of the heart.
 Constricts all the intestinal sphincters and the urinary
sphincter.
 Inhibits peristalsis.
 Stimulates orgasm.

8. Parasympathetic
 Works to save energy, aids in digestion, and supports restorative, resting
body functions.
 Dilates blood vessels leading to the GI tract, increasing blood
flow.
 The parasympathetic nervous system can also constrict the
bronchiolar diameter when the need for oxygen has diminished.
 Dedicated cardiac branches of the Vagus and thoracic
Spinal Accessory nerves impart Parasympathetic control of the
Heart orMyocardium.
 During accommodation, the parasympathetic nervous system
causes constriction of the pupil and contraction of the ciliary
muscle to the lens, allowing for closer vision.
 The parasympathetic nervous system stimulates salivary gland
secretion, and accelerates peristalsis, so, in keeping with the rest
and digest functions, appropriate PNS activity mediates digestion
of food and indirectly, the absorption of nutrients.
 Is also involved in erection of genitals, via the
pelvic splanchnic nerves 2–4.
 Stimulates sexual arousal.

9.  Autonomic nervous system
Chain of two motor neurons
 Preganglionic neuron
 Postganglionic neuron
Conduction is slower due to thinly or
unmyelinated axons
Pre-ganglionic
Ganglion
Post-ganglionic

10. Autonomic and Somatic Motor
Systems
Figure 15.2

11. Figure 15.3
Anatomical Differences in Sympathetic
and Parasympathetic Divisions
 Issue from
different regions of
the CNS
Sympathetic – also
called the
thoracolumbar
division
Parasympathetic –
also called the
craniosacral
division

12. Anatomical Differences in Sympathetic
and Parasympathetic Divisions
 Length of postganglionic fibers
Sympathetic – long postganglionic fibers
Parasympathetic – short postganglionic fibers
 Branching of axons
Sympathetic axons – highly branched
 Influences many organs
Parasympathetic axons – few branches
 Localized effect

13. Neurotransmitters of Autonomic
Nervous System
 Neurotransmitter released by
preganglionic axons
Acetylcholine for both branches (cholinergic)
 Neurotransmitter released by
postganglionic axons
Sympathetic – most release norepinephrine
(adrenergic)
Parasympathetic – release acetylcholine

14. Anatomical Differences in Sympathetic
and Parasympathetic Divisions
Figure 15.4a

15. Anatomical Differences in Sympathetic
and Parasympathetic Divisions
Figure 15.4b

16. The
Parasympathetic
Division

17. Cranial part Sacral part
 Oculomotor nerve (III) –
accessory nucleus
 Facial nerve (VII) –
superior salivatory n.
 Glossopharyngeal nerve
(IX) - inferior salivatory n.
 Vagus nerve (X) – dorsal
nucleus
 Innervates organs of the
head, neck, thorax, and
abdomen
 Sacral parasymthetic
nuclei – between the
anterior and the
posterior grey
columns S2-S4
 Supplies remaining
abdominal and pelvic
organs

18. The Sympathetic Division
 Basic organization
Issues from C8 (Th1)-L2
Preganglionic fibers form the lateral gray horn
Supplies visceral organs and structures of
superficial body regions
Contains more ganglia than the
parasympathetic division

19. Sympathetic Trunk Ganglia
 Located on both sides of the vertebral
column
 Linked by short nerves into sympathetic
trunks
 Joined to ventral rami by white and gray
rami communicantes
 Fusion of ganglia  fewer ganglia than
spinal nerves

20. Sympathetic Trunk Ganglia
Figure 15.8

21. Prevertebral Ganglia
 Unpaired, not segmentally arranged
 Occur only in abdomen and pelvis
 Lie anterior to the vertebral column
 Main ganglia
Celiac, superior mesenteric, inferior
mesenteric, inferior hypogastric ganglia

22. Sympathetic Division of the
ANS
Figure 15.7

23. Sympathetic Pathways to Periphery
Figure 15.9

24. Sympathetic Pathways to the
Head
Figure 15.10

25. Sympathetic Pathways to Thoracic
Organs
Figure 15.11

26. Sympathetic Pathways to the Abdominal
Organs
Figure 15.12

27. Sympathetic Pathways to the Pelvic Organs
Figure 15.13

28. The Role of the Adrenal Medulla
in the Sympathetic Division
 Major organ of the sympathetic nervous
system
 Secretes great quantities epinephrine (a
little norepinephrine)
 Stimulated to secrete by preganglionic
sympathetic fibers

29. The Adrenal Medulla
Figure 15.14

30. Visceral Sensory Neurons
 General visceral sensory neurons monitor:
Stretch, temperature, chemical changes, and
irritation
 Cell bodies are located in the dorsal root
ganglia
 Visceral pain – perceived to be somatic in
origin
Referred pain

31. A Map of Referred Pain
Figure 15.15

32. Visceral Reflexes
 Visceral sensory and autonomic neurons
Participate in visceral reflex arcs
 Defecation reflex
 Micturition reflex

33. Visceral Reflex Arc
Figure 15.16

34. Disorders of the Autonomic Nervous System:
Raynaud’s Disease
 Raynaud’s disease – characterized by
constriction of blood vessels
Provoked by exposure to cold or by emotional
stress

35. Disorders of the Autonomic
Nervous System: Hypertension
 Hypertension – high blood pressure
Can result from overactive sympathetic
vasoconstriction

36. Disorders of the Autonomic Nervous System:
Mass Reflex Reaction
 Mass reflex reaction
Uncontrolled activation of autonomic and
somatic motor neurons
Affects quadriplegics and paraplegics

37. Disorders of the Autonomic Nervous System:
Achalasia of the Cardia
 Achalasia of the
cardia
Defect in the
autonomic
innervation of the
esophagus

39. The ciliary ganglion
 The ciliary ganglion is a parasympathetic ganglion
located in the posterior orbit. Preganglionic axons
from the Edinger-Westphal nucleus travel along the
oculomotor nerve and form synapses in ganglion.
The postganglionic axons run in the short ciliary
nerves and innervate two eye muscles:
 the sphincter pupillae constricts the pupil, a
movement known as Miosis. The opposite - dillatator
pupillae ,Mydriasis, is the dilation of the pupil.
 the ciliaris muscle contracts, releasing tension on
the Zonular Fibers, making the lens more convex,
also known as accommodation.
 Both of these muscles are involuntary – they are
controlled by the autonomic nervous system.

40.  The fibers that simply
pass through
ganglion:
 a
sympathetic root of ciliary ganglion
 a
sensory root of ciliary ganglion

41.  The pterygopalatine
ganglion (Synonym: meckel's ganglion)
is a parasympathetic ganglion found in
the pterygopalatine fossa.
 The pterygopalatine ganglion supplies the
lacrimal gland, paranasal sinuses, glands
of the mucosa of the nasal cavity and
pharynx, the gingiva, and the mucous
membrane and glands of the hard palate.
It communicates anteriorly with the
nasopalatine nerve.

42.  Its sensory root is derived from two sphenopalatine branches of
the maxillary nerve
 Its parasympathetic root is derived from the nervus intermedius
(a part of the facial nerve) through the greater petrosal nerve.
 The ganglion also consists of sympathetic efferent
(postganglionic) fibers from the carotid plexus - the
deep petrosal nerve. The deep petrosal nerve joins with the
greater petrosal nerve to form the nerve of the pterygoid canal
(Vidian), which enters the ganglion.

43.  The otic ganglion is a small, oval shaped,
flattened parasympathetic ganglion of a reddish-gray
color, located immediately below the foramen ovale
in the infratemporal fossa. It gives innervation to
the parotid gland for salivation.

44.  The sympathetic postganglionic fibers consists of a
filament from the plexus surrounding the
middle meningeal artery.
 Its sensory root is derived from the maxillary nerve
 Preganglionic parasympathetic fibers originate from
the glossopharyngeal nerve via the
lesser petrosal nerve.
 Postganglionic parasympathetic fibers travel with the
sympathetic fibers of the auriculotemporal nerve to
supply the parotid gland.

45.  The submandibular ganglion is responsible for
innervation of two salivary glands:
thesubmandibular gland and sublingual gland.
 It is situated above the deep portion of
the submandibular gland, on the hyoglossus muscle,
near the posterior border of the mylohyoid muscle.

46.  Sympathetic fibers from
the external carotid plexus, via
the facial nerve and its
branches.
 Its sensory root is derived from
the maxillary nerve
 Preganglionic parasympathetic
fibers via the chorda
tympani and lingual nerve,
which synapse at the origin of:
 Postganglionic parasympatheti
c fibers to the oral mucosa and
the submandibular and
sublingual salivary
glands.They are secretomotor
to these glands.