NEURO ANATOMY

2. 2

3.  The peripheral nervous system, or PNS, consists
of cranial nerves, spinal nerves and ganglia.
The PNS is subdivided into:
1. Autonomic nervous system
a) Sympathetic nervous system
b) Parasympathetic nervous system
2. Somatic nervous system
3

4.  ANS is a system that acts largely
unconsciously and regulates bodily
functions such as
• Heart rate
• Digestion
• Respiratory rate
• Pupillary response
• Urination and sexual arousal
4

5. Autonomic Nervous System
Classically divided into TWO subsystems
• Allow body to function under Stress
• Fight or flight
• Maintenance functions
• Rest and Digest
5

6. Autonomic Nervous System
In general nerve impulses from on division of ANS stimulate the Organ to increase
its activity (excitation), and another part inhibit the organs activity (inhibition).
Structurally , ANS includes:
i. Autonomic sensory neurons(afferent)
ii. Integrating centers in the CNS
iii. Autonomic motor neurons(efferent)
6

7. 7

8. 8

9. 1. Preganglionic neurons
2. Autonomic ganglia
3. Postganglionic neurons
9

10. • Its cell body located within gray matter of the CNS (brain and spinal cord)
• Its myelinated axon exits the CNS
• The preganglionic axon passes from the CNS in a spinal or a cranial nerve.
• The preganglionic axon terminates in a ganglion
• A ganglion is a collection of nerve cell bodies located in a specific site
within the body,(but outside the CNS)
10

11. • The cell body located in an Autonomic ganglion
• The axons of a postganglionic Unmylinated fibers
• The postganglionic axon passes from ganglion to the effector
• (cardiac muscle, smooth muscle, or gland) is either stimulated or inhibited.
11

12. • In the sympathetic division
(thoracolumbar division):
• the cell bodies in the lateral horns of gray
matter in the 12 thoracic segments (T1-T12)
and the first Two (L1-L2) lumbar segments of
spinal cord.
• Therefore, the sympathetic division is called
Thoracolumbar division.
12

13. The parasympathetic division (Craniosacral division)
• Cell bodies arise from the nuclei of cranial nerves in
the Brain stem III, VII, IX and X and the lateral gray
matter of Sacral segments (S2-S4) of spinal cord.
• Therefore, the parasympathetic division is called
Craniosacral division.
13

14. Autonomic Ganglia
Two major groups of autonomic ganglia:
(sympathetic division)
i. Sympathetic trunk ganglia (vertebral chain ganglia or
paravertebral ganglia)
ii. Prevertebral ganglia
(parasympathetic division)
i. Terminal ganglia (ciliary ganglia, pterygopalatine ganglion,
submandibular ganglion, otic ganglion)
14

15. (vertebral chain ganglia or paravertebral ganglia)
• Lies in a vertical row on either side of the vertebrae column.
• Extend from base to skull to the coccyx.
• Postganglionic axons from sympathetic trunk ganglia innervated organs above the diaphragm.
• In the neck (specific names)
• Superior cervical ganglion
• Middle cervical ganglion
• Inferior cervical ganglia
• Most sympathetic preganglionic axons are shorter than sympathetic postganglionic axons b/c
sympathetic trunk ganglia near the spinal cord.
15

16. 16

17. • Lie anterior to vertebral column and close to large abdominal arteries.
• Postganglionic axons from prevertebral ganglia innervated organs below to
diaphragm
• 5 major prevertebral ganglia:
1. Celiac ganglion
2. Superior mesenteric ganglion
3. Inferior mesenteric ganglion
4. Aorticorenal ganglion
5. Renal ganglion
17

18. Celiac ganglion  on either side of celiac trunk, just inferior to the diaphragm
Superior mesenteric ganglion  near the beginning of the superior mesenteric
artery in upper abdomen
Inferior mesenteric ganglion  near the inferior mesenteric artery in the middle
of the abdomen
Aorticorenal ganglion and renal ganglion  near the renal artery od each kidney
18

19. 19

20.  located very close to or
within the walls of a viscera organ to be innervated.
Terminal ganglia in the head are
• Ciliary ganglion
• Pterygopalatine ganglion
• Submandibular ganglion
• Otic ganglion
• Parasympathetic preganglionic axons are longer the
parasympathetic postganglionic axons b/c terminal ganglia
are close to the visceral organ.
20

21. • Once axons of sympathetic preganglionic neurons pass to sympathetic trunk ganglia, they may
connect with postganglionic neurons in one of the following ways:
1. An axons may synapse with postganglionic neurons in the ganglion it first reaches
2. An axons may ascend or descend to a higher or lower ganglion before synapsing with
postganglionic neurons.
3. Without synapsing, a axons continue through the sympathetic trunk ganglion to end at
prevertebral ganglion and synapse with postganglionic neurons there.
21

22. 22

23. • Axons of preganglionic neurons of
parasympathetic division pass to the
terminal ganglia near or within a visceral
effector
• In the ganglion, the presynaptic neuron
usually synapse with 4 or 5 postsynaptic
neurons, all of which supply a single visceral
effector
23

24.  Prepares the body in emergency demands (fight or flight response)
• Increasing heart beat
• Increase blood supply to cardiac muscle
• Raised peripheral resistance and blood pressure by constricting the small artery the skin.in
this way increase blood supply is available for highly active tissue, such as Skeletal muscle,
heart and brain.
• Constrict the blood vessel in secretory glands of digestive system
24

25. • Causes smooth muscle relaxation and therefore dilatation of the airways, especially bronchioles
• Allowing a greater amount of air to enter the lungs at each inspiration, and increase the
respiratory rate
• Liver increase conversion of glycogen to glucose
• Stomach and small intestine: smooth muscle contraction and secretion of digestive juices are
Inhabited (delaying digestion)
• Urethral and anal sphincter: muscle tone increase, inhibit Micturition and Defection
• Bladder wall relaxes
• Metabolic rate increase
25

26. • Dilating the pupil
• Increase sweat secretion, leading to increased heat loss from the body
• Constrict the peripheral blood vessel increasing blood supply available to active
organs, e.g heart and skeletal muscle
26

27. • PNS is energy conservation-restorative system.(rest and digest)
• Stimulating glandular secretion and gut movement necessary for food
to be digested and absorbed
• Salivation, lacrimation, urination, and defecation, all controlled by
parasympathetic nervous system
27

28. • Decrease heartbeat
• Constrict coronary artery reducing the blood supply to cardiac muscle
• Produces contraction of smooth muscle in airway walls causing their constriction,
e.g. bronchioles and bronchi
• Constricting the pupil
• Liver: conversion of glucose to glycogen and secretion of bile are increased
• Stomach and small intestine: motility and section are increased together with the rate of digestion and
absorption of food
• Pancreas: secretion of pancreatic juice and the hormone insulin are increase
• Urethral and anal sphincter: relaxation in urethral and anal sphincter, micturition and defecation occurs
28

29. Neurotransmitters are chemicals which transmit signals from a neuron to target
cell across the synapse
• the Hypothalamus regulates the balance of sympathetic versus parasympathetic
activity or tone
• Preganglionic neurons  Acetylcholine (Ach) as a neurotransmitter
• Most postganglionic neurons  noradrenaline(norepinephrine),
• except postganglionic neurons innervating sweat glands  acetylcholine.
29

30. • All pre and postganglionic neurons uses Acetylcholine (Ach) as its neurotransmitter
30

31. 31