Nervous system by Dr Chaman Lal (CK)

Federal Institute of Health Sciences Multan

By: Chaman Lal
B.S.PT, DPT, Dip. in sports Injuries, MPPS(PAK),
PG in Clinical Electroneurophysiology (AKUH),
Registered.EEGT (USA),
Member of AANEM & ASET (USA).

Study Outlines
 Introduction to Nervous System
 Classification of Nervous System
 Cells Types of Nervous System
 Functions of different types of cells
 Blood Brain Barriers
 Neuromuscular Junction (Synapse) & Its

Types
 Reflex Arc & its components
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Nervous System By: CK (FIHS)

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Introduction to Nervous System
Nervous system is the chief controlling and
coordinating system of the body.
It controls & regulates all activities of the
body, weather voluntary or involuntary.
It adjusts the individuals to given
surroundings.
Its based on
-Sensitivity,
-Conductivity &
-Responsiveness
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Classification Of Nervous System
CONTROL SYSTEMS

There are two main control systems in your
body.
1. Nervous system – which has two main
sections,
1.
Central Nervous System (CNS)
1. 2.
Peripheral Nervous System (PNS)
2. Endocrine system – which is a system of
glands that release a number of signalling
chemicals known as hormones.
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Anatomical Divisions
of Nervous System
 Central Nervous System

(CNS)
 Brain
 Spinal Cord
 Peripheral Nervous
System (PNS)
 Spinal Nerves & Plexus
 Cranial Nerves
 Peripheral Nerves

MNEMONIC
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OLFACTORY
OPTIC
OCULOMOTOR
TROCHLEAR
TRIGEMINAL
ABDUCENS
FACIAL
VESTIBULOCOCHLEAR
GLOSSOPHARYNGEAL
VAGUS
ACCESSORY
HYPOGLOSSAL

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OH
ONCE
ONE
TAKES
THE
ANATOMY
FINAL
VERY
GOOD
VACATION
A-HEAD
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NERVOUS SYSTEM
CNS
Nervous
system
releases
electrical impulses that are
quick but the effects are short
lived and it involves the CNS
(either just spinal cord or both
spinal cord and brain) messages
are carried by neurons

PNS
ANS

SNS

Parasympathetic Sympathetic
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Classification of NS…cont’d

 Central or CNS that is made up

of the spinal cord and brain and
functions to coordinate all
actions of the body
 Peripheral or PNS that is made

up of the bodies nerves and
functions to connect the CNS to
the rest of the body through
neurones. do require a fast
response (rest and digest response)

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Functional Divisions Of Nervous System
 Afferent

 Efferent
 Somatic
 Autonomic




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Sympathetic
Parasympathetic

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Functional Divisions Of Nervous System
Central Nervous System
Brain
Spinal Cord

Sensor Division
(afferent)

Peripheral Nervous System
Cranial Nerves
Spinal Nerves

Motor Division
(efferent)

Autonomic Nervous System
(involuntary)

Somatic Nervous System
(voluntary)

Classification of NS…cont’d

PNS is further divided into:
 Somatic or SNS which is associated with the

voluntary control of body movements and is made up
of all neurones, sense organs, skin, skeletal muscles
 Autonomic or ANS which is associated with the
involuntary control of body movements such as
reflex and controls such things as heart rate, body
temperature, digestion etc.

 The ANS is further divided into :
 Parasympathetic nervous system
works in actions that do not require a fast
response e.g rest & Digest etc
 Sympathetic nervous system works in
actions that do require fast response. e.g
Fight & Freight etc
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Name

Description

Important named parts
Telencephalon (Cerebral Cortex &
cerebrum).

Forebrain
Prosencephalon

Largest part of the
brain.

Basal Ganglia

Diencephalon (thalamus,
hypothalamus, pineal body)

Midbrain
Mesencephalon
(brain stem)

1.5 cm in length.

cerebral peduncles.
Pons.

Hindbrain
Rhombencephalon
(brain stem)
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Quadrigeminal bodies

Medulla oblongata.
Cerebellum.

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Parts of the nervous system
For example;
If you smell something burning…
 Your nose (receptor) detects the stimulus
(smell)
 Nerve fibres send the message to the brain
 Your brain then sends a message to move
your body away or to put out the fire!

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RECEPTORS
 Receptors are sensors on the body that detect stimuli
 They

convert stimuli into
(messages) called impulses.

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electrical

signals

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EFFECTORS
An effector is any part of the body that produces
the response.
Here are some examples of effectors:
 a muscle contracting to move the arm
 a muscle squeezing saliva from the salivary gland
 a gland releasing a hormone into the blood

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Cell Types of Nervous System
 Nervous System is composed of two distinct

types of cells.
a. Excitable Cells:
These are the nerve cells or neurons.
b. Non-excitable Cells:These cells constitute neurologlia and
ependyma in the CNS, & schwann cells in
the PNS.
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a. NERVE FIBRES
 Nerve fibres are bundles of nerve cells

(neurons) that pass on electrical signals
(impulses) to the brain.
 From the brain, nerve fibres send impulses
to effectors (muscles).

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Neuron: It has a cell body or soma or

PERIKARYON, with nucleus in center and nissl
granules in its cytoplasm.
 It has cell processes called “nenrites” which are
of two types. Many short afferent
processes, which are freely branching and
varicose are called “Dendrites”.
 A single long efferent process, which may give
off occasional branches (collateral) and is of
uniform diameter, is called “Axon”.
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Neuron: The terminal branches of the axon are called

axon
terminals,
axon
knobs,
axon
telodendria, or axon button.
 The cell bodies (somata) of the neurons
form grey matter and nuclei in the CNS, and
ganglia in the PNS.
 The cell processes (axons) form tracts ion
the CNS, & nerves in the PNS.
 Schwann cells form sheaths for axons of
PNS while oligodendrocytes form sheath in
CNS.
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Neurons and neuroglial cells

 Axon in peripheral nervous system with myelin sheath

formed by Schwann cells
 Provides for insulation and allows for saltatory
propagation of action potentials
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Saltatory conduction and role of Schwann cells

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TYPES OF NEURONS
 Neurons can be classified in several ways.
 According to their,
 1.Number of

their processes (Neurites)
 2.Length of their axon
 3.Function
 According to Number of Processes:-

 A.Unipolar  Mesencephalic nucleus
 B. Psudo-unipolar  Sensory ganglia
 C. Bipolar  Spiral & vestibular ganglia
 D. Multipolar  The most common types
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2. According to Length of Neuron: Golgi Type-I Neuron:-

With a long axon &
 Golgi Type-II Neuron:also called microneurons, with a
short or no axon (anaxonic neuron).

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3. According to Functions of neurons:There are three types of neurons according to their
function;
1. Sensory neuron – carries impulses from the receptors
to the spinal cord.
2. Relay Neuron – carries impulses to and from the
spinal cord and the brain
3. Motor Neuron – carries impulses from the brain to the
effector.

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Types of Neurons--structural classes

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Important Points:The average human brain has about 100 billion

neurons (or nerve cells) and an equal or slightly
greater number of neuroglia (or glial cells)
which serve to support and protect the neurons.
Each neuron may be connected to up to 10,000
other neurons, passing signals to each other via as
many
as
1,000
trillion
synaptic
connections, equivalent by some estimates to a
computer with a 1 trillion bit per second
processor.
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b.Neuroglial cells in CNS
 The non-excitable cells of the NS form a major

component of nervous tissues. These include :

 1.

Neurologlial Cells: found in the parenchyma of
brain and spinal cord.
 2. Ependymal Cell: Lining the internal cavities.
 3. Capsular or Satellite Cells: Surrounding neurons
of the sensory and autonomic ganglia.
 4. Schwann Cells: forming sheaths for axons of
peripheral nerves.
 5. Several types of supporting cells: ensheathing
the motor and sensory nerves terminals and
supporting the sensory epithelia.
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b.Neuroglial cells in CNS…cont’d

The Neuroglial cells found in the parenchyma of brain
and spinal cord are broadly classified as;


A.
Macroglia:Theses are;
a.
Astrocytes
b.
Oligodendrocytes &
c.
Glioblasts


B.

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Microglia


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Nervous Tissue: Support Cells (Neuroglia or Glia)
A. Astrocytes:Abundant, star-shaped cells. These are of two
types:

1.Protoplasmic
Astrocytes:
Have
thick
and
symmetrical processes and found in grey matter.
2.Fibrous Astrocytes: Have thin and asymmetrical
processes and found in white matter.
The processes of astrocytes often end in plate-like
expansions on the blood vessels, ependyma , & pial
surface of the CNS.

These form barrier between capillaries & neurons.
Control the chemical environment of the brain (CNS).
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Nervous Tissue: Support Cells….cont’d

B.

Oligodendrocytes(CNS):
These have fever cell processes.
These are of two types;
1. Intrafasicular Cells:- These cells are found
in the myelinated tracts,
2.Perineuronal Cells:- These are present on
the surface of the somata of neurons.
These produce myelin sheath around nerve fibers
in the central nervous system.


 C.

Glioblasts:These are stem cells which can be differentiate into macroglial
cells. They are particularly numerous beneath the ependyma.
B. Microglia:
 These are smallest of the glial cells. These have flattened cell
body with a few short, fine processes.
 Monitor health of neurons and transform into immune
macrophages (normal immune cells have no access to CNS).
 These are Spider-like and are phagocytic in nature.
 These dispose of debris
 Microglial cells are possibly derived from the circulating
monocytes which migrate cells are possibly derived from
the circulating monocytes which migrate into the CNS
during the late foetal and early postnatal life.
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2.
Ependymal cells (CNS):
 These Line the cavities of the brain and spinal cord
 Cilia beat to move or circulate cerebrospinal fluid
(CSF).
 These form barrier between CFS and tissue fluid.
3.
Satellite cells:

These surround the neurons of sensory &
autonomic ganglia.
These protect neuron cell bodies.
4.

Schwann cells (PNS):
Form myelin sheath in the peripheral nervous
system.

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Neuroglial cells in CNS

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Functions of Glial & Ependymal Cells
1) These provide mechanical support to neurons.
2) As non-conducting nature these act as insulators
between the neurons & prevent neuronal impulses
from spreading in unwanted directions.
3) By phagocytosis they help to engulf the foreign
material and removal of debris.
4) Help to repair the damaged area of nervous tissue. By
proliferation (gliosis) they form glial scar tissue, and
fill the gaps left by degenerated neurons.
5) Glial cells can take up and store neurotransmitters
released by the neighboring synapses. These can
either be metabolized or released again from the glial
cells.
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Functions of Glial & Ependymal Cells….cont’d

6. They help in neuronal functions by maintaining

7.
8.
9.
10.

a suitable metabolic and ionic environment for
the neuron.
Oligodendrocytes myelinate tracts in CNS and
schwann cell myelinate the nerves in PNS.
Ependymal cells are concerned with exchanges
of materials between brain and CSF.
The role of glial cells in the nutrition of nerve
cells is claimed since long but is not confirmed.
These act as blood brain barrier.

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Blood Brain Barrier
• Composed of specialized endothelial cells which form
tight intercellular junctions which selectively pass the
substances across the brain tissue.
Formation of junctions is dependent on:
Cytokines or factors derived from
astrocytes
The nature of the extracellular matrix
• These have few pinocytotic vesicles.
• There are greater number of mitochondria per unit
cell present than occur in other endothelial cells.
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Blood Brain Barrier……cont’d

 The possible Structures constituting the blood brain
barrier are:
 A). Capillary endothelium without fenestrations
 B). Basement membrane of the endothelium
 C). The end feet of astrocytes covering the capillary
walls.

The barrier permits a selective passage of
blood contents to the nervous tissue, and thus the
toxic and harmful substances are ordinarily
prevented from reaching the brain.
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Reflex Arc
 A reflex arc is the basic functional unit of the

system, which can perform an integrated neural activity. In
its simplest form (monosynaptic reflex arc). It is made up
of;
 1).
A Receptor e.g., skin
 2).
A sensory or afferent neuron
 3).
A interneuron (inter communicating neuron)
 4).
A motor or efferent neuron &
 5).
An effector, e.g. Muscle
The complex forms of reflex are polysynaptic due to
addition of one or more interneuron in between the
afferent and efferent neurons.
An involuntary motor response of the body called a reflex
action.
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The Reflex Arc

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The Reflex Arc
Reflex – rapid, predictable, and
involuntary responses to stimuli
Reflex arc – direct route from a sensory
neuron, to an interneuron, to an effector

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Simple Reflex Arc

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Synapse
 It is the functional junction gap along with the impulses

are conducted in different directions, each junction
between the neurons is called a “synapse”.
 Impulse is transmitted across a synapse by specific
neurotransmitters like acetylcholine, catecholamines
(noradrenalin
&
dopamine), serotonin, histamine, glycine, GABA, and
certain polypeptides.
 Types of Synapses are:
1. Axo-dendritic,
2. Somato-somatic
3. Somato-dendritic
4. Serial in Nature
Functionally, a synapse may be inhibitory or excitatory.
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Synapse

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Neuro-muscular junction
is synapse between motor
unit and muscle cell
(motor unit).


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Classification of Peripheral Nerve Fibers
 A . According to their Function: 1.Somatic efferent:- to supply striated muscles of somatic origin.
 2.General Visceral efferent:- to supply smooth muscles and








glands.
3.Special Visceral efferent (branchial efferent):- to supply
striated muscles of branchial origin.
4.General Somatic afferent:_ to carry exteroceptive impulses
from the skin, and proprioceptive impulses from the
muscles, tendons and joints.
5.General Visceral afferent:- to carry visceroceptive impulses
(like pain) from the viscera.
6.Special Visceral Afferent:- to carry the sensation of taste, &
7.Special somatic afferent: to carry the sensations of
smell, vision, hearing and equilibrium.
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Classification of Peripheral Nerve Fibers
 B. According to their size & speed of conduction:-

1.

Group-A fibers:- (Thickest & fastest)
-These are myelinated neurons having diameter of 1.522 microns.
- Their conduction speed is 4-120 meters per second.
- e.g. skeletomotor fibers (alpha A), fusimotor fibers
(beta A & gamma A), and afferent fibers to
skin, muscles & tendons.
2.
Group-B fibers:- (Medium size and speed)
-These myelinated and have diameter of 1.5-3 microns.
-Their conduction speed is 3-15 meters per second.
-e.g., Preganglionic autonomic efferents.
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Classification of Peripheral Nerve Fibers….cont’d

3.

Group-C fibers:- (Thinnest and slowest).

- These are non-myelinated have the diameter of 0.1-2
microns.
-Their conduction speed is 0.5-4 meters per second.
-e.g., Postganglionic autonomic efferents, and afferent
fibers to skin, muscles and viscera.
-The same efferents with a conduction speed and
myelination similar to B fibers are called delta-A fibers.
-Thus the fiber diameter is directly proportional to
conduction velocity; the velocity (in meters per second) is
approximately six times the diameters (in microns).

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“Horns” In The Spinal Cord
 In the spinal cord the gray matter is present inside and

white matter is towards outside while in brain this
distribution is vice versa.
 On cross section of the spinal cord gray matter in spinal
cord presents butterfly like structure form which some
projections like “Horns” are seen termed as:

Ventral/Anterior Horn→ {Ventral/Anterior/Motor
Root Centre}
Lateral Horn →{Preganglionic Sympathetic Neurons;
its present only in T1-L2}

Dorsal/Posterior Horn→{Dorsal/Posterior/Sensory
Root Centre}
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Terms To define….cont’d

 Root
• Ventral/Anterior/Motor/Efferent Root:
It arises from Ventral or Anterior horn of
the Spinal Cord and carries only motor fibers.
• Dorsal/Posterior/Sensory/Afferent Root:
It arises from Dorsal or Posterior horn of
the Spinal Cord and carries only sensory fibers.

Spinal Nerve:
• The dorsal and ventral roots, arising from each spinal cord

segment, fuse within the intervertebral foramen to form a
mixed spinal nerve.

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Terms To define….cont’d

Collection of the nerve cell bodies is called
“Ganglion” e.g., Dorsal Root Ganglion “DRG”, sympathetic
paravertebral ganglion.

 Ganglion:

 Ramus (Pl. rami)

The spinal nerve when exits from the vertebrae it divides
into two branches termed as;
1. Ventral/Anterior Primary Ramus
2. Dorsal/Posterior Primary Ramus
• Ventral/Anterior Ramus:

It is the ventral or anterior division of the
spinal nerve out side the vertebrae. It supplies to the
skin, muscles on anterior body & viscera etc.
• Dorsal/Posterior Ramus:

It is the dorsal or posterior division of the
spinal nerve out side the vertebrae. It supplies to the skin
& muscles of the back.
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Spinal Nerves
 31 pairs spinal nerves:

8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1
coccygeal nerve.
 Formation: each spinal nerve is formed by union of
anterior and posterior roots at intervertebral foramen
 The anterior root － contains motor fibers for
skeletal muscles. Those from T1 to L2 contain
sympathetic fibers; S2 to S4 also contain
parasympathetic fibers.
 The posterior root－contains sensory fibers whose
cell bodies are in the spinal ganglion.
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Spinal Nervers

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Nerve Structure: The whole nerve trunk is
ensheathed by PINEURIUM.

 Each
fasciculus
by
PERINEURIUM.
 Each nerve fiber by a delicate
ENDONEURIUM.
 The toughness of a nerve is due

to its fibrous sheaths, otherwise
the nerve tissue itself is very
delicate and friable.

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Nerve Fibers
 Large axons are covered by a myelin sheath and termed
myelinated or medullated fibers. (white matter as in
CNS).
 Thinner axons of less than one micron diameter do not
have the myelin sheath are therefore termed as nonmyelinated or non-medullated fibers (grey fibers).

 However, all the fibers whether myelinated or nonmyelinated have neurolemmal sheath, which is
uniformly absent in the tracts. In peripheral
nerves, both the myelin and neurolemmal sheaths are
derived from schwann cells.
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Myelinated Fibers
 Myelinated fibers form the bulk of the somatic nerves.
 Structurally, they are made up of following parts from

within outwards.
 1. Axis Cylinder forms the central core of the fiber. It
consists of axoplasm covered by axolemma.
 2. Myelin
sheath,
derived
from
Schwann
cells, surrounds the axis cylinder. It is made up of
alternate concentric layers of lipids and proteins formed
by spiralization of the mesxaon: the lipids include
cholesterol, gylcolipids and phospholipids.
 The myelin sheath is interrupted at regular intervals
called the node of Ranvier where adjacent schwann cell
meet.
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Myelinated Fibers cont’d. . .

 Thicker axons posses a thicker coat of myelin and
longer internodes.
 Each internode is myelinated by one schwann cell.

 Myelin can also show localized areas of incomplete
fusion of the Schwann cell membrane. Oblique
clefts in the myelin, called incisures of Schmidt
Lanterman, provide conduction channels for
metabolites into the depth of myelin and to the
subjacent axon. These areas (or incisures)may be
found trapped between membranes.
 Myelin sheath acts as an insulator for the nerve
fibers.
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3. Neurolemmal Sheath (Sheath of Schwann)

surrounds the myelin sheath. It presents
the plasma membrane. (basal lamina) of
the Schwann cell. Beneath the membrane
there lies a thin layer of cytoplasm with the
nucleus of the schwann cell. The sheaths of
two cells interdigitate at the node of ranvier.
4. Endoneurium, is a delicate connective
tissue sheath which surrounds the
neurolemmal sheath.
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 mesaxon /mes·ax·on/ (mes-ak´son) a pair of parallel membranes

marking the line of edge-to-edge contact of Schwann cells
encircling an axon.

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 Neurolemmal sheath is necessary for regeneration of a

damaged nerve.
 Tracts do not regenerate because absence of
neuroloemma.
 Endoneurium is a delicate connective tissue sheath which
surrounds the neurolemmal sheath.

Non-myelinated fibers
 Consist of smaller axons of the CNS, in addition to

peripheral postganglionic autonomic fibers, several types
of fine sensory fibers (C fibers of skin, muscles and
viscera), olfactory nerves etc.
 Structurally, a non-myelinated “fiber” consists of groups
of axons (0.12-2 microns diameter) that have invaginated
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Non-myelinated fibers…cont’d

 Separately a single schwann cell (in series) without any

spiraling of the mesaxon.
 The endoneurium , instead of ensheathing individual
axons, surrounds all the neurolemmal sheath by virtue of
which of the non-myelinated fibers, like the myelinated
fibers, can regenerate after damage.

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Degeneration & Regeneration of Neurons
 If nerve (axon) is injured or cut a series of degenerative and

than regenerative changes follow.
 Degeneration is of two type;
1.
Retrograde degeneration:
Degenerative changes in the neurons that occur in proximal
part to injury.
2. Antegrade degeneration:
Degenerative changes in the distal part to site of injury.
a. The cell bodies undergo chromatolysis with in 48 hours of
injury. The cell becomes swollen and rounded, nucleus is
pushed to the periphery, and the nissl granules disintegrate
and disappear.
b. The proximal part of the axon survives if the mother cells do
not die. Only a small segment near the cut end degenerates in
a way similar to the distal part.
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Degeneration & Regeneration of Neurons….cont’d

c.

A the site of injury, the schwann cells proliferate
more actively in the distal part than in the proximal, in
an attempt to fill the gap. Gaps up to 3cm may be
bridged in this way. Bridging can be facilitated by
stitching the two parts. However, in wider gaps nerve
grafts may be tried.
d.
The distal part of the axons undergoes Wallerian
(antegrade) degeneration within a few days of injury. The
axis cylinder becomes fragmented and the myelin sheath
breaks up into fat droplets. The schwann cell
multiply, which on one hand act as macrophages to
remove the debris of degenerated axon and myelin, and
on the other hand form a large series of membranous
(neurolemmal) tubes which play a vital role in
regeneration of the nerve fibers. The nucleated cellular
cords in the distal part are called bands of Bungner.
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Different degrees of Nerve Injury

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Spinal Nerve….cont’d

 Dermatome:-

An area of skin supplied by a single segment spinal nerve
is called dermatome.
 Myotome:Group of Muscle fibers supplied by single segment of
spinal nerve is called myotome.
Nerve Plexuses for Limbs:A network of spinal nerves formed by ventral rami is
known as nerve plexuses. Plexus formation is a physiological
or functional adaptation, and is perhaps the result of the
following special features in the limbs.
1. Overlapping of dermatomes,
2. Overlapping of myotomes,
3. Composite nature of muscles,
4. Possible migration of muscle from the trunk to the limbs &
5. Linkage of the opposite groups of muscles in the spinal cord
for reciprocal innervation.
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Blood & Nerve Supply of Peripheral Nerves
 The peripheral nerves are supplied by vessels, called

vasa
nervorum,
which
form
longitudinal
anastomoses on the surface of the nerves.
 The nerves distributed to the sheaths of the nerve

trunks are called nervi-nervorum.
Anastomosis:A precapillary of postcapillary communication
between neighboring vessels is called as anastomosis.
- Circulation through anastomosis is called Collateral
Circulation.
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Parasympathetic Nervous System (PNS)
 Parasympathetic Nervous System (PNS)
 The hypothalamus is the center of the parasympathetic

nervous system. It operates through various
interconnecting systems and organs. This system is
responsible in the “thinking” phase in stressful
situations and is called the “Rest and Digest” phase
because your body goes back to its normal responses.
 It is also known as ‘craniosacral’ outflow because it
arises from the brain (mixed with 3rd, 7th, 9th & 10th
cranial nerves) and a S 2-4 segments of the spinal cord.
Thus it has a cranial and a sacral part.
 Parasympathetic nerve endings are cholinergic in
natures.
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Sympathetic Nervous System (SNS)
 This type of the autonomic nervous system is

responsible in the distribution of essential nutrients
and oxygen to the various parts of the body. This ANS
is responsible for “Flight or Fight.” The body has to
respond immediately because of the urgency of some
situations.
 It is also known as ‘thoracolumbar’ outflow because it
arises from T1-L2 segments of the spinal cord.
 The medullated Preganglionic fibers arise from the
lateral column of the spinal cord, emerge through the
ventral rami where the white rami are connected to the
ganglia of the sympathetic chain.
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Sympathetic Nervous System (SNS). . . Cont’d

 Sympathetic nerve endings are adrenergic in nature,

meaning thereby that noradrenalin is produced for
neurotransmission. The only exception to this general rule
are the cholinergic sympathetic nerves supplying the sweat
glands and skeletal muscle vessels for vasodilatation.
 Functionally,
sympathetic
nerves
are
vasomotor
(vasoconstrictor), sudomotor (scretomotor to sweat
glands), and pilomotor (contract the arrector pili and cause
erection of hair) in the limbs and body wall.
 In addition, sympathetic activity causes dilation of pupil,
pale face, dry mouth, tachycardia, rise in blood pressure,
inhibition of hollow viscera, and closure of the perinal
sphincters.
 The blood supply to the sk.m/s, heart & brain is increased.
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Characteristics

Parasympathetic

Sympathetic

Craniosacral outflow:
brainstem nuclei of
cranial nerves III, VII,
IX and X; spinal cord
segments S2-S4
Ganglia in
Location of ganglia
(intramural=
terminal) or close to
visceral organ served

Thoracolumbar
outflow: lateral horn
of gray matter of
spinal cord segments
T1-L2
Ganglia within a few
cm of CNS: alongside
vertebral column
(paravertebral
ganglia=chain) and
anterior to vertebral
column (prevertebral
ganglia)

Relative length of
Long preganglionic;
pre- and
short postganglionic
postganglionic fibers

Short preganglionic;
long postganglionic

Origin

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Characteristics Parasympathetic
Types of nerves
ending

Nature of Control

Metabolic effect
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Sympathetic

Cholinergic

Adrenergic

Discrete and
isolated, combat
long term
emergencies,

Wide Spread and
diffuse, combat
acute emergencies

Anabolic (Energy)
sparing

Catabolic (Energy
consuming)


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Nervous system by Dr Chaman Lal (CK)

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