The document provides a comprehensive overview of the nervous system, detailing its structure, functions, and various components including the central and peripheral nervous systems, brain parts, and spinal cord. It discusses the terminology related to gray and white matter, the divisions of the brain, and the meninges, along with their clinical significance. Additionally, it addresses the functionality of sensory and motor pathways, as well as the autonomic nervous system's roles.

1. OVERVIEW OF
NERVOUS SYSTEM
Presented By- Amrit Kour
Kriya Sharir Dept.
R.G.G.P.G Ayurvedic College &
Hospital ,Paprola

2. INDEX
Important Terminolgy
Overview of Brain & its Parts
Spinal cord & it’s cross – section
 Peripheral Nervous System & it’s further
division.
Meninges
Clinical importance of meninges.

3. Introduction
Nervous system is one of the control
systems of the body that control various
activities of the body, the other one
being the endocrine system .
Nervous system is quicker than the
endocrine system.

4. The basic structural &
functional unit of nervous
system is the individual
nerve cell, the Neuron.
Billions & Trillions of such
neurons constitute the
Nervous System.

5. Nervous System controls the activities of
the body
By generating and sending electrical signals
in the form of impulses to various organs
and regions of the body .
It coordinates these activities by receiving
input signals from different types of
receptors present throughout the body.

6. DIVISIONS OF NERVOUS SYSTEM
Primarily, nervous
system is divided into
two parts:
1. Central nervous
system
2. Peripheral nervous
system.

7. CENTRAL NERVOUS
SYSTEM
The part of the nervous
system which occupies the
central axis of the body is
called CNS.
CNS includes brain and spinal
cord.

8. Main Functions of CNS
Receive the Sensory information from
P.N.S
Process that Information & make the
decision
Send processed information output
through motor nerves.

9. IMPORTANT
TERMINOLOGY

10. CNS -
 Formed by neurons and supporting cells
called neuroglia.
Structures of brain and spinal cord are
arranged in two layers, namely
 Gray matter &
White matter.

11. Grey Matter
Group of cell bodies of neurons
within CNS.
1.Cortex – Grey matter on the
surface of CNS.
2. Nuclei – Grey matter
embedded in CNS
surrounded by white matter .
3.Ganglia – Grey matter outside
the CNS.

12. White Matter
Collection of Bundles of Axons
within C.N.S.
The fatty ‘myelin’ in myelinated nerve
fibers gives a white appearance to the
white matter.
1.Tracts – Bundles of Axons which
carry information Up & Down
(Ascending & Descending Tracts )

13. 2.Commissural Fibers –
Bundles of Axons which carry information from Right
cerebral hemisphere to left cerebral hemisphere and vise –
versa.
There are many commissural fibers in the brain
Largest Commissural Fiber – Corpus Callosum .

15. 3.Association Fibers -  These fibers
carry
information
from frontal lobe
to the occipital
lobe (anterior to
posterior lobe &
vice-versa)

16. Nerve -
Collection of
axons outside
the C.N.S
i.e.in the
Pheriphery .

17. Difference -
In brain, white matter is
placed in the inner part and
gray matter is placed in the
outer part.
 In spinal cord, white matter
is in the outer part and gray
matter is in the inner part.

18. THE BRAIN -
It’s weight is about 1.5kg in
adults.
It comprises all the structures
which are intracranial . i.e.
located within a hard bony skull.
PARTS OF BRAIN –
1. Forebrain
2. Mid-brain
3.Hind-Brain

19. The brain also contains 4
interconnected cavities , the cerebral
ventricles , that contain cerebrospinal
fluid (CSF).

20. 1. Forebrain (Prosencephalon)
Further divided
into
Telencephalon
&
Diencephalon .

21. A. TELENCEPHALON –
consists of two cerebral hemispheres and
their interconnections.
i.The hemispheres, although separated by
a longitudinal divison , are connected
to each other by bundles of nerve
fibers known as Commissures.
ii.Cortex of each Hemisphere is divided
into 4 lobes –
Frontal,Parietal ,Occipital &
Temporal .

22. iii.The cerebral cortex , an area of grey
matter, about 3mm thick , is highly
folded.
This increases the area available for
cortical neurons without increasing
appreciably the volume of the brain .
iv. The subcortical nuclei form other
areas of the grey matter that lie deep
within the cerebral hemispheres.
Predominant among them are the Basal

23. ii.Diencephalon-
Upper 2/3rd
comprises
of – Thalamus.
Lower 1/3rd
comprises of –
Hypothalamus
Connects with the
pituitary complex.

24. 2. Mid Brain
(Mesencephalon) -
 It is divided into two parts
by Aqueduct of Sylvius
( Duct which connects the
IIIrd Ventricle in the
midbrain , with the IVth
Ventricle in the pons &
Medulla ) into :-

25. It is Divided into two parts -
i] Ventral Part, called Cerebral Peduncle , chiefly of
white matter, uniting the Pons with the thalamic region
of the cerebrum.
 It comprises the – tegmentum, Substantia nigra & basis
peduncle.
 ii] Dorsal part, called tectum which constitutes two
elevations, superior and inferior colliculi.

26. 3.HindBrain (Rhombencephalon)
It comprises
Pons Metencephalon
Cerebellum
Medulla Oblongata –
Myelencephalon

27. BrainStem -
Midbrain, Pons & Medulla Oblongata
together constitute brainstem .
All cranial nerves are situated in the
brainstem.
i). In the Midbrain – III & IV nerves.
ii). In the Pons – V, VI, VII & VIII
nerves,
iii)). In the Medulla – IX , X , XI &
XII nerves.

29. The cerebellum is connected by three large
bundles of nerve fibres, the cerebellar
peduncles with the dorsal side of the brain
stem :
i). Via Superior Cerebellar Peduncle with
the midbrain,
ii) via Middle cerebellar Peduncle with the
pons ,&
iii) Via Inferior cerebellar Peduncle with

31. Running through the
core of the brain stem
and consisting largerly
of neuron cell bodies
(i.e.grey matter),
is the reticular
formation .


32. The Spinal Cord  Spinal cord is a long
(approx. 45- 50cm in
length) , narrow (about
2cm in diameter)
cylindrical structure.
 It lies outside the skull
 Beginning in the base at the
foramen magnum
 Terminate at the lower
border of 1st
lumbar
vertebra.

33. Below the 1st
lumbar
vertebra the spinal
cord contains the
lumbar & Sacral roots
in bands, known as
Cauda Equina (or
horse tail).

34. Cross – section of Spinal
Cord Anteriorly – fissure
Posteriorly – Sulcus
In the centre – central
canal
Inner side – grey matter
(Butterfly shaped or H
shaped).
Outer side – White matter.

35.  Inner side – grey matter (Butterfly shaped or H shaped).
 Horns are present –a. Anterior/ventral horn.
 b. Posterior/Dorsal horn.
 c. lateral horn.
 Around the central canal , grey commissure of spinal cord.

36.  The Dorsal or posterior horn –
receives the fibers of the
posterior roots which are purely
sensory in function .
 Their cell bodies are found in the
dorsal root ganglion .
 The Ventral or Anterior horn –
receive motor neurons from
ventral/anterior nerve root.
 These nerve fibers are purely
motor in function.

37. Major columns of Spinal Cord
1. Dorsal / Posterior Column
2. Anterolateral / ventrolateral
column

38. 1.Dorsal / Posterior Column
 It consists of Ascending Tracts or
Sensory nerve fibers.
 Most advanced system.
 Highly myelinated .
 Highly insulated – only limited
sensations are sensed.
 Carry sensations very fast.
 High – velocity system .
 Well developed advanced sensations
are present in this column.

39. Examples of Dorsal column sensations-
Very fine touch sensation,
Sense of positioning,
Pressure
Sense of Proprioreception – from locomotor
system.
Sense of two point Discrimination.

40. 2. Anterolateral / ventrolateral column
 It contain both Ascending &
Descending tracts.
 It is a Primitive – Tract System.
 It is poorly / Moderately
Myelinated.
 It is a slow Velocity System.
 All the primitive Sensations are
present.
 Variety of sensations are Present.

41.  Example ventrolateral column-
 Crude touch ,
Sensation of Itching,
Sexual sensation
Tickling sensation
Pain
Temp .

42. Peripheral Nervous System
The part of the Nervous System which lies
outside the CNS.
It consists of the nerves extending from the
brain & Spinal Cord out to all parts of the
body.

43. Peripheral Nervous System
 Sensory P.N.S.
a.General Senses b.Special Senses
i.Somatic Sensation ii.Visceral Sensations
 Motor P.N.S
 a.Voluntary NS
(Somatic NS)
 b.Involunatry NS
(Autonomic NS)

44. General Sensations –can be sensed through multiple parts of body. E.g Touch
 A.Somatic Sensations
 Sensations from superficial
areas of body such as Skin,
subcutaneous tissues.
 Senses such as Pain,Temp.
& Proprioreception – all the
sensations which are coming
from locomotor system,
especially sense of positioning .
 B.Visceral Sensations
 Senses from deeper part of
body i.e.from viscera to C.N.S.
 Examples –
 Dull pain
 Abdominal distension
 Spleenomegaly
 Hepatomegaly
 Blood pressure.

46. Motor P.N.S.
 a.Voluntary NS
 (Somatic NS)
 controlled by Skeletal muscles.
 Running .
 Hand shaking.
 b. Involunatry NS
 (Autonomic NS)
 Smooth muscles & Cardiac muscles.
 Glandular activities
 Sense of smell.
 Salivation etc.

47. a. Voluntary / Somatic NS –
made up of all the nerve fibers going from CNS to
the skeletal muscle cells.
It comprises spinal & cranial nerves.
 31 pairs of Spinal nerves
12 pairs of Cranial nerves.

48. Involunatry / Autonomic NS
The innervation of all tissues other than skeletal
muscle is by way of the ANS.
Also called Vegetative nervous system.
It has two divisons –
1. Sympathetic Division – consists of thoracic &
lumbar ganglia , also called Thoraco – Lumbar
division.
2. Parasympathetic Division – consists of cranial &
sacral ganglia , also called craniosacral division.

49. (Involuntary Motor Response)
Autonomic Nervous System
 Sympathetic Nervous System
 Stress
 Heart rate increases.
 Parasympathetic Nervous
System
 Relax
 Heart rate decreases.

51. Meninges

52. Meninges -These are the
membranous
coverings of
C.N.S.
These are fibrous
connective tissues.

53. Brain and spinal cord are
surrounded by three layers
of meninges.
 Outer - Dura mater,
 Middle - Arachnoid
mater &
 Inner - Pia mater.

54. The space between arachnoid mater and
pia mater is known as subarachnoid
space.
This space is filled with a fluid called
cerebrospinal fluid.
Brain and spinal cord are actually
suspended in the cerebrospinal fluid.

55. Pia Mater -
Pia = Soft.
Mater = Mother.
Inner most connective tissue layer.
Highly vascular.
Very thin & delicate.
Closely covering all the surfaces of brain & Spinal Cord.

56. Arachnoid Mater -
Arachnoid = Spider like.
Present outside the Pia Mater.
Connected to pia mater through
Trabecula.
Relatively Non – Vascular.

57. Dura Mater -
Dura = Tough
Mater = Mother.
It is very tough & Strong .
Avascular .

58.  In Relation to Skull – Dura Mater has two
layers –
A. Periosteal Layer – stick to skull bone .
Outer layer.
B. Meningeal Layer – inner Layer.
 Periosteal layer as a part of Skull bone.

60.  Physiologically these two layers are close to each other.
Dural Venous Sinus – these two layers are separated
from each other at some places.
V – shaped space is formed.
Lined by endothelial cells.
Venous blood is running.

61. Meningeal vessels/ Arteries
& veins are present between
Skull bone/Periosteal Layer
& Meningeal layer of dura
mater in temporal region.
Supply blood to meninges .

62. Dural Folds
 Falx Cerebri – A double fold of dura
mater passes through interhemispheric
fissure. - Separating two cerebral
hemisphere.
 Tentorium Cerebelli – Continuation of
falx cerebri above the roof of cerebellum .
 It separates occipital & temporal lobes of
cerebrum from cerebellum & Brainstem.
 Falx Cerebelli – in between
cerebellum hemisphere.

63. Clinical Importance of
Meninges

64. 1. Epidural Hemorrhage -
Epidural Hematoma/bleeding.
 Collection of blood between
skull/periosteal layer & meningeal
layer of dura mater.
 Dura mater is tightly connected to
suture.
Lens shaped/Biconvex shaped
hemorrhage is

65. Cause of Epidural Hemorrhage -
occur due to trauma to the
skull ,mostly on temporal side.
There is rupture of meningeal arties
& veins.

66. 2. Subdural Hemorrhage -
Collection of blood below the dura mater/outer
layer of dura mater & Arachnoid membrane.
Cause- injury to cerebral vein.
Cresent/sickle shaped hemorrhage with H/O fall
after intoxication or injury due to neck movement
(with increasing age = grey mater shrinks)
Cerebral vein passes through – pia mater-
arachnoid matter – dura mater- dural veinous sinus.

68. 3. Sub- Arachnoid Hemorrhage -
Below Arachnoid membrane or between
Pia Mater & Arachnoid membrane.
Occur due to rupture of cerebral
Aneurysm.

69. Lumbar
Puncture at the
level of L3-L4
& L4-L5 –
Confirmation of
Sub-
Arachnoidal
Hemorrhage.
(blood & C.S.F)