Body Tissues

Epithelial Connective

Tissues

Muscle Nervous

Nervous system

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Conducts nerve impulses between body structures and

controls body functions
Functions
• Sensory Internal

External
• Integration> Analysis> storage>interpret>decide
• Motor> Response
• Regulates all activity (Voluntary & Involuntary)
• Adjust according to changing external and internal environment

Nervous System

Subdivisions:

CNS (Central Nervous System)

PNS( Peripheral Nervous System)

ANS (Autonomic Nervous system)

Nervous tissue – Cell Types
Functionally
• Neuron (Nerve Cell) -Conduction

Variable Shape , Size, Function

• Neuroglia – Supportive
— Macroglia
— Microglia

• Ependymal Cells
• Schwann Cells – In PNS

Neuron ( Nerve Cell)

Components

1.Cell Body

2.Cell Processes (Neurites)

Cell Body – Size vary from 5 µm – 120 µm
(Perikaryon) – Plasma membrane

Nucleus
Cytoplasm
Axon Hillock
Neuronal Skeleton

Cell Processes

1.Dendrites : Short , irregular thickness. Freely
Branching, Afferent processes , Contain Nissl
Granules

2. Axon –
Long , Single, Efferent process of Uniform

Diameter, Devoid of Nissl Granules, Ensheathed
by Schwann cells, Gives collateral branches
Terminal branches called telodendria (axon
terminals)

Terminate – within CNS – Always with another
neuron
Outside CNS – Either may end in relation to

the effector organ or Synapse
with neurons of Peripheral ganglia

Types Of Neuron
1.Acc. To no of Processes

Bipolar
Multipolar
Pseudounipolar

2. Acc. To Function
Sensory
Motor

3. Acc. To Axon Length
Golgi type-1(long)
Golgi type-II

Synapse
site of junction of
neuron

Types
Axo- Dendritic
Axo – Somatic
Axo- Axonal

Neuroglia
• Astrocytes : Fibrous

Protoplasmic
Metabolism of neurotransmitters
K+ Balance
Contribute in brain development
Blood brain barrier
Link between neurons and blood

vessels
• Oligodendrocytes:

Form a supporting network
around neurons
Produce myelin sheath around
several neurons

Neuroglia- contd.
• Microglia: Phagocytic

cells; Migrate to area of
injured nervous tissue.

• Ependymal cells: Line the
ventricles of brain and
central canal of SC.

Form CSF and assist in its
circulation.

• Schwann cells: Produce a
part of myelin sheath
around a single axon of a
PNS neuron.

• Satellite cells: Flattened
cells around neurons in
ganglia; support neurons

Cell bodies
• Grey matter & Nuclei – in CNS
• Ganglia in PNS

Cell processes
• Form tracts in CNS
• Nerves in PNS

Arrangement of grey and white mater

Proportion of grey and white matter vary at different
levels

CNS
Brain

Spinal Cord

BRAIN
Content of Cranial cavity
Covered with membranes

(Meninges)
•Dura matter
•Arachnoid matter
•Pia matter

Parts

• Cerebrum
• Cerebellum
• Brain Stem

-Mid Brain
-Pons
-Medulla

Spinal Cord

• Content of vertebral canal
• Almost rounded in shape
• Covered with meninges
• From F. magnum – Lower

border of L1 Vertebra

33 Vertebrae
7 Cervical
12 Thoracic
5 Lumbar
5 Sacral
4 Coccygeal

PNS ( Peripheral Nervous system)
Two Components
1. Somatic (Cerebrospinal)

—12 Pair Cranial Nerves
—-31 pair Spinal Nerves

2. Visceral ( Autonomic Nervous System – ANS)
—-Visceral or Splanchnic nerves

two – subdivisions
i) Sympathetic
ii) Parasympathetic

From outside – inward

•Epineurium – whole nerve trunk

Perineurium –each fasciculus

Endoneurium – Each nerve fiber

Nerve – composed of bundle (Fasciculi) of nerve fibers (axon with)
its covering bounded by connective tissue sheath

Somatic Component
• Deals with any change in external

environment – Extroceptive or Proprioceptive
General Sensations like
• Pain , Touch , Temp. — From Skin
• Sensations from muscles , bones , joints, limbs
Special Sensations like
• Vision
• Hearing
• Balancing – Through vestibular receptors

Cranial Nerves

1. OLFACTORY 7. FACIAL
2. OPTIC 8. VESTIBULO-COCLEAR
3. OCCULOMOTOR 9. GLOSSOPHARYNGEAL
4. TROCHLEAR 10. VAGUS
5. TRIGERMINAL 11. ACCESSORY
6. ABDUCENT 12. HYPOGLOSSAL

31 Pairs
Spinal

Nerves
Includes
Cervical -8 (C1 —-C8)
Thoracic -12 (T1-T12)
Lumbar – 5 (L1-L5)
Sacral – 5 (S1– S5)
Coccyx – 1 (Co -1)

Spinal Nerve
Joining of anterior (ventral) and Posterior (dorsal)
nerve roots arising from rootlets

Spinal Segment
Length of the spinal cord originating rootlets of one
spinal nerve

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Spinal Nerve
Dorsal Root & Ventral Root
Join to form trunk of spinal nerve
At intervertebral foramina

divide into Dorsal and ventral ramus

Dorsal ramus runs posteriorly and
divide in Medial and Lateral Branches
to supply muscles of back, and give
Cut. Branches

Ventral ramus runs anteriorly and give
lateral cutaneous br. which further
subdivide In Anterior and Posterior
branches
Rest continue as Ant. Cut. Branch

Dermatome – Area of the skin supplied by a single segment
of spinal cord

Root
Trunk
Ramus

Ventral Rami of Cervical, Lumbar.
Sacral and Coccygeal nerves join
To form Nerve Plexuses