The nervous system is divided into the central nervous system (CNS) and peripheral nervous system (PNS). The CNS comprises the brain and spinal cord and is responsible for sensory integration, coordination of motor actions. The PNS includes cranial and spinal nerves and connects to the CNS, carrying sensory information in and motor commands out. The brain is divided into the cerebrum, brainstem, and cerebellum. The cerebrum is the largest part and is divided into lobes. The brainstem connects the cerebrum to the spinal cord and contains nuclei that control vital functions. The cerebellum coordinates movement.

1. THE NERVOUS
SYSTEM

2. CELLULAR ARCHITECTURE
NEURONS
(the structural and functional unit of nervous tissue)
NEUROGLIAL CELLS
(supporting tissue)

3. DIVISONS OF NERVOUS SYSTEM
It is divided into :
 Central Nervous System (CNS) which
comprises brain and spinal cord. It is
responsible for integrating, coordinating the
sensory information and ordering appropriate
motor actions.
 Peripheral Nervous System (PNS) includes 12
pairs of cranial nerves and 31 pairs of spinal
nerves. These provides afferent impulses to
CNS and carries efferent impulses to muscles,
glands and blood vessels.

4. THE BRAIN
Human Brain is divided into three main parts on the
basis of their functions and placements.
The three main parts of the human brain are :
 CEREBRUM
 BRAIN STEM
 CEREBELLUM
MIDBRAIN
PONS
MEDULLA OBLONGATA

5. DEVELOPMENT OF : THE BRAIN

7. CEREBRUM
• Largest part of the brain
• Outer grey matter and inner white matter
• Made up of two cerebral hemispheres;
incompletely separated by median
Longitudinal Fissure.
• Each hemisphere contains a cavity –
Lateral Ventricle.
• There are four lobes :
Frontal Lobe
Parietal Lobe
Temporal Lobe
Occipital Lobe
Insula (deep within the Lateral sulcus)

8. FUNCTIONAL AREAS OF CEREBRAL CORTEX

9. THALAMUS

10. HYPOTHALAMUS
The Hypothalamus is part of the diencephalon. It lies in the floor
and lateral wall of the third ventricle. It’s functions are :
• Endocrine control
• Neurosecretion
• General autonomic effect
• Temperature regulation
• Regulation of food and water intake
• Sexual behavior and reproduction
• Biological clocks
• Emotion, fear, rage, aversion, pleasure and reward

11. LIMBIC SYSTEM
• The Limbic System is a complex network of cortical
areas and subcortical structures interconnected by
directional pathways.
 Major limbic centers includes:
• The Cortical Areas : cingulate gyrus,
orbitotofrontal, insular and medial prefrontal
cortices and parahippocampal gyrus.
• Subcortical Structures including : The thalamus,
septal area ,nucleus accumbens, hippocampus,
hypothalamus and the amygdala.
 Connecting pathways of limbic system:
• The alveus, the fimbria, the fornix,
mammilllothalamic tract and the stria terminalis

12. BRAIN STEM
• Located between the cerebrum and the spinal cord – provides a
pathway for tracts running between higher and lower neural
centers.
• Consists of the Midbrain, Pons and Medulla Oblongata.
• It consists of deep gray matter surrounded by white matter fiber
tracts.
• Produce automatic behaviors necessary for survival.
• Each part of brainstem is connected to cerebellum by Cerebellar
Peduncles(superior, middle and inferior)
• Contains groups of nuclei and related fibers known as Reticulur
Formation.
• It is responsible for : control of level of consciousness,
perception of pain, regulation of cardiovascular and respiratory
systems.
• Site of origin of Cranial Nerves ( from 3rd to 12th )

13. MIDBRAIN
• The Midbrain develops from mesencephalon.
• Connects the pons and cerebellum with the
forebrain.
• It comprises two lateral halves called cerebral
peduncles which is again divided into: Anterior part
– Crus Cerebri and Posterior part – Tegmentum, by
a pigmented band of gray matter - Substantia Nigra
• The central narrow cavity is called the Cerebral
Aqueduct which connects 3rd and 4th ventricles.
• The Tectum is the part of the midbrain posterior to
the cerebral aqueduct; it has four small surface
swellings reffered as two Superior Colliculi and two
Inferior Colliculi.
• The Tegmentum forms the floor of mid brain.

14. PONS
• Located in the rostral to the medulla oblongata,
caudal to the mid brain and ventral to the
cerebellum
 Functions:
• Relays sensory information between the cerebrum
and cerebellum
• Some theories say that it has a role in dreaming.
• Control of respiration: The Apneustic Center-
lower pons and The Pneumotaxic Center - upper
pons
• A number of cranial nerve nuclei are present in it:
the trigeminal nerve, abducens nucleus,
vestibulicochlear nuclei and facial nerve nucleus.

15. MEDULLA OBLONGATA
The Medulla Oblongata lies between the Pons and the
Spinal Cord. It contains centers which control key,
autonomic body functions and it relays nerve signals
between the brain and spinal cord. Important control
centers include:
• The Respiratory Center - controls the rate, rhythm
and depth of breathing
• The Cardiac Center - regulates heart beat
• The Vasomotor Center - controls blood pressure
• The Reflex Centers - reflex the centers for vomiting,
coughing, sneezing, hiccupping and swallowing

16. • Cerebellum consists of three lobes- Anterior, Posterior
and Flocculonodular.
• The cerebellum compares the motor plan created in the
cortex with motor performances and functions to
smoothens and coordinate the movements. This is
accompanied by making synaptic contacts with the brain
stem ‘motor’ centers and the cerebral hemispheres.
 Functions :
• Muscle tone
• Coordination goal directed and spontaneous movements
• Posture and balance
• Eye movements
• Motor learning
• Some cognitive functions- language processing,selective
attention
CEREBELLUM
(LITTLE BRAIN)

17. MENINGES
• The Meninges are the membranes covering
the brain and spinal cord for protection.
• The meninges consists of the three
membranes:
 DURAMATER (hard mother)
 ARACHNOID MATER (web like)
 PIAMATER (soft mother)
• The space between the duramater and the
vertebral wall -EPIDURAL SPACE
• The space between the duramater and the
arachnoid mater –SUBDURAL SPACE
• The space between arachnoid mater and
piamater –SUBARACHNOID SPACE

18. • It stretches from the upper border of the Foramen
Magnum to the invertebral disc between the 1st and
2nd lumbar vertebrae.
• In the newborns ,it extends to the level of the 3rd
lumbar vertebrae.
• Due to differential growth of the vertebral column
relative to the spinal cord, the spinal cord segment do
not always correspond to the vertebral levels.
• Has two enlargements, Cervical and Lumbar due to
cells and fibers of the limbs.
• Ends inferiorly in a tapering Conus Medullaris.
• Anchored to the coccyx by meningeal extension -
Filum Terminale.
SPINAL CORD

19. CROSS SECTION OF SPINAL CORD
• Anterior median fissure and Posterior median sulcus
- deep clefts partially separating left and right halves
• Gray matter : neuron cell bodies, dendrites, axons
- divided into horns
 Posterior (dorsal) horn
 Anterior (ventral) horn
 Lateral horn
• White matter : myelinated axons
- divided into three columns
 Ventral
 Dorsal
 Lateral
- Each of these divided into Sensory or Motor tracts.

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