The central nervous system (CNS) is a complex network of nerve tissues, comprising the brain and spinal cord, which control bodily functions through neurons. It includes grey matter, which processes signals, and white matter, which contains myelinated axons connecting different areas. The brain, as the most complex organ, is responsible for intelligence, sensory interpretation, and regulation of behavior, while the spinal cord acts as a conduit for messages between the brain and the body.

1. Central
Nervous
System

2. What is CNS?
• Part of Nervous System
• A complex of nerve tissues that control activities of the body.
• Called central as it is the body’s main control centre.
• Consist of:
Brain (Protected by Skull)
Spinal Cord (Protected by Vertebral Column)
As the basic building blocks of Nervous System is
Neuron, same is the case with Central Nervous System

4. Neuron or Nerve Cell

5. • Specialized cell that transmit nerve impulses to communicate with in
nervous system and with other systems.
• Supported by Glial cells.
• May be sensory, motor or interneurons.
• Consists of;
 Cell body or Soma
 Axon
 Dendrites
 The neurons of CNS are multipolar.

6. CELL BODY:
• Forms Grey matter of CNS.
• Contains nucleus, cytoplasm, organelles, and other cell
structures.
• Does not contain centrosome so does not undergo division.
AXON:
• Forms White matter of CNS.
• Carries signals away from the cell body.
• Covered by a membrane called Axolemma.
• Is a long nerve process which branches out.
• May or may not be coated with myelin sheath.(if coated then
Nodes of Ranvier are also present)
• End as synapse (connection to other neuron’s dendrites)
DENDRITES:
• Carry signals toward the cell body.
• More numerous, shorter, and more branched than axons.
• Make synapses (connection to other neuron’s axons)

7. Synapse

8. • Junction between 2 neurons where the signal is passed on
from pre-synaptic neuron’s axon to a post-synaptic neuron’s
dendrite.
• Space between pre- and post-synaptic neurons is called
Synaptic cleft.
• May be Chemical or Electrical.
• Chemical synapses transmit signals through
neurotransmitters.
• Electrical synapses transmit signals through ions.

9. Synapse
Transmission
Chemical Synapse Electrical Synapse

11. Grey and White
Matter
SPINAL CORD BRAIN

12. GREY MATTER:
• Contains neuron
soma
• Have processing
units.
• Present innerly in
spinal cord.
• Mostly present
outerly in brain.
WHITE MATTER:
• Contain myelinated
axons
• Provide connection
between grey
matter units.
• Present outerly in
spinal cord.
• Present innerly in
brain.

13. SPINAL CORD:
• White Matter:
-present outside
• Grey Matter:
-present inside
-butterfly shaped
BRAIN:
• White Matter:
-present inside
• Grey Matter:
-present outside as ;
1.cerebral cortex
2.cerebellar cortex
-little present inside as nuclei

14. Spinal Cord

15. • As long as about 18 inches, thin, cylindrical and tube like structure.
• A very delicate structure that contains nerve bundles and cells that
carry messages from brain to rest of your body and vice versa.
• Starts posteriorly, from medulla oblongata (brain stem) and
extends down to form cone shaped Conus Medullaris.
• Protected by the bony structure called vertebral column.
• It gives rise to the 31 pairs of spinal nerves (part of PNS).
• Covered by 3 layers of meninges for more protection;
 Dura Matter (outer layer)
 Arachnoid Matter (middle layer)
 Pia Matter (inner layer)
• CSF, a shock absorbing fluid that also
has a protective function, is present
between meninges.

17. The Spinal cord is divided into 5 different parts on the basis of specific
spinal nerves that arise from that region;
1. Cervical cord
2. Thoracic cord
3. Lumbar cord
4. Sacral cord
5. Coccygeal cord

18. Brain

19. • Most complex organ.
• Weighs about 3 pounds.
• Is the seat of intelligence, interpreter of the
senses, initiator of body movement, and
controller of behavior.
• Source of all the qualities that define our
humanity.
• Protected by skull, meninges and CSF.
• Does not contain muscle
• Contains blood vessels and nerves.
• Attached to spinal cord at foramen magnum.

20. Parts of Brain
• Cerebrum
• Thalamus
• Hypothalamus
• Midbrain
• Pons
• Medulla oblongata
• Cerebellum
Diencephalon
Brain stem

22. CEREBRUM
• Largest and heaviest part of brain
• Has grey matter at its periphery as Cerebral Cortex and white matter
at centre as Tracts.
• Divided into 2 hemispheres by Longitudinal Cerebral Fissure.
• A fold of dura matter with in the fissure called Falx Cerebri separates
the hemispheres.
• A mass of white matter called Corpus Callosum connects the
hemispheres.
• The left hemisphere controls the right side of body and vice versa.
• Each hemisphere is divided into 4 lobes;
Frontal
Parietal
Temporal
Occipital

23. Lobes of Cerebrum

24. FRONTAL LOBE:
• Also called Motor Cortex.
• Anterior and largest lobe.
• Separated from parietal lobe by Central Sulcus.
• Involved in processing and responding functions.
PARIETAL LOBE:
• also called Sensory Cortex.
• Superior lobe.
• Involved in sensing pain and touch like sensations.

25. TEMPORAL LOBE:
• Also called Auditory cortex.
• Lateral lobe.
• Separated from parietal lobe by Lateral Sulcus.
• Involved in hearing, balance and some degree of smell
recognition.
OCCIPITAL LOBE:
• Also called Visual Cortex.
• Posterior lobe.
• Separated from parietal lobe by Parieto-occipital Sulcus.
• Involved with vision.

26. Diencephalon
• Connection between cerebrum and midbrain (part of brain stem)
• Mainly consists of thalamus and hypothalamus
• Other structures include optic chiasma and pineal gland and
posterior lobe of pituitary gland.

27. THALAMUS:
• Largest mass of grey matter of the diencephalon that includes nuclei.
• Its superior part is covered by a thin layer of white matter.
• It is situated within the hemispheres below corpus callosum.
• Involved in relaying of sensory and motor signals, and the regulation
of consciousness, sleep, and alertness, processing of emotions and
complex reflexes.
HYPOTHALAMUS:
• Consists of a number of nuclei.
• Lies below and anteriorly to thalamus.
• Linked to anterior pituitary by blood vessels and posterior pituitary by
nerve fibers.
• Involved in regulation of eating and drinking behaviour, sexual
activity, reproduction, control of autonomic activity, regulation of
emotional behaviour, control of endocrine activities, response to
stress and temperature regulation.

29. Brain stem
• Stem-shaped structure, extending down from the posterior
(back) part of the brain to the spinal cord.
• Connection between brain and spinal cord
• Consists of ;
Midbrain
Pons
Medulla oblongata

31. MIDBRAIN:
• located below cerebral cortex and at the topmost part of brainstem.
• It is sandwiched between the diencephalon.
• Consists of nuclei and tracts.
• Involved in consciousness, sleep-wake cycles, autonomic functions and
relaying impulses.
PONS:
• Below midbrain, middle part of brainstem, located anterior to
the cerebellum.
• Its primary role is to serve as a bridge, linking different regions of the CNS,
such as the cerebellum and the cerebrum.
• Also involved in regulation of breathing, sleep-wake cycle and even
generating dreams.
MEDULLA OBLONGATA:
• Cone-shaped structure below pons, inferior part of brainstem.
• Contains white matter at periphery and grey matter centrally.
• Has a Cardiovascular centre, Respiratory centre and Reflex centre of vomiting,
coughing, sneezing and swallowing.

32. Cerebellum

33. • Situated behind the pons and posteriorly below
cerebrum.
• An ovoid-shaped structure.
• Divided into 2 hemispheres by Vermis and Falx
cerebelli.
• Grey matter is present at periphery and the white
matter in centre.
• Involved in control and movements of skeletal
muscle, maintenance of posture, balance and
equilibrium, learning and language processing.

35. QuestioningSession