1. Nervous System Structure and organization of the nervous system
CHAPTER 8
Structure and organization of the nervous system
Functions of different parts of the nervous system
Tools to study nervous system
Dr. Hameed Al-Sarraf
Dept. Physiology

2. Nervous System

3. Nervous System Peripheral Nervous System (PNS) Central Nervous
System (CNS)
Brain:
Memory
Emotions
Thoughts
Body regulation
and control
Peripheral Nerves:
Afferent (sensory)
Efferent (motor)
Spinal Cord:
Place for many
nerve pathways,
Control of reflex
activities

4. Relations Between CNS and PNS
Sensory
Receptors from:
Skin, deep tissue,
Eyes, ears, etc
Interneurones
Motor
Effectors:
Muscles and
Glands

5. CNS (Brain and Spinal Cord)

6. Development of CNS
PNS
CNS

7. Cerebrospinal Fluid (CSF)
- Fluid surrounding the brain and spinal cord. This fluid is mainly secreted by
a structure in the brain called choroid plexus. CSF flows around the brain and
in the cavities inside the brain (ventricles).
CSF helps brain float in the
skull reducing the weight
of the brain by 30 folds.
Choroid
Plexus
CSF

8. Brain Ventricles

9. Brain and its Divisions Brain is encased in cranial cavity, its
divided into six
parts:
1- Cerebrum
2- Diencephalon
3- Mesencephalon
4- Cerebellum
5- Pons
6- Medulla oblongata

10. Cerebrum
- The largest portion of the brain (80%). Responsible for higher mental functions
Consist of right and left hemispheres. Hemispheres are connected by a large fiber
tract called corpus callosum.

11. Cerebral cortex - Outer layer of cerebrum is called cerebral cortex
gray matter and white matter
- Folds and grooves in cortex are called convolusions:
Folds = Gyri (gyrus = single fold), Grooves = sulci (sulcus = single groove).
- Deep sulci also called:
Fissure.
- Fissures divide cerebral
cortex into 5 lobes:
1- frontal
2- pareietal
3- temporal
4- occipital,
5- insula

12. Cerebral cortex - Outer layer of cerebrum is called cerebral cortex
gray matter and white matter
- Folds and grooves in cortex are called convolusions:
Folds = Gyri (gyrus = single fold), Grooves = sulci (sulcus = single groove).
- Deep sulci also called:
Fissure.
- Fissures divide cerebral
cortex into 5 lobes:
1- frontal
2- pareietal
3- temporal
4- occipital,
5- insula

13. Functions of the Cerebral lobes
Frontal : Voluntary motor control, Speech, Personality, Higher intellectual processes (planning, concentration & decision making).
Parietal : Sensory somatesthetic sensation, speech.
Temporal : Interpretation of Auditory sensation, storage (memory) of auditory and visual experiences.
Occipital : Vision, Movements of eyes.
Insula : Memory, sensory (pain) and visceral integration.

14. Motor and Sensory areas of
Cerebral cortex
Postcentral Gyrus
Precentral Gyrus

15. Tools for Studying the brain
1- Visualizing the Brain :
a) X-ray Computed Tomography (CT-Scan)
b) Positron-Emission Tomography (PET-Scan)
c) Magnetic Resonance Imaging (MRI)
2- Detection of Electrical Waves :
Electroencephalogram (EEG)
EEG waves = alpha, beta, theta, and delta

16. PET- Scanner
CT- Scanner
MRI

17. Visualizing the Brain
CT-Scan
PET-Scan
MRI

18. Recording EEG

19. EEG Waves Alpha waves- (10-12 cycles/sec)
recorded in parietal and occipital regions
while awake & relaxed.
Beta waves- (13-25 cycles/sec)
recorded in frontal lobs. Produced by
visual stimuli and mental activity.
Theta waves- ( 5-8 cycles/sec)
recorded in temporal & occipital lobs.
Common in infants (newborn)
In adults it’s a sign of emotional stress.
Delta waves- (1-5 cycles/sec)
recorded in general pattern of cerebral
Cortex. Observed during sleep. If seen in
Awake person it’s a sign of damage.

20. Basal Nuclei Precentral Gyrus
Nucleus = a collection of neuron cell bodies in the CNS. Basal nuclei = masses of gray matter (neuron cell bodies) located deep in white matter of cerebrum.
Function of basal nuclei =
Control of voluntary movements of body.
Precentral Gyrus

21. Decussation = crossing over of fibers
Each cerebral hemisphere controls
movements (motor fibers) of the opposite
side of the body.
Also each cerebral hemisphere receives
sensation (sensory fibers) from the opposite
This is due to decussation (crossing over) of
fibers.
Both cerebral hemipheres also receive
information from both sides of the body
this is due to cerebral hemispheres are
connected and communicated with each other
by a large tract of fibers called corpus
callosum.

22. Language
Aphasias = speech and language disorders caused by damage to the brain (head injury/stroke)
Broca’s aphasia – weakness in right arm and right side of face. They understand
Speech but they are slow talkers and their speech is poorly articulated. Understand
A sentence but have difficulty repeating it.
Wernicke’s aphasia – rapid and fluid speech but without meanings (word salad).
Comprehesion (written and spoken) is also impaired.
Conduction aphasia- damage to arcuate
faciculus which connects Broca and
Wernicke. Fluent but nonsensical speech
like Wericke’s aphasia. Inflect
Angular gyrus damage- its an area
between parietal, temporal and occipital lobs. Difficulty in writting and reading, but spoken language is understood.