1. THE NERVEOUS SYSTEM

3. THE BRAIN

4. 1.Constitutes about one-fifth of body
weight
2.Lies within the cranial cavity.
3.Parts are:
-cereberum
-midbrain
-pons
-medulla oblongata
-cerebellum

5. CEREBRUM
1.Occupies the anterior and middle cranial
fossae.
2.Divided by a deep cleft,the longitudinal
cerebral fissure into right and left cerebral
hemisphere,each containing one of the lateral
ventricles.
3.The hemispheres connected by a mass of white
matter called corpus callosum.
4.Divided into lobes which take the names of the
bones of the cranium:
-frontal
-parietal
-temporal
-occipital

6. INFERIOR OF THE CEREBRUM
1.Surface of the cerebral cortex composed
of gray matter.
2.the lobes connected by masses of nerve
fibres or tract.
Association(arcuate)-connect different
parts of a cerebral hemisphere by
extending from one gyrus to another.
Commissural tract-connect corresponding
areas of the two cerebral hemisphere.
Projection tract-connect the cerebral cortex
with grey matter of lower part of the brain
and with the spinal cord.

7. Function of the cerebral
cortex
1.Mental activities
ex:memory,thinking,intelligence,moral
sense,learning,reasoning
2.Sensory perception
Ex:the perception of the
pain,temperature,touch,hearing,taste,smell,
sight
3.Initiation and control of skeletal(voluntary)
muscle contraction.

8. Functional areas of cerebral
Functional areas of cerebral cortex
cortex
1.Somatic sensory area – receives
impulses from the body’s sensory
receptors
2.Primary motor area – sends impulses to
skeletal muscles
3.Association-intergration nad processing
of complex mental function

9. Motor area of the of the cerebral cortex
a)Primary motor area-control voluntary
contraction of specific muscle on the opposite
side of the body.e.g:finger maneuver
(b)broca’s (motor speech) area-involve in the
translation of thoughts into speech
Sensory areas of the cerebral cortex
(a)Somatosensory area-sensation of
pain,temperature,pressure and touch,awareness of
muscular movement and the position of joints are
perceived.
(b)Auditory area-nerve cells receive and interpet
impulses transmitted from inner ear by the cochlear.

10. c)Olfactory area-impulses from the
nose,transmitted via the olfactory
nerves.
(d)Taste area-impulses from sensory
receptors in taste buds are received
and perceived as taste
(e)Visual area-optic nerve pass from
the eye to this area,which receive and
interprets the impulses as visual
impression.

12. Association area
(a)Premotor area-neurones coordinate
movement initiated by the primary
motor cortex.
(b)Prefrontal area-intellectual function
controlled such as perception and
comprehension of passage of time.
(c)wernicke’s (sensory speech)area-the
spoken word is perceived and
comprehension and intelligence are
based.
(d)parieto-occipitotemporal area-
spatial awareness,interpreting written
language and ability to name object.

13. Others areas of the cerebrum
BASAL GANGLIA
1.Lying deep within the cerebral hemisphere.
2.Involved in initiation and fine control of complex
movement and learned coordinated activities
THALAMUS
1.Consist of two masses of nerve sense and fibres
situated within cerebral hemisphere.
2.Sensory input from the skin,viscera and special
sense organ is relayed to thalamus

14. HYPOTHALAMUS
1.Situated below and in front of the
thalamus,above the pituitary gland.
2.Funtion are:
-the autonomic nervous system
-appetite and satiety
-thirst and water balance
-body temperature
-emotional reaction
-sexual behaviour
-biological clocks

15. BRAIN STEM
MIDBRAIN
1.Situated around the cerebral
aqueduct between the
cerebrum above and the pons
below.
2.Consist of nucleic and nerve
fibres(tract).
3.Nucleic act as relay station for
the ascending and descending
nerve fibres.

16. PONS
1.Situated in front of the cerebellum,below the
midbrain and above the medulla oblongata.
2.Nucleic within the pons that act as relay station
and associated with the cranial nerves.
MEDULLA OBLONGATA
1.Extend from pons above and is continous with
spinal cord below.
2.Has several special features:
-decussation(crossing) of the
pyramid.motor nervedescending from the motor
area in the cerebrum to the spinal cord in the
pyramidal
tracts.

17. -sensory decussation.sensory nerve
ascending to the cerebrum from the spinal
cord cross from one side to other in the
medulla.
-the cardiovascular
centre(CVC).control the rate and force
cardiac contraction and blood pressure.
-the respiratory centre.control the
rate depth of respiration
-reflex centres.irritants present in the
stomach or respiratory tract stimulate the
medulla oblongata,activating the reflex
centres.

18. RETICULAR FORMATION
1.Is a collection of neurones in the core of
the brain stem,surrounded by neural
pathway.
2.function:
-coordination of skeletal muscle activity
associated with voluntary motor movement
and the maintenance of balance.
-coordination of activity controlled by the
autonomic nervous system.
-selective awareness that function through
the reticular activating system(RAS).

19. CEREBELLUM
1.Situated behind the pons and
immediately below the posterior portion
of the cerebrum occupying the posterior
cranial fossae.
2.function:
-coordination of voluntary muscular
movement,posture and balance .
-role in learning and language
processing.

20. SPINAL CORD

21. 1.elongated,almost cylindrical part of the
CNS.
2.Continuos above with the medulla
oblongata and extend from the upper
border of the atlas to the lower border
of the 1st lumbar.
3.Is the nervous tissue link between the
brain and the rest of the body.
4.Incompletely divided into two equal
parts,anteriorly by a short,shallow
median fissure and posteriorly by a deep
narrow septum.

22. GREY
MATTER
1.Have 2 posterior,2 anterior and 2
lateral columns.
2.Is the transverse commisure and
it is pierced by the central canal an
extension from the fourth
ventricle.
3.The nerve cell bodies may be:
-sensory neurones,receive
impulses from the periphery of
the body
-lower motor neurones,transmit
impulses to the skeletal muscle.
-connector neurones,form spinal
reflex arcs.

23. POSTERIOR COLUMNS OF GREY
MATTER
1.Composed of cell bodies that
stimulate by sensory impulses
from the periphery.
2.Contribute to the formation of
white matter of the cord and
transmit the sensory impulses
upwards to the brain.
ANTERIOR COLUMNS OF GREY
MATTER
1.Composedof cell bodies of the
lower motor neurones that
stimulate the upper motor
neurnes.

24. WHITE MATTER
1.Arranged in 3
column:anterior,posterior and
lateral.
2.function:
-ascending tract:sensory toward
brain
-descending tract:motor from brain

26. 1.Consist of:
-31 pairs of spinal nerves
-12 pairs of cranial nerves
-the autonomic nervous system
2.Each nerve consist of numerous nerve
fibres collected into bundle and
3.Has covering of protective connective
tissue:
ENDONEURIUM-delicate
tissue,surrounding each individual fibre.
PERINEURIUM-smooth connective
tissue,surrounding each bundle of fibres.
EPINEURIUM-fibrous tissue which
surround and encloses a number of
bundles of nerve fibres

27. 1. 31 pairs of spinal nerves that leave the vertebral canal.
-8 cervical
-12 thoracic
-5 lumbar
-5 sacral
-1 coccygeal
2. Nerve is formed by the union:
Mixed nerves – both sensory and motor fibers
Afferent (sensory) nerves – carry impulses toward the
CNS
Efferent (motor) nerves – carry impulses away from the
CNS
3.The Anterior Nerve root
-consists of motor nerve fibres.
The Posterior nerve root:
-consists of sensory nerve fibres

29. PLEXUSUS
•Cervical
•Brachial
•Lumbar
•Sacral

30. CERVICAL PLEXUS
1.Cervical plexus (C1-C4) innervates the
muscles and skin of the neck and shoulder.
2.The superficial branches supply the
structures at the back and side of the head
and skin of the front of neck.
3.The deep branches supply muscle of the
neck.e.g:the sternoleidomastoid

31. BRACHIAL PLEXUS
Main nerves (be able to
label):
•Musculocutaneous C8,T1 –passes
downwards to the lateral aspect of
the forearm.
•Median C5,6,7,8,T1 – passes down
the midline of arm in close
association with the brachial artery.
•Ulnar C7,8,T1 – passes behind the
medial epicondyle of humerus.
•Axillary C5,6– winds round the
humerus at the level of the surgical
neck.
•Radial C5,6,7,8,T1– to posterior
part of limb
31

32. LUMBAR PLEXUS
1.Formed by anterior rami of the L1-L4.
2.Lies within the psoas major muscle.
3.Main branches:
-iliohypogastric nerve L1
-ilioinguinal nerve L1
-genitofemoral L1,2
-lateral cutaneous nerve of thigh L2,3
(supplies the skin of the lateral aspect o
thigh)
-femoral nerve L2,3,4 (passes behind the
inguinal ligament to enter thigh)
-obturator nerve L2,3,4 (supplies the
adductor muscle of thigh and skin of the
medial aspect of thigh)
-lumbosacral trunk L4,5 (trunk dsecends
into the pelvis)

34. SACRAL PLEXUS
1. formed L4-S4
2.Supplies muscles and skin of
posterior thigh and almost all of the
leg
3.Main branch is the large sciatic
nerve, which consists of:
Tibial nerve – to most of hamstrings, calf
and sole
Common fibular nerve – to muscles of
anterior and lateral leg and skin
4.Other branches supply pelvic girdle
(gluteus muscles) and perineum
(pudental nerve)

35. COCCYGEAL PLEXUS
1.Formed by part of the
4th and 5th sacral and the
coccygeal nerves.
2.Supply the skin around
the coccyx and anal area

36. 1.Do not intermingle to
form plexus.
2.There are 12 pairs and 11
are the intercoastal nerves
and 12th pair comprise the
subcostal nerves.
3.The 7th to 12th nerves
supply the muscle and skin
of the posterior and
anterior abdominal wall

37. 1.There are 12 pairs of cranial nerves
originating from nucleic in the inferior surface
of the brain,some sensory,some motor and
some mixed.
2.Names and numbers:
I. olfactory:sensory
II. Optic:sensory
III. Oculomotor:motor
IV. Trochlear:motor
V. Trigeminal:mixed
VI. Abducent:motor
VII.Facial:mixed
VIII.Vestibulocochlear(auditory):sensory
IX. Glossopharyngeal:mixed
X. Vagus:mixed
XI. Accessory:motor
XII.Hypoglossal:motor

38. CN Name Attached Foramen Function
# to
I Olfactory Forebrain Cribriform Sense of smell
plate
II Optic Forebrain Optic canal Sense of vision (sight)
from retina
III Oculomotor Midbrain Superior Motor to 4 of the 6
(brainste orbital muscles of eye
m) fissure movement (up & in);
eyelid; constriction of
pupil
IV Trochlear Midbrain Superior Motor to superior
(brainste orbital oblique muscle of eye
m) fissure (down & out)
V Trigeminal Pons V1: superior All three divisions: facial
V1 (brainste orbital sensation
ophthalmic m) fissure
V2 maxillary V2: foramen
V3 rotundum V3 (mandibular
mandibular V3: foramen division): chewing also
ovale

39. VI Abducens Pons Superior orbital Motor to lateral rectus muscle
(brainstem) fissure of eye (abducts outwards)
VII Facial Pons Internal Facial expression (motor)
(brainstem) auditory canal Taste anterior 2/3 tongue
Salivary & lacrimal glands
(saliva and tears)
VIII Vestibulocochlear Pons Internal Equilibrium (vestibular)
(brainstem) auditory Hearing (cochlear)
canal
IX Glossopharyngeal Medulla Jugular Taste & touch from posterior
(brainstem) foramen 1/3 tongue (sour, bitter);
pharynx (throat) muscles of
swallowing; parotid gland
(saliva); senses carotid BP
X Vagus Medulla Jugular Senses aortic BP, slows heart
(brainstem) foramen rate, stimulates digestive
organs; larynx (vocal cords),
taste, swallowing
XI Accessory Medulla Jugular Sternocleidomastoid, trapezius,
(brainstem) foramen swallowing; part joins Vagus
XII Hypoglossal Medulla Hypoglossal Innervation of tongue muscles
(brainstem) canal

40. TH@NK YOU