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1. NERVOUS SYSTEM

2. Nervous system is formed by nervous tissue.
• Functions
1.Provides interactions of organism with external environment.
2.Regulation of various life processes.
3.Integration of different parts of organism in the unified
whole..
4.Coordination of the work of organs.
1.Anatomic classification of NS:
• 1A.Central: brain and spinal cord.
• 1B.Peripheral: nerves, nerve endings, nerve ganglia.
•
2.Functional classification of NS:
• 2A.Somatic: innerves ‘soma’-skeletal muscles, skin,
ligaments, tendons.
• 2B.Vegetative: innerves internal organs, vessels, glands:
sympathetic and parasympathetic.

3. CNS:
Meninges of the brain:
1.Dura mater-dense CT, blood and lymphatic vessels, nerve fibers.
There are large venous sinuses in outer layer of dura mater.
2.Arachnoidea, consists of layers:
1)Simple squamous neuroglial epithelium;
2)5-8 layers of cells-meningocytes, similar to fibroblasts.
3)Trabecules(formed by processes of meningocytes and collagen
fibers)
3.Pia mater-loose CT, vessels and nerve fibers. Its surface is
covered by meningothelium.
Pia mater and arachnoidea are continued along cranial and spinal
nerves, accompany blood vessels of the brain, concreted to their
adventitia. Between dura mater and arachnoidea there is subdural
space, and between arachnoidea and pia mater there is
subarachnoid space.

9. Morphological substrate of NS is reflex arch.
Function: realization of typical answer of
organism onto appointed outer or inner irritation
Reflex arches:
1.Simple-consists of 1)sensory and 2)motor
neuron.
2.Complex-consists of 1)sensory , 2)interneuron,
3)motor neuron.

12. Components of NS
 Nerve ganglion-an accumulation of cellbodies of neurons outside the NS.
 Grey matter-a collection of cellbodies of neurons inside the NS: spinal cord
and brain.
 Nerve trunk-totality of nerve fibers which are connected by connective
tissue and located outside the NS. They are afferent and efferent
nerve fibers, may be myelinated and un-myelinated.
 White matter-the totality of myelinated nerve fibers which are located in
CNS(pathways in NS). In each of pathway there are only afferent or only
efferent nerve fibers.

13. The spinal cord

14. Structure of spinal cord

15. Nerve

16. Spinal cord

17. Cross section of spinal cord

18. White matter of spinal cord

19. Somatic NS
 Somatic NS innerves ‘soma’-organs are developed from somites-skin,
skeletal muscles, ligaments and tendons.

20. Somatic reflex arc

21. Somatic reflex arc
 I.Sensory neurons are pseudounipolar:
 I.1)Cellbodies are in nerve ganglia, i.e. in PNS:
 A. In spinal ganglia-thickenings of posterior radices of spinal cord,
 B. In sensory ganglia of the head-along some cranial nerves.
 I.2)Dendrites are coming from the sensory nerve endings in the composition
of different mixed nerves and then in posterior radices of spinal cord.
 I.3)Axons enter the spinal cord: 1)they contact with interneuron. 2) enter
the composition of posterior horns of spinal cord and arise up to nuclei of
medulla oblongata.

22. Somatic reflex arc
 II.Associative neurons:
 I.1)Cellbodies are in grey matter of CNS-cellbody of 1st interneuron is in:
a)spinal cord(posterior or anterior horns) or in b)nuclei of medulla oblongata.
Cellbodies of next interneurons may be in other departments of CNS(cortex
etc.).
 I.2)dendrites are short at the same accumulation of grey matter that
cellbodies.
 I.3)axons are arising up to effector neurons in anterior horns of the same or
neighboring segments or up to other associative neurons (in the brain).

23. Somatic reflex arc
 III.Effector neurons-in somatic NS they are motor neurons innerve
skeletal muscles:
 III.1)dendrites are short.
 III.2)cellbodies are in:
 a)anterior horns of spinal cord
 b)nuclei of cranial nerves(in the brain trunk).
 III.3)axons are in composition of anterior radices get out of spinal cord.
Then they are in composition of mixed nerves getting the effector organs
(in skeletal muscles they form motor plate).
 Result: by the help of this somatic reflex arch unconscious motor reflex
onto irritation of ‘soma’ is realized.

24. Spinal reflex

25. Functions of vegetative NS
 Vegetative NS(autonomic, involuntary) innerves:
 1)tone of vessels and work of the heart;
 2)tone of the bronchi;
 3)heatproduction and heatloosing;
 4)movement and secretion of organs in GIT and UGT;
 5)tone of smooth muscles.
 It controls vegetative functions.

26. Types of vegetative NS
 1.Sympathetic NS is responsible for adaptation to acute
stress:
 1)Increasing of the blood pressure and heart beating;
 2)intensify of the breath;
 3)Increasing of production of energy provides increasing
of temperature of the body and sweating;
 4)Inhibition of movement and secretion of organs in GIT
and evacuation of urinary bladder is also inhibited.
 5)Pupils are dilated.

27. Types of vegetative NS
 2.Parasympathetic NS is responsible for reconstruction :
 1)Decreasing of the tone of vessels and work of the heart;
 2)Breath becomes weaker;
 3)Decreasing of production of energy;
 4)Work of GIT is intensified. Stimulation of evacuation of urinary bladder;
 5)Pupils are got narrow, m.ciliaris is contracted.

28. Components of vegetative NS
 Cellbodies of interneurons in vegetative NS are located
only in appointed regions.
 Cellbodies of effector neurons are located outside of
CNS in vegetative ganglia.
 Nerve fibers are of 2 types:
 1)preganglionic-consists of axons of interneurons,
myelinated.
 2)postganglionic-consists o axons of effector neurons ,
 unmyelinated.
 Mediators:
 1)in vegetative ganglia –acetylcholine(irritation from the
preganglionic fibers onto effector neurons)
 2)in the endings f postganglionic fibers:sympathetic-
adrenalin, parasympathetic-acetylcholine.

29. Comparison between 2 types of NS

30. Reflex arc of sympathetic NS
 I.Sensory neurons(receptor):
 I.1)sensory endings are in inner organs and in the wall of vessels.
 I.2)dendrites are in the composition of mixed nerves(cranial).
 I.3)cellbodies are in the spinal ganglia or in ganglia along cranial nerves.
 II.Associative neurons:
 I.1)cellbodies are in lateral horns of spinal cord on the level of ThI-LIII.
 I.2)axons form preganglionic(myelinated) n.fibers, are going in the composition
of anterior radices of spinal cord, and then are going towards the sympathetic
trunk(in the composition of white connective branches). They are finished in
ganglia of the sympathetic trunk.
 III.Effector neurons:
 III.1)cellbodies are in intramuralis ganglia(in hollow organs they are in
submucous and muscular plexus) or in ganglia near to organ.
 III2)dendrites&axons are short.

31. Reflex arc

32. Nerve trunk
 Nerve trunk(nerve) consists of :
 1.Nerve fibers and 2.Connective
tissue elements with vessels
 1.Nerve fibers:nerve consists mainly of myelinated
nerve fibers. There is an axis cylinder in the center of
these fibers and light myeline sheath surround. It is
light because lipids are dissolved out.

33. 1.Nerve fibers
 Nature of axial cylinders(axons):
 1)dendrite of receptor(sensory)neuron, myelinated.
 2)axon of effector neuron of somatic NS, myelinated.
 3)axon of associative neuron of vegetative NS(preganglionic n.fibers),
myelinated.
 4)axon of effector neuron of sympathetic NS(postganlionic n.fibers),
unmyelinated.
 Unmyelinated axons appear to be surrounded by the thin layer of Schwann
cell’s cytoplasm which forms the sheath of Schwann(neurilemma) of the
unmyelinated n.fibers. Scwann cells are supporting cells for the n.fibers of
peripheral nerves.

34. 2.Connective tissue elements:
 1)Epineurium-envelope is made of connective tissue, there are vessels, fat
cells.
 2)Perineurium-stratums of connective tissue sheath between bundles or
fascicles is formed by many concentric sleeves of flattened epithelioid cells.
Each sleeve has one cell’s thickness, basal lamina of epithelioid cells
intervenes between the successive sleeves.
 Functions: barrier to passage of materials, especially macromolecules, into or
out of the fascicle.
 3)Endoneurium- a thin layer of connective tissue surrounded
 each nerve fiber within the fascicle which is composed of delicate collagenous
and reticular fibers and flattened fibroblasts with spindle-shaped nuclei.

42. Nerve ganglion
 1.Sensory
 2.Sympathetic
 3.Intramuralis(parasympathetic)

43. Sensory(spinal)ganglion
 1.Sensory ganglion-oval thickening of the posterior radix not far from the
bifurcation.
 Radices of spinal cord are anterior(right, left) and posterior(right, left)-
consist of myelinated nerve fibers.
 Fibers of anterior radices-axons of motor neurons and axons of associative
neurons of vegetative NS, efferent pathways.
 Fibers of posterior radices-axons of sensory neurons, afferent pathways.
 After getting out of spinal cord they are connected into craniospinal
ganglia(mixed composition). Place of this connection is called bifurcation of
the craniospinal nerve.

44. Spinal ganglion
 A)Neurocytes: cellbodies are located on peripheral part of the ganglion out
of nerve fibers, pseudounipolar neurons.
 B)Surrounding structures:
 1)satellites or mantle gliocytes;
 2)BM;
 3)connective tissue capsule;
 4)connective tissue elements with vessels.

45. Spinal ganglion

50. Sympathetic ganglion
 Sympathetic ganglion-are in paired sympathetic trunk and in sympathetic
plexus of abdominal cavity.
 1)covered by connective tissue capsule with stratums forming stroma.
 2)cellbodies of neurons are arranged between elements of stroma in irregular
manner.
 3)2 types of neurons are present:
 1.main type-effector neurons of sympathetic NS
 2.additional type-SIF cells(small intense
fluorescented cells).

51. Sympathetic ganlion
 1.Effector neurons :
 multipolar, 1 axon and several short dendrites.
 Synapses : preganglionic(myelinated)nerve fibers from sympathetic centers of
spinal cord form cholinergic synapses with dendrites or cellbodies of these
neurons.
 Axons leave the ganglion forming adrenergic synapses.
 Cellbodies of each of neuron is surrounded by glial cells-satellites, basal
membrane and fine connective tissue cover.
 2.SIF-cells inhibite synaptic transfer from preganglionic onto effector neurons.



53. Intramuralis ganglia
 in the wall of internal organ.
 Neurons are large with basophilic cytoplasm and light nuclei, surrounded by
satellites and connective tissue elements.
 They are of 3 types:
 1.Effector(basic type)-Golgi type I, with long axon. They receive nerve
impulses from cholinergic synapses and send them to effector
structures(e.g.smooth myocytes) of organ where they are located. Also there
are some of effector neurons of sympathetic NS, their axons form
synapses(noradrenaline).
 2.Sensory neurons-Golgi type II. They are multipolar. Dendrites form receptor
endings in the wall of organ. Receiving impulses are sending onto effector
neuron of the same ganglion, forming peripheral reflex arc.
 3.Associative neurons-Golgi type III, receive impulses from sensory neurons
and send them onto effector neuron of neighboring ganglion-forming peripheral
reflex arc with 3 neurons.

64. The spinal cord

65. Development
 1.Development-ventral department of nerve tube. Wall
of the nerve tube is divided on to 3 layers:
 1)inner layer-ependyma-forms ependymoglial cells;
 2)middle layer-forms grey matter(collection of
cellbodies);
 3)outer layer-marginal veil-forms white
matter(myelinated nerve fibers).

66.  The central nervous system forms from the embryonic
neural tube.
 Cranial and spinal nerves form from neural crest cells
that have split off from the developing neural tube.
 The cranial (superior) part of the neural tube expands
and develops into the brain.
 The caudal (inferior) part of the neural tube forms
the spinal cord.

67. 67

68. 68

69. Structure of spinal cod
Envelops:
 1)pia matter; 2)arachnoidea; 3)dura matter.
 3.Grey matter butterfly in shape. Consists of:
 1)posterior horns;
 2)anterior horns;
 3)lateral horns(Th1-L3)-central part of sympathetic nervous system.

70. Components of grey matter
 a)cellbodies of multipolar neurons arranged in groups.;
 b)neuroglial cells, mainly astrocytes(protoplasmic and fibrous). Their
processes are going towards the white matter with formation of numerous
septa with connective tissue elements. Also they form glial membranes
(components of heamatoencephalic barrier) on the surface of the vessels in
grey and white matter.
 c)nerve fibers.

71. The grey matter
 I.Posterior horns consists of cellbodies of interneurons:
 I.1.Neurons of mono-, oligosegment reflex arc-small diffuse inserting
neurons and diffuse bunches of neurons. They are irritated by sensory
neurons(pain, temperature). Axons are coming up to the motorneurons of
anterior horns(1 r several adjacent segments of one or opposite side).
 I.2.Neurons of spinocerebelar reflex arc:
 a)nucleus propria-axons are passing on to opposite side in lateral fascicle;
 b)nucleus thoracis(Clark)-axons are entering the lateral fascicle of the
same side;
 They are irritated by proprioreceptors of skeletal muscles and tendons. Axons
are in the composition of lateral fascicle towards the cerebellum(unconscious
coordination).

72. I.3.Neurons of spinocorticalis reflex arch:
Of nucleus propria , are irritated by receptors of pain,
temperature. Axons arise up to 2-3 segments, passing
to lateral fascicle of opposite side, then to
thalamus(cortex conscious reaction).
I.4.Inhibitory neurons of substance gelatinosa-small
cells controlling sensory information, forming
inhibitory synapses.

73. II.Intermediate zone and lateral horns:
 II.1.Nucleus intermediate medialis- associative neurons irritated by sensory
neurons from receptors of internal organs. Axons are passing up to cells of
lateral intermediate nucleus(lateral horns) or to the
cerebrum(spinothalammic, spinocerebellar tract), visceral sencibility.
 In lower segments (Sa1-Co3)-central neurons of parasympathetic NS, axons
are passing over to pelvic ganglia, forming afferent pathways.

74.  II.2.Nucleus intermediate lateralis is in lateral horns T1-L3.
 Receive signals from sensory neurons which innerve visceral organs, from
neurons of nucleus intermediate medialis, from the brain. Axons are going in
the composition of anterior radices towards the sympathetic nerve ganglia,
forming efferent pathways.

75. III.Anterior horns-motorneurons:
 III.1.Large alfa-motoneurons-the largest cells. Irregular in shape, forming 5
somato-motor nuclei. They receive impulses from:
 1)Efferent pathways from the cortex of the hemispheres(pyramidal pathways)
 2)Axons of associative neurons of simple reflex arch.
 3)Axons of sensory neurons of simple reflex arch.
 Axons of alfa-motorneurons innerve extrafusal muscle fibers(conscious and
absolute reflex).

76. III.2.Small alfa-motorneurons-are under the control of
subcortical nuclei(compex unconscious movement).
III.3.Gamma-motorneurons –are under the control of
reticular formation. Efferent innervation of intrafusal
muscle fibers(delicate regulation of tone of muscles and
conscious contrctions.
III.4.Renshow cells-inhibitory neurons(inhibite all
motorneurons).
III.5.Associative neurons-are in interstitial nucleus of
Cachal, receive signals froom sensory neurons of spinal
ganglia and it to motorneurons of adjacent nuclei.

78. Due to localization of their axons:
1.Radicis neurons-axons form anterior radices(all
motorneurons, neurons of lateral intermediate
nucleus).
2.Fascicle neurons-axons of proper nucleus, nucleus
thoracis, n.intermediate medialis. Afferent pathways.
3.Internal neurons-diffuse inserting neurons,
Renshow cells.

79. White matter-pathways
 1.Fascicle propria: axons of diffuse cells and cells of interstitial nucleus of
Cachal(oligosegment reflex arch).
 2.Posterior fascicle:afferent pathways-f.gracilis of Goll, f.cuneatus of
Burdach(spinoocortical reflex arch, conscious reaction onto proprioreceptors).

80.  3.Lateral fascicle:
 1)Afferent: lateral position,
 A)Spinocerebellar tract(Flechsig and Gowers)-unconscious coordination.
 B)Lateral spinothalamic tract-conscious reaction onto pain and temperature
irritation.
 2)Efferent: central position,
 A)Lateral pyramidal tract;
 B)Rubrospinalis tract(Monacov);
 C)Olivospinalis tract(Bechterev-Gelveg);
 D)Thalamospinalis tract.

81.  4.Anterior fascicle:
 1)Afferent: frontal spinothalamic tract-conscious reaction onto tactile
irritation.
 2)Efferent:
 A)Frontal pyramidal tract;
 B)From midbrain(hearing and vision centers);
 C)From vestibular nuclei and reticular formation.

82. The cerebellum
Functions:

83. Cerebellum
 Functions:
 1.Reflectory(automatic)coordination of movements and regulation of the tone of
muscles.
 2.Participation in integrative processes providing organization of perception,
attention, speech, memory(long durating).

84. Structure
 Consists of 2 hemispheres, vermis. Surface forms narrow gyrus, separated by the
grooves, it increases its surface.
 The grey matter is present by the cortex covering all the surface of gyrus and by
subcortical nuclei-serratus and other.
 The white matter appears like narrow stratums forming bunches and bundles in
the middle part of cerebellum.

86. Fibers in composition of cerebellum:
1.Mossy-forming olivo-cerebellar, ponso-cerebellar
pathways.
2.Climbing-forming spino-cerebellar, olivo-cerebellar
pathways.
Peduncles of the cerebellum-they are continuities of
the white matter helping in connection of neighboring
departments of the brain. They are pathways: inferior,
middle, superior.

87. 1.Inferior:
A.towards the cortex of the cerebellum: dorsal spino-cerebellar,
olivo-cerebellar , vestibulo-cerebellar tract.
B.From the nuclei of cerebellum: to 1) n.olivae; to 2)
n.vestibular.
2.Middle:cortico-cerebellar tract(from nuclei of pons).
3.Superior:
A.Towards cortex of the cerebellum:-anterior spino-cerebellar
tract;
B.From nuclei of cerebellum to the midbrain.

88. The cortex of the cerebellum:
Consists of 3 layers:
1.Molecular layer: basket and stellate
neurons.
2.Ganglionic layer: Purkinje cells arranged in
1 layer.
3.Granular layer: granular cells.

93. 1.Molecular layer:
 1.1.Basket cells:
 1)Dendrites are branched in Molecular layer;
 2)Axon runs across the gyrus and gives collaterals to piriformis cells. Collaterals
form axo-somatic synapses-‘baskets’(cause inhibition of piriformis cells)

94. 1.2.Large stellate cells:
 1)Dendrites are branched in molecular layer;
 2)Axon is in composition of ‘baskets’
 Dendrites are thin. Axon is un-myelinated, going transversely
to make synapses with the dendrites of Purkinje cells.

95. 1.2.Small stellate cells:
 1)Dendrites and
 2)Axon form synapses with dendrites of piriformis cells.
 Inhibitory neurons.

96.  Basket cell has small perikaryon, numerous branching dendrites ascending
towards the surface of cerebellum. Un-myelinated axon runs horizontally, along its
course it gives off many descending branches forming basket-like terminal
arborization.

97. Ganglionic layer
 Piriformis cells(Purkinje):
 1)Dendrites are branched in molecular layer in 1 plane, perpendicular to the
surface of the gyrus.
 2)Axon runs to white matter, is terminated on nuclei of cerebellum. On the
level of Granular layer gives collaterals to the neighboring cells.

98.  Cells are large, multipolar. Have massive flask-shaped perikarya, arranged
as a single row along the outer edge of the granular layer.
 Contain a vesicular nuclei with prominent nucleolus. The dendritic tree
arise from the apex as 2-3 large dendrites enetring the molecular layer
and branching repeatedly with formation of fan-shaped arborization. The
axon arises from the base, acquires a myelin sheath, entering the white
matter. Most of axons are terminated in deep cerebellar nuclei.
 INHIBITORY cells.

99. 3.Granular layer:
 Cells: 1. Granular
 1)Dendrites are branched and form synapses on Mossy fibers.
 2)Axon is divided in Molecular layer in T-shape, runs parallel the gyrus and form
synapses with dendrites of piriformis cells.
 Irritated cells.
 The granular layer appears to be composed of closely packed nuclei which stain
deeply basophilic.

100. 2.Neuron Golgi II with short axons
(large stellate)
 1)Dendrites form synapses with axons of granular cells in Molecular layer.
 2)Axon forms synapses on dendrites of granular cells .
 Complex of synapses on Mossy fibers is called “Glomeruli of cerebellum”.

101. 3.Neurons Golgi I with long axon
 1)Dendrites are branched in granular layer;
 2)Axon runs to the white matter.


102. 4.Fusiform horizontal cells
 1)Dendrites are branched in granular layer;
 2)Axon runs to the white matter.

103. 1 Purkinje cell: 1600 granular cells
3 basket cells
5 stellate cells
0,3 Golgi neurons.
Afferent fibers are Climbing: form
synapses with Purkinje cells;
Mossy form synapses with granular cells.
Efferent fibers are axons of Purkinje cells,
terminated on subcortical nuclei.

104. Cortex of the brain
1.Surface:
Hemispheres of the brain have numerous folds and convolutions which
greatly increase square of the surface up to 3 times. Upper layer is present
by grey mater-cortex of the hemispheres. The thickness is 2-5 mm.

105. 2.Composition of the cortex:
a)Neurons of 3 types-pyramidal(85%), stellate(irritative) and
inhibitory(several types);
b)Glial cells-astroglial and microglial.
c)Nerve fibers with envelope made up of oligodendrocytes.
Cytoarchitectonic of the brain-method of distribution of neurons.
Myeloarchitectonic of the brain-method of distribution of fibers.

106. Neurons

107. 3.Layers of the cortex:
I.Molecular layer(surface):there are very less of neurons, mainly small in size
inhibitory cells. Large number of nerve fibers coming from underlying cells,
they connect neurons of different departments. Direction of these is parallel
to the surface.

108. II.External granular layer:
Number of neurons is higher than in I layer. All cells are small in size which
give granular appearance.
Composition of neurons:
a)Small pyramidal cells;
b)Stellate cells;
C)Inhibitory cells of several types.

109. III.Pyramidal layer of middle in size pyramids:
There are middle in size neurons and small number of inhibitory neurons.
Number of cells is less than in neighboring layers.
IV.Internal granular layer:
Basic type of cells are stellate.
There are also many horizontal myelinated nerve fibers forming intercortical
connections.

110. V.Ganglionic layer(layer of large pyramids):
Main content is present by large pyramidal cells, and giant pyramids(cells of
Betz) in anterior central convolution. There is also small number of inhibitory
neurons.
Axons of Betz’ cells form pyramidal pathways coming to motorneurons of
spinal cord. Axons of other pyramidal cells enter the white mater and then to
other regions of the cortex. So, there are mainly vertically oriented fibers.

111. VI.Layer of multiform cells:
Lies on the white mater. It is present mainly by small pyramidal cells(in upper
part) and inhibitory neurons of several types.
Concentration of neurons is reduced up to lower region of this layer.
Vertically oriented nerve fibers coming through out layer(from pyramidal cells
to white mater)

113. Pyramidal neurons
1.Shape and orientation:
I.The perikaryon has pyramidal shape.
II.The apex is always looking to the surface of the cortex and the basis-to the
white mater.
III.Among several dendrites one is the strongest coming from its apex.
IV.Axon is coming from the basis down(in to white mater) or up to the surface
of the cortex.

116. Functions of the pyramidal neurons
1.Axons of giant pyramidal neurons form so-called pyramidal pathways
coming to anterior horns of the spinal cord. They give many collaterals:
1)Inhibitory are coming to neurons of other regions of the cortex.
2)excitatory and inhibitory are to subcortical nuclei and nuclei of the trunk of
the brain.

117. 2.Axons of large, middle, small pyramidal neurons connect some regions of
the brain in its own hemisphere(associative) or in other(commissural).
So, they are the single neurons which axons leave cortex forming efferent
pathways.

118. Stellate neurons
1.Small in size, give granular appearance. They receive signals from afferent
nerve fibers.
2.As a response they excite other neurons of the cortex like pyramidal
neurons.
According to functions of stellate neurons the highest content of them is in
sensory centers. This type of cortex is called granular.
In motor centers(anterior central convolution)granular layers(II,IV) are not
developed well – this type is called agranular

119. Inhibitory neurons
1.Neurons with axoaxonic penicillus forming inhibitory synapses on afferent
fibers and limit entering signals.
2.Basket neurons forming inhibitory synapses on the cellbodies of pyramidal
neurons and correct their response.
3.Axoaxonic neurons forming inhibitory synapses on axons of pyramidal
neurons.
4.Neurons with double composition of dendrites. They block almost all types
of inhibitory neurons and unbrake pyramidal neurons.

120. Glial neurons
1.Astroglial cells as protoplasmic gliocytes with short and thick processes
which surround haemocapillaries an form haematoencephalic barrier. Other
functions are supporting, trophic, regulatory, metabolic.
2.Microglial cells are small with branched processes developed from
monocytes of the blood able for phagocytosis.
3.Oligodendroglial cells forming envelope of nerve fibers.

123. Nerve fibers
1.Associative-connect different regions of the same hemisphere.
2.Comissural-connect cortex of different hemispheres.
3.Projection-connect cortex and underlying departments of CNS.
Orientation is mainly vertical(perpendicular to the surface), but there are
also horizontal collaterals. So, signal is generalizing.

124. Modules of the brain
All elements of the cortex are organized in so-called modules.
Each module is cylindrical in shape column, oriented perpendicular to the
surface of the cortex and distributed through out all thickness of the cortex.
Connecting elements are afferent fibers:
1)corticocortical is in the center of the module;
2)Two thalamocortical.
All other elements are grouped around them.

125. Age-related changes
1.In newborn in some frontal and temporal convolutions there are no myelin
sheaths, they are formed later.
2.In childhood there is gradual growing up of nerve fibers and glial cells.
3.With age gradual reducing of the number of neurons occurs. It is more
intense in old age. First dying cells are giant pyramids and Purkinje cells. Dye
is due to apoptosis(transgression of blood supplying, intoxication, stress,
loading by
lipofuscin.