nervous system by Dr. Mullapudi Ramakrishna

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.

67. 67

68. 68

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.

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 from sensory neurons of spinal
ganglia and it to motorneurons of adjacent nuclei.

81. 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.

85. The cerebellum
Functions:

89. 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.

90. 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.

91. 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.

106. 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.