INTRODUCTION TO STUDY OF ANATOMY

OF CNS:

* Principles of morphological and functional

organization of the nervous system

* Anatomy of the spinal cord

NERVOUS SYSTEM: CENTRAL (CNS) AND PERIPHERAL (PNS) PARTS.

Embryo development (transverse section)

Early stages of development of the human nervous system. Nerve tube formationA - the nerve plate;B - the nerve groove;C - the neural tube;1 - ectoderm;2 - mesoderm;3 - endoderm;4 - chord;5 - ganglionic plate;6 - mesenchyme;7 - the neural tube;8 - nerve groove;9 - a nerve cushion;10 - neural plate.

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Principles of the organization of the nervous system.

1. Reflexity.

2. Centralization.

3. Cephalization.

4. Corticolization of functions.

5. Subordination.

Cellular components of CNS on the histological section

CELL COMPONENTS of CNSNeurons regarded as SFU in the NS

MACROGLIA: related cells that perform the function of the stroma of other organs in the central nervous system: a soft skeleton (support), trophies, barriers, ensuring the functioning of neurons .

Astrocytic, ependymicglia and oligodendroglia

MICROGLIA - vascular macrophages

The myelin sheath of axons - provides high speed of nervous excitement

Synapse: the main mechanism of interneuron communication, transmission of excitation. Operates with participation of mediator

MORPHOLOGICAL TYPES OF NEURONSNeuron: the body of the neuron (pericarion)

DendritesAxon

bipolar unipolar

Pseudo-unipolar multipolar

Morpho-functional types of neurons

1. Sensitive

2. Motor

- somatic

- visceral

3. Associative

(4. Neurosecretory cells)

MAIN MORPHOFUNCTIONAL TYPES OF NEURONS

Sensory or sensitive or afferent * shape - pseudounipolar or bipolar

feature - existance of receptor "translator" of stimulus energy into the language of the central nervous system, into nervous excitation (nerve impulses)

location of the pericaria (body) - outside the central nervous system, in the sensory ganglia of the spinal nerves ( spinal ganglia) a. cranial nerves

role - perception of stimuli, codation of information in nervous impulses, primary analysis, conduction of impulses in a specific direction

Symptomes of the neuron lesion: loss of one or another type of sensitivity in the receptor site depending on its specialization - anesthesia in corresponding area ( lack certain kind of senses)

Types of receptors - peripheral components of sensitive neurons

MAIN MORPHOFUNCTIONAL TYPES OF NEURONS

MOTOR somatic :

shape - multipolar feature - presence of neuromuscular junctions location of the pericaria Body- inside the CNS, in the

motor nuclei of the spinal ( anterior horns) a. cranial nerves within the spinal cord and brain stem

The only type of neurons that transmit the "command" to the striated muscles (the principle of the common terminal pathway in the CNS)

Neuron lesion: peripheral (flaccid) paralysis of the innervated muscle fibers:(lack of movements, of reflexes, of tone: three A –

atony

Areflexy

atrophy

peripheral paralysis

MAIN MORPHOFUNCTIONAL TYPES OF NEURONS

ASSOCIATIVE:

shape - multipolar

feature - about 95 % of all the neurons inside the CNS

location of the pericaria body- inside the CNS(except for the intestinal NS), in the sensory a. autonomic (vegetative) nuclei of the spinal a. cranial nerves, in all the suprasegmental centers

role - depot of individual experience (memory), analysis, choice of the most rational program of action

symptoms of the damage - variable in dependence upon the composed center

NERVOUS CENTER (morphologically, clinically) is a group of the same type of neurons with a common history, functions and connections and the obligatory presence of synapses

SEGMENTARY CENTERS

• HAVE DIRECT CONNECTION WITH THE PERIPHERAL NERVOUS SYSTEM, WITH INNERVIBLE PERIPHERY

• PRESENTED BY THE NUCLEI OF SPINAL AND CRANIAL NERVES

• EXISTS ONLY IN THE SPINAL CORD AND BRAIN STEM

• WITH THEIR DAMAGE, REPORTING SYMPTOMS ARE IN THE STRONGLY DEFINED REGION

NEURAL ENSEMBLES - NERVOUS CENTERS

NUCLEUS of NERVE is a group of similar neurons with which the nerve begins or ends

TYPES OF NUCLEUS OF NERVES (segmental centers):

SENSITIVE NUCLEUS OF NERVES

Contain the bodies of associative neurons, which are the first in the CNS to receive information from the periphery through the corresponding nerve

EXISTS ONLY IN THE COMPOSITION OF THE SPINAL CORD AND THE BRAIN STEM

WITH THEIR DAMAGE: anesthesia (loss of sensitivity of a certain type depending on the nature of the nucleus) in the area of action of this nerve

NUCLEI OF NERVES as SEGMENTAL CENTERS

Dermatome

MOTOR NUCLEI OF NERVES

They contain the bodies of motor somatic neurons, the axons of which form the motor portion of the nerve

Defeat of the motor nucleus: peripheral (flaccid) paralysis of muscles innervated by this nerve (muscle group):

atony

Areflexy

atrophy

Motor nuclei C5 - C8: ............... .. what is paralyzed?

Motor nucleus V: ........................... what is paralyzed?

Motor nuclei VII: ......................... What is paralyzed?

Peripheral paralysis of the muscles of the lower limb - where the focus in the central nervous system ?

NUCLEI OF NERVES as SEGMENTAL CENTERS

SUPRASEGMENTAL CENTERS

DO NOT HAVE ANY DIRECT COMMUNICATION WITH THE INNERVIBLE PERIPHERY, WORK ONLY THROUGH SEGMENTAL CENTERS OR INTERACTING WITH EACH OTHER

PRESENTED IN THE BRAIN STEM and in upper parts of the brain

WITH THEIR lesion no Distinct SYMPTOMS (PARALYSIS, ANESTHESIA), PERCEPTION AND MOTOR REACTIONS are preserved, their quality varies (exception is a number of centers of the cortex of the cerebral hemispheres)

NEURAL ENSEMBLES - NERVOUS CENTERS -II

NUCLEUS of spinal nerves (main): SENSITIVE: n. Proprius, n. Thoracicus, n. Intermediomedialis (differences - kind of sensitivity) MOTOR: medial (ventro- and dorso-), lateral (ventro- and dorso-) (differences - area of innervation) VEGETATIVE (AUTONOMOUS): n. Intermediolateralis(to be studied later)

Nuclei of cranial nerves - in the brain stem

Suprasegmental centers in the brainstem

Suprasegmental centers in the brain

SPINAL CORD

Segment of the spinal cord.

Segments of the spinal cord.

Рис 15 . Сегмент спинного мозга

A spinal cord segment = a portion of spinal cord that gives rise to a pair (right & left) of spinal nerves.

A spinal cord segment is a section of the spinal cord corresponding to two pairs of roots or to a pair (right & left) of spinal nerves

and having its own innervation zone

TRANSVERSE SECTION OF THE SPINAL CORD

main components of the grey a. white matter (horns, funiculi)

main details of the external aspect (fissure)

Inner organization - horns and their nuclei, the nature and connections

-posterior horn: sensory nuclei, association neurons :

# n. proprius ( pain, temperature, tactility)

# n. thoracicus ( proprioceptive)

# n. intermediomedialis ( proprioceptive)

lateral horn: substantia intermediolateralis ( autonomic)

anterior horn: motor nuclei ( medials - trunk; laterals - limbs

Topography of spinal cord segments, spinal nerves,cervicaland lumbo-sacral enlargements

Fetal 3rd month: ends at coccyx

Birth: ends at L3 during childhood

Adult position at approx L1-2

End: conus medullaris This tapers into filum terminale of

connective tissue, tethered to coccyx

Spinal cord segments are superior to where their corresponding spinal nerves emerge through intervetebral foramina

Denticulate ligaments: lateral shelves of pia mater anchoring to dura mater

Spinal cord

http://www.apparelyzed.com/spinalcord.html

Cauda equina

Meninges of the spinal cord

Spinal dura mater

Arachnoid mater

Pia (vascular) mater

Epidural space

Subdural space

Subarachnoid space

Meninges of the spinal cord

Spinal cord in vertebral canal