The structure of the spinal ganglion. Nervous system

DEVELOPMENT.

1. Neural tube - CNS - Gray and white in Vegetative

2. Neural crest - Peripheral. – Ganglia system

nervous nerves and

somatic nervous system

endings nervous s-ma

Table of derivatives and classification of the nervous system

In the process of development, the neural crest cells are distributed along the sides of the neural tube and, therefore, their further development proceeds in the lateral sections.

At the same time, neuroglial cells and sensitive pseudounipolar neurons, the spinal ganglion axons of which grow into the gray matter of the spinal cord, are released from the neural crest cells on the sides of the NT.

Part of the neural crest cells quickly moves deep into the body and is introduced into the wall of developing organs, or between them. These are the ganglia of the autonomic nervous system.

STRUCTURE OF GRAY AND WHITE MATTER

SPINAL CORD

The spinal cord consists of symmetrical halves. The gray matter is connected by gray adhesions, and the white matter is separated in front by a gap, and behind by a connective tissue septum.

The gray matter in the middle of the SM resembles the letter “H” and distinguishes in it: -

Dorsal - posterior

Lateral - lateral

Ventral - front horns.

In the center passes the spinal canal, filled with cerebrospinal fluid - cerebrospinal fluid. Its walls are lined with ependymocytes.

The gray matter consists of bodies of neurocytes surrounded by astrocytes and a dense network of their processes. The axons of neurocytes are barely covered with myelin, and the dendrites are without myelin.

Among the cells are:

Radicular - axons are part of the anterior root

Internal - processes are located within the spinal cord

Beam - image. beams of white matter and go up or down.

The bodies of these cells lie in groups and are called nuclei.

In the back horns(from the periphery to the center) distinguish between a spongy layer, a gelatinous substance, its own nucleus and a thoracic nucleus

All neurocytes of the posterior horns are associative in function.

In the spongy layer - small neurons and large gliocytes.

Gelatinous substance - neuroglia also predominates.

The nucleus proper lies in the center of the posterior horn. This is a cluster of bodies of large neurons, the axons of which cross over to the other side and rise up to the brain.

The cells of the thoracic nucleus are also large. Their axons go to the cerebellum in the white matter on the same side of the spinal cord.

In the area of lateral horns distinguish between the medial and lateral nuclei involved in the sympathetic division of the autonomic system. These are the associative neurons of the autonomic nervous system.

The cells of the medial nucleus transmit information to the cerebellum, and the cells of the lateral nucleus transmit information to the periphery as part of the anterior roots for innervation of the internal organs.

Anterior horns the widest and contain large cells from 100 to 140 microns, which lie in the form of five nuclei. These are motor neurons. Their processes form the anterior roots of the spinal cord, which control the skeletal muscles. Therefore, the nuclei are called motor.

There are medial and lateral groups of nuclei.

Medial - innerv. muscles of the back and trunk

Lateral - innerv. muscles of the limbs and therefore developed in the cervical and lumbar regions.

white matter- contains fibers and there are no tet neurocytes in it at all. Fibers are processes of cells, partially covered with a membrane. The processes are grouped into bundles according to function and therefore distinguish between bundles or pathways that carry information from sensory, motor or intercalary neurons. Sensory pathways are afferent pathways, motor pathways are efferent pathways. Examples: sensory pathways - gentle and wedge-shaped bundle of Flexig-Gowers; pyramidal path - motor - pyramidal path.

Outside, the white matter of the spinal cord is covered with a layer of collagen and elastic fibers and glychocytes. This is the pia mater. Many vessels from it penetrate into the spinal cord.

SPINAL GANGLION (sensory nodes)

This is a thickening along the posterior roots of the spinal cord.

The body is formed by a dense connective capsule, from which partitions with vessels extend inward.

The ganglion is an accumulation of pseudo-unipole sense bodies. neurocytes, which lie more on the periphery, closer to the vessels of the capsule.

The body of each neuron is surrounded by oligodendrocytes, which here are called mantle cells. As always, their functions:

Nutritious;

Protective

support

delimiting.

neurocytes- these are modified biopolar cells, the axons of which enter the spinal cord, forming its posterior roots. Their dendrites bring here information from receptors from the periphery.

Note that in supporting and protecting the peripheral nervous system, the connective tissue plays an active role compared to the CNS. This also applies to the connective tissue membranes of all peripheral nerves, which include:

Epineurium - outer shell;

Perineurium - separates bundles of fibers (ways);

Endoneurium - isolates separate processes.

The spinal cord and spinal ganglion, forming a chain of neurons, are responsible for the innate unconditioned reflexes of the body.

Somatic reflex arc

Three-neuron reflex arc-

This is a chain of three neurons:

Sensitive pseudounip.N.SG

Associate posterior horn SM

Engine n. front horn CM

Receptor - dendrite - body

Two-neuron somatic reflex arc is a chain of two neurocytes: feelings.

engine

From the previous description, exclude the intercalary neuron

Now remember the classic example, when touching a hot object, we withdraw our hand - this is an example of a somatic reflex arc, but look at this finger - it turned red, and this is already the work of the autonomic nervous system, it turns out that the sensitive neuron transmitted information to both the somatic and autonomic nervous system.

It can only be like this:

VEGETATIVE REFLECTOR ARC (sympathetic department)

Receptor – dendrite…..etc.

In the autonomic reflex arc, pre- and postganglionic fibers are distinguished. Pre is myelinated (white), and postganglionic is unmyelinated (gray).

vegetative ganglion

1) location of cells

2) multipolar cells

3) all 4 types (MYTH) (sympathetic)

This is an accumulation of neurocyte bodies, which, unlike the spinal ganglion, are multipolar and can be different in function - motor, associative, sensitive and secretory.

As part of the autonomic ganglion, there are:

According to Dogel: 1). double long-axon

2). equidistant sens.

3). equidistant ass.

Based on the presence of cells of different functions, the reflex arc can close within the ganglia themselves, without going beyond the boundaries of the autonomic nervous system, for which it received its name autonomous, independent.

THE PRINCIPAL STRUCTURE OF THE VEGETATIVE

NERVOUS SYSTEM.

Sympathetic department:

Associate nuclei of the lateral horns of the CM

Chains of pre- and paravertebral ganglia along the spine

Parasympathetic department:

Center - 3,7,9,10 craniocerebral n.

Peripheral. - intramural plexuses inside the organs - intrumur.ganglia.

private histology.

Private histology- the science of the microscopic structure and origin of organs. Each organ is made up of 4 tissues.

Organs of the nervous system.

On a functional basis

1. somatic nervous system- participates in the innervation of the human body and higher nervous activity.

a. Central department:

i. Spinal cord - nuclei of the posterior and anterior horns

ii. Brain - cerebellar cortex and cerebral hemispheres

b. Peripheral department:

i. spinal ganglia

ii. cranial ganglia

iii. nerve trunks

2. autonomic nervous system- provides the work of internal organs, innervates smooth myocytes and represents the secretory nerves.

1) sympathetic:

a. Central department:

i. Spinal cord - nuclei of the lateral horns of the thoraco-lumbar region

ii. brain - hypothalamus

b. Peripheral department:

i. Sympathetic ganglia

ii. nerve trunks

2) Parasympathetic:

a. Central department:

i. Spinal cord - nuclei of the lateral horns of the sacral region

ii. Brain - brainstem nuclei, hypothalamus

b. Peripheral department:

i. parasympathetic ganglia

ii. nerve trunks

iii. Spinal and cranial ganglia

Anatomically The organs of the nervous system are divided into:

1. Peripheral nervous system.

2. Central nervous system.

Embryonic sources of development:

1. neuroectoderm(gives rise to the parenchyma of organs).

2. mesenchyme(gives rise to the stroma of organs, a set of auxiliary structures that ensure the functioning of the parenchyma).

The organs of the nervous system function in relative isolation from the environment, separating from it. biological barriers. Types of biological barriers:

1. Hematoneural (delimits blood from neurons).

2. Liquoroneural (delimits cerebrospinal fluid from neurons).

3. Hematoliquor (delimits cerebrospinal fluid from blood).

Functions of the nervous system:

1. Regulation of the functions of individual internal organs.

2. Integration of internal organs into organ systems.

3. Ensuring the relationship of the organism with the external environment.

4. Ensuring higher nervous activity.

All functions are based on the principle reflex. The material basis is reflex arc, consisting of 3 links: afferent, associative and efferent. They are distributed to individual organs of the nervous system.

Organs of the peripheral nervous system:

1. Nerve trunks (nerves).

2. Nerve nodes (ganglia).

3. Nerve endings.

nerve trunks - these are bundles of nerve fibers, united by a system of connective tissue membranes. The nerve trunks are mixed, i.e. each has myelin and amyelin fibers, as a result of which the somatic and autonomic nervous systems are served.

The structure of the nerve trunk:

1. Parenchyma: unmyelinated and myelinated nerve fibers + microganglia.

2. Stroma: connective tissue membranes:

1) Perineurium(perineural sheaths: RVNST + blood vessels + ependymogliocytes + cerebrospinal fluid).

2) epineurium(PVNST + blood vessels).

3) Perineurium(cleavage from the epineurium into the trunk).

4) Endoneurium(RVNST + blood vessels).

There is a slit-like space in the perineurium - slit-like perineural sheath which is filled liquor(circulating biological fluid). Structural components of the walls of the perineural sheath:

1. Low-prismatic ependymogliocytes.

2. Basement membrane.

3. Subependymal plate.

4. Blood vessels.

Liquor in the perineural vagina may be absent. They are sometimes injected with anesthetics, antibiotics (because the disease spreads through them).

Functions of nerve trunks:

1. Conduction (conduct a nerve impulse).

2. Trophic (nutritional).

4. They are the initial link in the secretion and circulation of cerebrospinal fluid.

Regeneration of nerve trunks:

1. Physiological regeneration(very active restoration of membranes due to fibroblasts).

2. Reparative regeneration(that section of the nerve trunk is restored, the nerve fibers of which have not lost contact with the perikaryon - they are able to grow by 1 mm / day; peripheral segments of the nerve fibers are not restored).

Nerves (ganglia) - groups or cooperations of neurons, taken out of the brain. The nerve nodes are "dressed" in capsules.

Ganglia types:

1. Spinal.

2. cranial.

3. Vegetative.

spinal ganglia - thickenings on the initial sections of the posterior roots of the spinal cord; this is a cluster of afferent (sensitive) neurons (they are the first neurons in the reflex arc chain).

The structure of the spinal ganglion:

1. Stroma:

1) external connective tissue capsule, consisting of 2 sheets:

a. outer sheet (dense connective tissue - continuation of the epineurium of the spinal nerve)

b. inner sheet (multi-tissue: RVNST, gliocytes; analogue of the perineurium of the spinal nerve; there are splits that pass to the intraorgan septa, filled with cerebrospinal fluid).

2) intraorgan partitions extending from the capsule into the node

b. blood and lymph vessels

c. nerve fibers

d. nerve endings

3) own connective tissue capsules of pseudo-unipolar neurons

a. fibrous connective tissue

b. single layered squamous ependymoglial epithelium

c. perineuronal space with cerebrospinal fluid

2. Parenchyma:

1) the central part (myelinated nerve fibers - processes of pseudo-unipolar neurons)

2) peripheral part (pseudounipolar neurons + mantle gliocytes (oligodendrogliocytes)).

Functions of the spinal ganglion:

1. Participation in reflex activity (the first neurons in the reflex arc circuit).

2. They are the initial link in the processing of afferent information.

3. Barrier function (hematoneural barrier).

4. They are a link in the circulation of cerebrospinal fluid.

Sources of embryonic development of the spinal ganglion:

1. Ganglionic plate (gives rise to the elements of the parenchyma of the organ).

2. Mesenchyme (gives rise to the elements of the stroma of the organ).

Ganglia of the autonomic nervous system - located after the spinal cord, participate in the creation of autonomic arches.

Types of ganglia of the autonomic nervous system:

1. Sympathetic:

1) Paravertebral;

2) Prevertebral;

2. Parasympathetic:

1) Intraorganic (intramural);

2) Perioorganic (paraorganic);

3) Vegetative nodes of the head (along the cranial nerves).

The structure of the ganglia of the autonomic nervous system:

1. Stroma: the structure is similar to the stroma of the spinal ganglion.

2.1. Parenchyma of sympathetic ganglia: neurons located randomly throughout the ganglion + satellite cells + connective tissue capsule.

1) large long-axon multipolar efferent adrenergic neurons

2) small equidistant multipolar associative adrenergic intensely fluorescing (MIF) - neurons

3) preganglionic myelin cholinergic fibers (axons of neurons of the lateral horns of the spinal cord)

4) postganglionic non-myelinated adrenergic nerve fibers (axons of large ganglion neurons)

5) intraganglionic non-myelinated associative nerve fibers (axons of the MYTH - neurons).

2.2. Parenchyma of the parasympathetic ganglia:

1) long-axon multipolar efferent cholinergic neurons (Dogel type I).

2) long-dendritic multipolar afferent cholinergic neurons (Dogel type II): dendrite - to the receptor, axon - to types 1 and 3.

3) equidistant multipolar associative cholinergic neurons (Dogel type III).

4) preganglionic myelin cholinergic nerve fibers (axons of the lateral horns of the spinal cord).

5) postganglionic non-myelinated cholinergic nerve fibers (axons of type I Dogel neurons).

Functions of the ganglia of the autonomic nervous system:

1. sympathetic:

1) Conducting impulses to the working bodies (2.1.1)

2) Impulse propagation within the ganglion (braking effect) (2.1.2)

2. Parasympathetic:

1) Conducting an impulse to the working bodies (2.2.1)

2) Conducting an impulse from interoreceptors within local reflex arcs (2.2.2)

3) impulse propagation within or between ganglia (2.2.3).

Sources of embryonic development of the ganglia of the autonomic nervous system:

1. Ganglion plate (neurons and neuroglia).

2. Mesenchyme (connective tissue, blood vessels).

Spinal ganglion (g. spinale, PNA, BNA, JNA, LNH; synonym: G. intervertebral, G. spinal, spinal ganglion) is the common name for sensitive G. spinal nerves that lie in the corresponding intervertebral foramina and give fibers to the spinal nerves and back roots.

Big Medical Dictionary. 2000 .

See what "spinal ganglion" is in other dictionaries:

I Ganglion (Greek ganglion knot, tumor-like formation) cystic formation in the tissues adjacent to the tendon sheaths, articular capsules, less often to the periosteum or nerve trunks. The emergence of G. is associated with a constant mechanical ... ... Medical Encyclopedia

- (g. intervertebrale) see Spinal Ganglion ... Big Medical Dictionary

- (g. spinale) see Spinal Ganglion ... Big Medical Dictionary

Big Medical Dictionary

1. Any structure (in neurology, anatomy ed.), containing an accumulation of bodies of nerve cells, as well as a number of synapses. In the sympathetic nervous system, ganglion chains form sympathetic trunks (and nodes of large autonomic plexuses in the abdominal ... ... medical terms

GANGLION, KNOT- (ganglion, pl. ganglia) 1. Any structure (in neurology, anatomy ed.) containing an accumulation of nerve cell bodies, as well as a number of synapses. In the sympathetic nervous system, ganglion chains form sympathetic trunks (and nodes of large autonomic ... ... Explanatory Dictionary of Medicine

- (ganglion spinale) see Spinal Ganglion ... Medical Encyclopedia

Spinal cord- (medulla spinalis) (Fig. 254, 258, 260, 275) is a strand of brain tissue located in the spinal canal. Its length in an adult reaches 41 45 cm, and its width is 1 1.5 cm. The upper section of the spinal cord smoothly passes into ... ... Atlas of human anatomy

- (medulla spinalis), a phylogenetically ancient part of the central nervous system of vertebrates, located in the spinal canal. First appears in non-cranial (lancelet trunk brain), evolves in connection with the improvement of motor skills and the transition from ... ... Biological encyclopedic dictionary

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