Peripheral nervous system

Lection:

ANATOM.UA

PART 1

Ch. 1 Anatomia generalis

PART 2 – SYSTEMATA MUSCULOSKELETALIA

Ch. 2 Ossa

Ch. 3 Juncturae

Ch. 4 Musculi

PART 3 – SYSTEMATA VISCERALIA

Ch. 5 Systema digestorium

Ch. 6 Systema respiratorium

Ch. 7 Cavitas thoracis

Ch. 8 Systema urinarium

Ch. 9 Systemata genitalia

Ch. 10 Cavitas abdominopelvica

PART 4 – SYSTEMATA INTEGRANTIA I

Ch. 11 Glandulae endocrinae

Ch. 12 Systema cardiovasculare

Ch. 13 Organa lymphoidea

PART 5 – SYSTEMATA INTEGRANTIA II

Ch. 14 Systema nervosum

Ch. 15 Organa sensuum

Ch. 16 Integumentum commune

ANATOM.UA

https://fipat.library.dal.ca/ta2/

ANATOM.UA

The Spinal Cord

Foramen magnum to L1 or L2

Runs through the vertebral canal of the vertebral column

Functions

1. Sensory and motor innervation of entire body inferior to the head through the spinal nerves

2. Two-way conduction pathway between the body and the brain

3. Major center for reflexes

Fetal 3rd month: ends at coccyx

Birth: ends at L3

Adult position at approx L1-2 during childhood

End: conus medullaris

This tapers into filum terminaleof connective tissue, tethered to coccyx

Spinal cord segments are superior to where their corresponding spinal nerves emerge through intervetebral foramina (see also fig 17.5, p 288)

Denticulate ligaments: lateral shelves of pia mater anchoring to dura (meninges: more later)

Spinal cord

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

Spinal nerves

Part of the peripheral nervous system

31 pairs attach through dorsal and ventral nerve roots

Lie in intervertebral foramina

Spinal nerves continued

Divided based on vertebral locations

8 cervical

12 thoracic

5 lumbar

5 sacral

1 coccygeal

Cauda equina (“horse’s tail”): collection of nerve

roots at inferior end of vertebral canal

Spinal nerves continued

Note: cervical spinal nerves exit from

above the respective vertebra

Spinal nerve root 1 from above C1

Spinal nerve root 2 from between C1 and C2,

Clinically, for example when referring to

disc impingement, both levels of vertebra

mentioned, e.g. C6-7 disc impinging on

root 7

Symptoms usually indicate which levelMore about spinal nerves in the peripheral nervous system lecture

Protection:BoneMeningesCSF (cerebrospinal fluid)3 meninges:

dura mater (outer)arachnoid mater (middle)pia mater (inner)

3 potential spacesepidural: outside durasubdural: between dura &

arachnoidsubarachnoid: deep to arachnoid

Spinal cord coverings and spaces

LP (lumbar puncure) = spinal tap

(needle introduced into subdural space to collect CSF)

Lumbar spine needs

to be flexed so can go

between spinous

processes

Epidural space is external to duraAnesthestics are often injected into epidural spaceInjection into correct space is vital; mistakes can be lethal

Originally thought to be a narrowfluid-filled interval between the duraland arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of trauma or some ongoing pathologic process; in the healthy state, the arachnoid is attached to the dura and a naturally occurring subdural space is not present. http://cancerweb.ncl.ac.uk/cgi-bin/omd?subdural+space

Spinal cord anatomy Posterior median sulcus (“p”)

Anterior median fissure (“a”)

White matter (yellow here)

Gray matter (brown here)“p”

“a”

Gray/White in spinal cord Hollow central cavity (“central

canal”)

Gray matter surrounds cavity

White matter surrounds gray matter (white: ascending and descending tracts of axons)

“H” shaped on cross section

Dorsal half of “H”: cell bodies of interneurons

Ventral half of “H”: cell bodies ofmotor neurons

No cortex (as in brain)

Dorsal (posterior)

Ventral (anterior)

Central canal______

Spinal cord anatomy Gray commissure with central canal

Columns of gray running the length of the spinal cord

Posterior (dorsal) horns (cell bodies of interneurons)

Anterior (ventral) horns (cell bodies of motor neurons)

Lateral horns in thoracic and superior lumbar cord

White matter of the spinal cord(myelinated and unmyelinated axons) Ascending fibers: sensory information from sensory

neurons of body up to brain

Descending fibers: motor instructions from brain to spinal cord

Stimulates contraction of body’s muscles

Stimumulates secretion from body’s glands

Commissural fibers: white-matter fibers crossing from one side of cord to the other

Most pathways cross (or decussate) at some point

Most synapse two or three times along the way, e.g. in brain stem, thalamus or other

The Brain: embryonic

development Develops from neural tube

Brain subdivides into

Forebrain

Midbrain

Hindbrain

These further divide, each with a fluid filled region: ventricle, aqueduct or canal

Spinal cord also has a canal

Two major bends, or flexures, occur (midbrain and cervical)

Brain development Learn forebrain, midbrain and hindbrain in (b)

See next color coded pics in reference to (d)

Learn (e)

Encephalos means brain (otherwise you don’t need to learn “c”)

Space restrictions force cerebral hemispheres to grow posteriorly over rest of brain, enveloping it

Cerebral hemispheres grow into horseshoe shape (b and c)

Continued growth causes creases, folds and wrinkles

Anatomical classification Cerebral hemispheres

Diencephalon

Thalamus

Hypothalamus

Brain stem

Midbrain

Medulla

Cerebellum

Spinal cord

Parts of Brain

Cerebrum

Diencephalon

Brainstem

Cerebellum

Nervous System

Marieb 11.1

Martini 12-4

Comparison of Structural Classes of Neurons

Marieb T11.1.1

Saltatory Conduction

Marieb 11.16

Synaptic Cleft: Information Transfer

Marieb 11.18

Freeman 45-17a

• Brain

WHAT PARTS DO YOU KNOW THAT

ARE IN THE NERVOUS SYSTEM?

• Spinal Cord

• Peripheral Nerves

What makes up the brain, the spinal cord or

your peripheral nerves?

• Neurons are “the cell”

• Cell body

• Nucleus

• Axon

• Dendrite

• What do you think surrounds the cell?

• What other organelles would be needed?

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

How are neurons connected?

• Synapses!!

Why are neurons connected?

More neuron connections!

How does the Synapse carry the signal?

1. Electrical current travels down the axon

2. Vesicles with chemicals move toward the membrane - what is

that called?

3. Chemicals are released and diffuse toward the next cell’s

plasma membrane

4. The chemicals open up the transport proteins and allow the

signal to pass to the next cell - what type of diffusion is this?

There are lots of proteins and chemicals in your

body to do the work

Why is it important that it is an electrical current?

Are all neurons equal in size?• Brain vs spinal cord vs peripheral nerves?

About how many neurons are in the human brain? 100 billion

1 billion

around 15 feet

About how many neurons are in the spinal cord?

How long do you think the longest axon in the world is?

How many synapses

are in one neuron? 1,000 to 10,000!!

• Looking at the actual cells - how do they work?

• Looking at the connections - how and when do they work?

• Looking at what can change normal cells and connections

• Looking at diseases that occur in the brain

• One of the largest areas still unknown

• The you that is you is because of your neurons connecting!

What do you think can change

neurons and their connections?

• Accidents

• Drugs

• Alcohol

• Disease

Space Restriction and Brain Development

Marieb 12.3

Marieb 12.6ab

Ventricles of the Brain

Marieb 12.5

Functional Areas of the Cerebral Cortex

Marieb 12.8a

Functional Areas of the Cerebral Cortex

Marieb 12.8b

Primary Motor Cortex

Marieb 12.9.1

Sensory Areas

Marieb 12.8a

Association Areas

Marieb 12.8a

Tortora 14.12

Marieb 12.10ab

Diencephalon

Marieb 12.12

Meninges

Marieb 12.24a

1. Lateral ventricle

2. Interventricular foramen

3. Third ventricle

4. Cerebral aqueduct

5. Fourth ventricle

6a. Median aperture 6b. Lateral aperture 6c. Central canal (spinal cord)

7. Subarachnoid space

8. Arachnoid villi

9. Dural sinuses

Marieb 12.26b

Spinal Cord

Marieb 12.29a

Cross-Sectional Anatomy of the Spinal Cord

Anterior median fissure – separates anterior funiculi

Posterior median sulcus – divides posterior funiculi

Marieb 12.31a

Gray Matter and Spinal Roots

Marieb 12.31b

Gray Matter: Organization

Marieb 12.32

Structure of a Nerve

Marieb 13.3b

Cranial Nerves

Marieb 13.5a

Spinal Nerves

Marieb 13.6

Spinal Nerves: Roots

Marieb 13.7a

Marieb 13.7b

Martini 13-11

Freeman 45-20

Martini 16-10

Comparison of Somatic and Autonomic Systems

Marieb 14.2

The nervous system for topographicindication is divided into two divisions: thecentral nervous system (CNS) i peripheralnervous system (PNS).

Brain and spinal cord are related to the central nervous system (CNS).

Nerves, ganglia, nerve plexus and nerve endings are the peripheral nervous system (PNS).

Overview of the autonomic (vegetative) nervous system

For anatomical and functional

principle nervous system is divided

into two parts: the somatic nervous

system and autonomic nervous

system (ANS). The division of

somatic nervous system and

autonomic was proposed in the late

XVIII century by K.Bisha.

The somatic nervous system innervates the

soma (skin), skeletal muscles, joints. The

somatic nervous system of the body

provides a link with the environment.

The autonomic nervous system innervates

internal organs and coordinates their work.

Provides adaptive-trophic effects on the

whole body.

In the current international anatomical

nomenclature (Sao Paulo, 1997) instead of

the term VPS or autonomic nervous

system is proposed term "autonomous part

of the peripheral nervous system," but in

the national educational and scientific

literature on anatomy, physiology and also

in the clinic is common to use the term

"VNS ".

VNS is a part of the nervous system,

that conducts the functions of the

homeostasis regulation and getting

used to the environmental conditions

that Are constantly changing. VNS

innervates the visceral organs and

conducts the adapto- trophical

influence on the whole organism.

VNS for anatomical and functional

principle is divided into two parts: the

sympathetic part of ANS or sympathetic

nervous system and parasympathetic ANS

part or parasympathetic nervous system.

The term "parasympathetic nervous

system" was introduced in 1925 D.Lenhli.

In recent years, within the SPA is isolated

metasympatic nervous system (research

A.D.Nozdrachov, 1983)

Autonomic features or functions ofplant life (breathing, digestion, dis-multiplication, selection, etc.) areregulated by structure-roundsautonomic nervous system.

Dzh.Lenhli in 1889 divided theentire autonomic nervous systeminto two main divisions -parasympathetic andsympathetic. Separately, it hasbeen allocated so-called enteralsystem or intestinal plexus.

International anatomical nomenclature (SaoPaulo, 1997) offers not use the termautonomous (vegetative) nervous system toavoid many significance. Instead it wasproposed the term ‘autonomousdepartment’; autonomous part of theperipheral nervous system, divisioautonomica; pars autonomica systematisnervosi peripherici, which distinguishes thesympathic part, pars sympathica, and theparasympathetic part, pars parasympathica.

However, it should be noted, that inthe national scientific and educationalliterature, the term "autonomic nervoussystem" is more prevalent and thereforemore understandable. In addition, inrecent years due to research-A.D.Nozdracheva Jenny (1983, 1989)within the autonomic nervous system,probes offer quality local highlightanother part (system unit) -metasymphatic.

According to the modern definitionof autonomous (vegetative) nervoussystem - a part of the nervous systemthat serves as the regulating constancyof internal environment (homeostasis)and in-application of the terms of theNavier-former environment that isconstantly changing.

Regulation of homeostasis

includes the support for the body at

the right level of biochemical,

physical, chemical, and other

enzymatic constants, violation of

which is shown not only by

numerous vegetative, but also by

somatic dysfunction.

Regulation of homeokinesis includesproviding of various forms (mental,emotional, physical) and implementation ofbiological motivation of the whole organism.Violation of adequate homeokinetic reactionschanges behavior, contributesmaladjustment and eventually causes theemerge of mental illness or death of theorganism.

Nowadays the sympatheticautonomic (vegetative) nervoussystem is seen as a system alarm,mobilizing defenses and resourcesfor active interaction withenvironmental factors, i.e. asergotropic system.

Parasympathetic part, as well asmetasympathetic, was designed torestore and maintain homeostasis,disturbed as a result of the activity ofthe body, that carries trophotropicimpact. This metasympatheticautonomous (vegetative) nervoussystem implements this featureregionally (a separate organ or part).

The central segmental structures includeautonomic parasympathetic nucleus III, VII,IX, X pairs of cranial nerves, sacralparasympathetic neurons of the spinal cordand sympathetic neurons located in thelateral horns of the spinal cord in thethoraco-lumbar region. These centralsegmental centers (centers) are genuineautonomous centers because of theirfeatures and patterns of operation.

The most significant differences betweenthe morphological autonomous (vegetative)nervous system and the somatic nervoussystem are:

1) placing cells of the sympathetic andparasympathetic parts in certain places CNS(segmental centers);

2) the location of the second neuron axon andneuron bodies third simple reflex arcoutside the CNS.

Bodies of the third neuronsaccumulate as vegetative ganglions.That’s why the fibers of the autonomic(vegetative) nervous system, thatcarry impulses from the spinal cord orthe brain, are called preganglionarand the fibers that carry impulsesfrom the ganglion to the organ –postganglionar.

For the degree of distance from the centralnervous system and for topography vegetativenodes are divided into:

1) placed on either side of the spine nodes andqueues or paravertebral nodes (nodes sympathetictrunk);

2) placed in front spine units or second stageprevertebral units;

3) located nearby organs or tissues of the internalcomponents of phase III (respectively, extra- andintra-organ). Units I and II stage is sympathetic;Third stage units are predominantlyparasympathetic.

At the end of all preganglionic sympatheticand parasympathetic neurons, and interminals of the most postganglionicparasympathetic fibers releasedneurotransmitter acetylcholine. In addition,some postganglionic sympathetic fibers, thatinnervate sweat glands, are also broadcastvia acetylcholine.

Noradrenalin is aneurotransmitter inpostganglionic symphaticalendings.

A wide range of neuro-transmittersis typical for neurons of themetasymphatic part of theautonomous department ofperipheral nervous system, soamong them we can distinguishholinergetic, adrenergic,serotoninergetic, peptidergetic andother neurons.

In the organs with dual autonomicinnervation interaction functions ofsympathetic and parasympatheticnerves are observed in the form ofcaused effects antagonism.

For example, stimulation of sympatheticnerves causes the narrowing of pupils,inhibition of peristalsis, sphincter relaxation,expansion of the bronchi and coronaryarteries, strengthening and acceleration theheart rate. Irritation of parasympatheticnerves leads to constriction of the pupil,increased peristalsis, sphincter closure, thenarrowing of the bronchi and coronaryarteries to slowing down and weakeningheartbeat.

It should be emphasized that underthe conditions of autonomic and somaticbody functions as one integrated system,as sympathetic and parasympatheticnervous structures are widely used, sotheir functional synergy and antagonismare the two sides of the same process ofhomeostasis and homeokinesisregulation.

Parasympathetic part

of the autonomic

department of the

peripheral nervous

system.

Parasympathetic part ofautonomous department of theperipheral nervous system isrepresented by preganglionic fibers,going together with III, VII, IX and Xpairs of cranial nerves and pelvicvisceral nerves, parasympathetic nodes( among which are two types:

1) extraorganic;

2) 2) intraorganic, as well as relevantpostganglionic fibers.

Extraorganic parasympatheticcomponents are located near bodiesinnervated. These include 5 largeparasympathetic nodes of the head(Ciliary wing-palatine, submandibular,sublingual-headed, ear) andparasympathetic pelvic nodes.

Ciliar ganglion, g.ciliare,

has an uncertain shape and size (its

length in an average of 2 mm). This

node is located in the thickness of

fat tissue in the posterior part of the

eye socket on the outer surface of

the optic nerve.

Ciliary ganglion has three roots:

1) parasympathetic root, radix

parasympathica;

2) sympathetic root, radix

sympathica;

3) sensitive root, radix sensoria.

Postganglionic parasympatheticfibers of ciliary unit consist ofshort ciliary nerves, nn.ciliaresbrevis, are sent to the eyeball,penetrate the sclera andinnervate ciliary muscle and irissphincter muscle.

G.pterygopalatinum, near

to the size of 5 mm co-located in the pterygo-palatine fossa on the side of the pterygo-palatal opening.

Postganglionic parasympathetic fibers wing-palatal node providing secretory gland innervation of the mucosa of the nasal cavity, mouth, pharynx and lacrimal gland.

Pterygoplation ganglion has

three roots:

parasympathica;

sympathica;

Postganglionic parasympatheticfibers pterygo-palatal nodeprovides secretory glandinnervation of the mucosa in thenasal cavity, mouth, pharynxand lacrimal gland.

Submandibular node, g.submandibulare, of about 3 mm, lies on the submandibular salivary gland under n.lingualis.

Submandibular ganglion has

three roots:

parasympathica;

sympathica;

Postganglionic parasympatheticfibers submandibular nodeproviding secretory innervationsubmandibular and sublingualsalivary glands.

Sublingual node,g.sublinguale, sometimes is

placed on the lateral surface ofsublingual salivary glands, butmore often is a cluster ofneurons along the branchesn.lingualis to sublingual gland.

Sublingual ganglion has three

roots:

parasympathica;

sympathica;

Postganglionic parasympatheticfibers of the sublingual nodeprovide secretory innervationto the sublingual gland.

Ear node, g.oticum, of about 3 mm, located in the infratemporalfossa medially from the n.mandibularis under the oval hole.

Ear ganglion has three roots:

parasympathica;

2) sympathetic root, radix sympathica;

Postganglionic parasympathetic fibers ear unit provide the secretory innervation of the parotid salivary gland.

Pelvic nodes, gg.pelvica, are located in the lower part of hypogastric pelvic plexus and other vegetative plexus. Each has three roots:

1) ) parasympathetic root, radix

parasympathica;

2) sympathetic root, radix sympathica;

Nn.splanchnici pelvici come from the front of branches II-IV sacral nerves (most of them are preganglionic parasympathetic fibers, less - sensitive) and provide parasympathetic and sensitive innervation of the pelvic organs and intestinal tract below the descending colon.

The sympathetic part of the autonomous

department of the peripheral nervous

system

The sympathetic part of the autonomous department of the peripheral nervous system is represented by preganglionic and postganglionic fibers and paravertebral (nodes sympathetic trunk) and prevertebralsympathetic nodes.

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