Intro to nervous system David Kachlík a Petr Zach.

Intro to

nervous system

David Kachlíka

Petr Zach

Nervous tissue cells parcellationNervous tissue cells parcellation

Two types of cells:• neurons – cells transmitting informations• Glial cells (neuroglia, glia) (neuroglia) –

neuronal support, protection and participation in their nutrition and work– astrocytes (astrocytus)– oligodendrocytes (oligodendrocytus)– microglia (microgliocytus)– ependymal cells (ependymocytus)

NervesNerves• Are formed by clusters of nervous fibers• Nerve fibers have covering similarly to muscular

tissue:– endoneurium

• Layer of reticular fibers around individual nerve fibers

– perineurium• „sleeve“ containing bundles of nerve fibers formed by

layers of epiteloid cells• Numerous zonulae occludentes – non-passable

barrier shielding nerve fibers

– epineurium• Fibrous covering of whole nerve

NervesNerves

GangliasGanglias• Nerve ganglias are accumulation of pericaryons in PNS• They have ovoid shape and their surface is covered by

capsule from thick non-organized fibrous tissue• Typical are satellite cells (gliocyti ganglionici) – small

cuboid cells surrounding perikarya of neurons

http://en.wikipedia.org/wiki/Dorsal_root_ganglion http://www.pharmainfo.net/introduction-autonomic-nervous-system/classification

Ganglias - dichotomizationGanglias - dichotomization

• Spinal ganglia (ganglion spinale)– sensory (ganglion sensorium)

– In posteroir roots of spinal nerves and in the course of cranial nerves (V, IX, X)

– Contain typical pseudounipolar neurons

– Carry sensory impulses from periphery into CNS

• autonomous (vegetative) ganglias (ganglion autonomicum)– In the course of autonomic nerves

– Contain multipolar neurons

– Layer of satellite cells is incomplete

– Intramural ganglias• Parasympatetic ganglias in the wall of hollow organs

Development of neural tubeDevelopment of neural tube

Nervous tissue develops from neuroectoderm

• Neuroectoderm originates from ectoderm by notochord induction

neural plate in the neurulation process creates neural tube=foundation of CNS

• Remnant of neuroectoderm separates neural crest (crista neuralis) = foundation of PNS and other structures (ectomezenchyme of the head etc.)

Development of neural tubeDevelopment of neural tube

• Primary neurulation– Separates ectoderm into three cell types

• Inside oriented neural tube• epidermis externally• Cells of neural crest

• Secondary neurulation – Cells of neural plate create chorda dorsalis

• In the course of 35th somite formation

Development of neural tubeDevelopment of neural tubeEpitelium of neural tube soon changes into multi layer

neuroepitelium in which are created 3 layers:• internal (germinal) zone (zona ventricularis; matrix

germinalis)– Until half of intrauterine life fast proliferating (origination of

neuroblasts)– Then reduction into ependyme

• Middle (shell) zone (zona intermedia; zona pallii)– Formed mostly by migrating neuroblasts– Grey matter originates from it

• External (marginal) zone (zona marginalis)– Formed by extenstions of neuroblasts– White matter originates from it

Development of neural tubeDevelopment of neural tube

Somite (Somite (somitussomitus))• somitomers around 3rd week• At the end of 5th week 42-44 somites

http://www.aps.uoguelph.ca/~swatland/HTML10234/LEC5/LEC5.html

http://www.uprightape.net/Image_Pages/UA_Fig7-4_SomiteDevel.html

MyotomeMyotome

• Central part of primitive segment

• Starting 4th week during differentiation it retains lastly epiteloid organization

• Foundation of skeletal muscles

SclerotomeSclerotome

• Dorzomedial part of primitive segment

• At the 4th week gains chars of mesenchyme

• Getting thicker around chorda dorsalis

• Creates foundation of axial skeleton (vertebras, costas, sternum) and base of skull

• Ventrolateral part of primitive segment

• During differentiation from start of 4th week of development gains mesenchyme char

• Migrates into somatopleura• Give foundation to fibrous

part of skin (dermis and tela subcutanea)

• Parts originating from the same dermatome have nerve supply from one spinal root

DermatomeDermatome

Composition of brain tissueComposition of brain tissue• Grey matter (substantia grisea)

– pericarya of neurons, mostly non myelinated nerve fibers

– Protoplazmic astrocytes, oligodendrocytes and microglia

• White matter (substantia alba)– Mostly myelinated fibers– Fibrilary astrocytes, oligodendrocytes and

microglia

http://library.med.utah.edu/WebPath/HISTHTML/NEURANAT/CNS230A.htmlhttp://fuckyeahnervoussystem.tumblr.com/post/1276369326/spinal-cord-light-micrograph-of-a-cross-section

CNS description- partsCNS description- parts

• Spinal cord (Medulla spinalis)• Brain stem (Truncus encephali)

– Oblongate (Medulla oblongata)– Pons (Pons) – formerly pons Varoli– Midbrain (Mesencephalon)

• Small brain (Cerebellum)• Diencephalon (Diencephalon)• Forebrain (Telencephalon)

– Basal ganglia (nuclei basales)– Brain cortex (cortex cerebri)

Telencephalon

Diencephalon

Mesencephalon

Pons

Medulla oblongata

Medulla spinalis

Cerebellum

CNS descriptionCNS description• Inside CNS cavities

– 4th ventricle, 3rd ventricle and two lateral ventricles

• CNS covered by meninges:– Hard meninge (pachymeninx = dura mater)– Soft meninge (leptomeninx)

• arachnoid (arachnoidea mater)• pia (pia mater)

• Inside ventricles is cerebrospinal fluid (liquor cerebrospinalis = CSF)

http://faculty.irsc.edu/FACULTY/TFischer/AP1/AP%201%20resources.htm

http://mortdev.blogspot.cz/2008/09/brain-autopsy.html

CNS functionsCNS functions• Spinal cord – reflexes, ascending and

descending tracts• Brain stem – vitally important reflexes

(respiratory, cardiovascular, vomiting, coughing, synchronization of eyeball movement)

• diencephalon – hormonal production, circadian rhytms, termoregulation, food intake, autonomic regulation

• Terminal brain– cortex: functional cortical areas– Basal ganglia: movement patterns

• limbic system – behavior, emotions, memory

Brain stemBrain stem

• Converting all ascending and descending nerve tracts (tractus)

• Reticular formation (RF; formatio reticularis)– Vital reflex centers

• Cardiac activity, respiration, vazomotorics, consciousness

• Nuclei of cranial nerves– n. III - XII

Mesencephalon

Pons

Medulla oblongata

Medulla spinalis

Truncus encephali• Medulla oblongata = oblongate• Pons (Varoli) = pons• Mesencephalon = mid brain

Cavities of brain stem• ventriculus quartus = 4th ventricle

– fossa rhomboidea = bottom of 4th ventricle

• aqueductus mesencephali (Sylvii) = for CSF between 3rd and 4th ventricle

Brain stem - Brain stem - compositioncomposition

Medulla oblongataMedulla oblongata

Ventral side:• pyramis

– Fibers of tractus corticospinalis

• oliva

dorsal side:• tuberculum gracile

+ cuneatum

Mesencephalon = Mesencephalon = Mid brainMid brain

• Cranial part of brain stem (2 cm)

Ventral side:• fossa

interpeduncularis (intercruralis) – Exit of n. III

• crura cerebri– Descending motor

systems (tractus pyramidalis)

• fibrae corticospinales• other

Dorzal side:

lamina quadrigemina = lamina tecti

• colliculi superiores– vision

• colliculi inferiores– hearing

• Exit of n. IV

Mesencephalon = Mesencephalon = Mid brainMid brain

Mesencephalon = mid brainMesencephalon = mid brain

Internal structure: 3 parts on section• tectum mesencephali (mesencephalic tectum)

= dorzal thin plate with two pairs of tubers

- aqueductus mesencephali Sylvii

• pedunculus cerebri (brain pedicle)

= ventral most of midbrain– tegmentum mesencephali

• nucleus ruber – motor nucleus of stem• substantia nigra – motor nucleus – basal ganglion• Ascending and descending tracts

– crus cerebri – contains only descending tracts

RFRF

Formatio reticularisFormatio reticularis (reticular formation) RF (reticular formation) RF

• Fylogenetically oldest part of brain• Maintains basic stereotypes (walk, sleep)• Influences wake, tiredness and motivation• Morphologically ill defined• Centrall and dorsally in brain stem,

especially in the pons• Ascending activation systém → talamus,

hypotalamus, cortex• Descending inhibitory systém →

cerebellum, sensory nerves

RF functionRF function• Seat of reflexes

– nutrition– self defense

• respiratory• pneumotactic center• vazomotor center• center for heart beat rate regulation• center for vomiting• Pain• Body temperature maintenance

Cerebellum

Cerebellum = small brainCerebellum = small brain

• vermis (worm) – midline non paired• hemispheria (cerebellar hemispheres) – paired• cortex x corpus medullare• 3 lobes

– lobus anterior– lobus posterior– lobus flocculonodularis

• 4 nuclei cerebelli (small brain nuclei)– nucleus dentatus– nucleus emboliformis– nucleus globosus– nucleus fastigii

Cerebellum – posterior viewCerebellum – posterior view

VERMIS

Cerebellum – three pediclesCerebellum – three pedicles

• pedunculus cerebellaris inferior = corpus restiforme + juxtarestiforme

• pedunculus cerebellaris medius= brachium pontis

• pedunculus cerebellaris superior= brachium conjunctivum

Cerebellum – ventral viewCerebellum – ventral view

P.C.MEDIUS

P.C.SUPERIOR

P.C.INFERIOR

DiencephalonDiencephalon

• thalamus

• metathalamus

• subthalamus

• hypothalalmus

• epithalamus

• thalamus opticus

Thalamus Thalamus (thalamus dorsalis)(thalamus dorsalis)

• „brain secretary“ all except for smell• Nuclei parcellated according to position

or connection– nuclei anteriores, dorsales, intralaminares,

mediani, mediales, posteriores, ventrales, reticularis

– specific • ncl. ventralis posterolateralis, posteromedialis (VPL,

VPM) – hmat, bolest, proprioception• ncl. ventralis anterior, lateralis (VA, VL) - motoric

– Non specific nuclei - (? function)– Association nuclei

Parcellation of thalamic nuclei Parcellation of thalamic nuclei according to positionaccording to position

nucleinuclei anteriores, dorsales, anteriores, dorsales, intralaminares, mediani, mediales, intralaminares, mediani, mediales, posteriores, ventrales, reticularisposteriores, ventrales, reticularis

MetathalamusMetathalamus• Lateral geniculate body (corpus geniculatum

laterale) – vision center• Medial geniculate body (corpus geniculatum

mediale) – hearing center

SubthalamusSubthalamus

• zona incerta= unsure region)– Function similar to

ncll. reticulares thalami

– Making difference of other impulses that regularly enter into talamus

• nucleus subthalamicus= corpus Luysi– Connected with basal

ganglia

HypothalamusHypothalamus

Highest autonomic center• nuclei x transversal and longitudinal zones• Crossing of optic nerve (chiasma opticum)• hypophysis• Mammillary bodies (corpora mamillaria)

HypothalamusHypothalamus

Hypothalamus – fyziologyHypothalamus – fyziology

Hormones (blood), nerves, CSF

HYPOTHALAMUS

Endocrine + autonomic system

HOMEOSTASIS emotions (= LIMBIC SYSTEM)

Telencephalon = CerebrumTelencephalon = Cerebrum

• Pallium (pars pallialis; pallium) cerebrum (= hemispheres)

• Basal part (pars basilaris) nuclei basales = bazal ganglias

• Septal part (pars septalis) septum

PalliumPallium

• Paired hemispheres (hemishperia)

• 5 lobes (lobi)– frontal (lobus frontalis)– parietal (lobus parietalis)– occipital (lobus occipitalis)– temporal (lobus temporalis)– insular (lobus insularis) =

inzula

• gyr) x sulci – basic description unit

Cortical parcellationCortical parcellation (Areae Brodmanni) (Areae Brodmanni)

• primary – for one modality

• association– secondary– terciary

• example:– area 4 – primary motoric– area 17 – primary visual– area 18,19 – association visual

bazal ganglia; bazal ganglia; nuclei basalesnuclei basales

• Striated body (corpus striatum)– Caudate nucleus (nucleus caudatus)– putamen

• globus pallidus

• substantia nigra – in mid brain

• ncl. subthalamicus – in diencephalon

Basic function: motor patterns formation

Limbic systemLimbic system

• „visceral brain“• Around brain stem (= “collar“)• emotions, memory, smell• Connected with emotional reactions, sexual

behavior and offspring care, social behavior, memory and regulation of many autonomic function

• Cortical and subcortical parts• hippocampus• corpus amygdaloideum = amygdala• other