Download Nerves

Intro
to
nervous system
David Kachlík
a
Petr Zach
Nervous 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)
Nerves
• 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
Nerves
Ganglias
• 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 - 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 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 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 tube
Epitelium 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)
Development of neural tube
Somite (somitus)
• 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
Myotome
• Central part of
primitive segment
• Starting 4th week
during differentiation it
retains lastly epiteloid
organization
• Foundation of skeletal
muscles
Sclerotome
• 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
Dermatome
• 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
Composition 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://fuckyeahnervoussystem.tumblr.com/post/1276369326/spinal-cord-light-micrograph-of-a-cross-section
http://library.med.utah.edu/WebPath/HISTHTML/NEURANAT/CNS230A.html
CNS 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 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)
http://faculty.irsc.edu/FACULTY/TFischer/AP1/AP%201%20resources.htm
• Inside ventricles is cerebrospinal fluid
http://mortdev.blogspot.cz/2008/09/brain-autopsy.html
CNS 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 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
Brain stem - composition
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
Medulla oblongata
Ventral side:
• pyramis
– Fibers of tractus
corticospinalis
• oliva
dorsal side:
• tuberculum
gracile +
cuneatum
Mesencephalon =
Mid 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
Mesencephalon =
Mid brain
Dorzal side:
lamina quadrigemina
= lamina tecti
• colliculi superiores
– vision
• colliculi inferiores
– hearing
• Exit of n. IV
Mesencephalon = 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
RF
Formatio reticularis
(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 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 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
Cerebellum – posterior view
VERMIS
Cerebellum – three pedicles
• pedunculus cerebellaris inferior
= corpus restiforme + juxtarestiforme
• pedunculus cerebellaris medius
= brachium pontis
• pedunculus cerebellaris superior
= brachium conjunctivum
Cerebellum – ventral view
P.C.SUPERIOR
P.C.MEDIUS
P.C.INFERIOR
Diencephalon
•
•
•
•
•
•
thalamus
metathalamus
subthalamus
hypothalalmus
epithalamus
thalamus opticus
Thalamus (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
according to position
nuclei anteriores, dorsales, intralaminares, mediani,
mediales, posteriores, ventrales, reticularis
Metathalamus
• Lateral geniculate body (corpus geniculatum
laterale) – vision center
• Medial geniculate body (corpus geniculatum
mediale) – hearing center
Subthalamus
• 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
Hypothalamus
Highest autonomic center
• nuclei x transversal and longitudinal zones
• Crossing of optic nerve (chiasma opticum)
• hypophysis
• Mammillary bodies (corpora mamillaria)
Hypothalamus
Hypothalamus – fyziology
Hormones (blood), nerves, CSF

HYPOTHALAMUS

Endocrine + autonomic system


HOMEOSTASIS
emotions (= LIMBIC SYSTEM)
Telencephalon = Cerebrum
• Pallium (pars pallialis; pallium) 
cerebrum (= hemispheres)
• Basal part (pars basilaris)  nuclei
basales = bazal ganglias
• Septal part (pars septalis)  septum
Pallium
• 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 parcellation
(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; nuclei 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 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