0. Neuroanatomie Aantekeningen
HC1 + 2 Neuroanatomie I + II
Hersenen amorfe structuur + veel namen gegeven voordat functie bekend was -> lastig
In kleine hersenen (cerebellum) zitten 10x zo veel neuronen als in het cerebrum
- Tegenstelling met naam!
Brein werkt met elektrische stroompjes/pulsjes -> dat zijn actiepotentialen
- Actiepotentialen gegenereerd door neuronen
Neuron bestaat uit
- Het cellichaam -> het soma
- Axon
- Dendriet
Action potentials travel along axons and their presence is signaled to the next neuron at the synapse.
Neurotransmitters convey the message at the synapse.
Neurons -> voorkennis, moet paraat zijn
- Excitable elements
- Dendrite – soma – axon
- Action potential – no attenuation – axon hillock
o Axon hillock -> last site of soma where membrane potentials are summated before
being transmitted to the axon
- Myelin sheet – Ranvier node – saltatory conduction
- Synapse – neurotransmitter – post synaptic potential
- EPSP – IPSP – attenuation – summation
o Attenuation -> reduction of amplitude of an electric current
o Summation -> process that determines whether or not an action potential will be
generated by the combined effect of excitatory and inhibitory signals
▪ Temporal summation -> repeated inputs
▪ Spatial summation -> through multiple simultaneous inputs
Gliacellen ->
- CNS ->
o Astrocyte (!) -> protects brain
▪ Support for CNS
▪ Help form blood-brain barrier
▪ Secrete neurotrophic factors
▪ Take up K+ and neurotransmitters
o Microglial cell (modified immune cells) -> act as scavengers
o Ependymal cell -> create barriers between compartments
o Oligodendrocyte -> form myelin sheaths
- PNS
o Satellite cells -> support of cell bodies
o Schwann cells ->
▪ secrete neurotrophic factors
▪ form myelin sheaths
,CNS astrocytes
Buitenkant brein is helemaal afgegrensd door uitlopers van asterocyten!
Astrocytic extensions cover the entire outside surface of the brain
- glia limitans perivascularis
o surrounds all bloodvessels
o (is part of) the blood-brain barrier
▪ Capillaries covered by astrocytes
- Glia limitans superficialis
o Borders on subarachnoid space
o (part of) brain-liquor barrier
Astrocytic extensions cover all uncovered surfaces of the neuronal
somata, dendrites and (unmyelinated) axons
- Structural support
- Control of ECF by uptake of K+ and
neurotransmitters
o K+ important for electrical balance
neuron, too much K+ will be taken up and
transported away by astrocytes
- Cell membrane of neuron is always covered by
something (astrocytes) -> except for synapses ->
covered by synapse
CNS oligodendrocytes
- Form myelin sheaths in CNS -> improve conduction
speed
- Astrocytes cover unmyelinated axons
CNS Ependymal cells -> epithelia of ventricles
Squamous to columnar epithelial lining of the ventricles
- May be ciliated, cilia beat to circulate CSF (liquor)
- Form a permeable barrier between CSF and ECF ->
because of this there is a layer of astrocytes under
the ependymal cells
- Forms the choroid plexus
o Production of cerebrospinal fluid CSF
▪ Capillair -> ultrafiltraat van plasma
▪ Dit bewerkt door ependymcellen
▪ Wordt CSF (glucose, oxygen,
vitamins, ions Na1, Cl2, Mg21 etc
o Absorption of waste and unnecessary
solutes from the CSF
,CNS microglial cells
- Mononuclear phagocyte
- Enige soort cel dat niet uit het neuro-ectoderm komt
(ependymcellen, oligodendrocyten, asterocyten, neuronen wel)
- Bestaan in inactieve vorm -> als ze niet actief worden kan
ziektebeeld geven
o Andersom overactief kunnen ook ziekten geven
PNS Satellite cells
- Similar in function to
the astrocytes
PNS Schwann cells
Cover all axons in PNS
- Myelinating SC -> form myelin sheaths for myelinated axon
- Non-myelinating SC -> envelop non-myelinated axons
o Remak bundles
o Er zitten gleufjes in ->
daarin lopen de axonen
(6-10 axonen) -> Remak
Kortom -> cells of the nervous system
- Neurons – excitable elements
- Astrocytes – blood brain barrier
and CNS neuronal protection
- Oligodendrocytes – CNS myelin
- Microglial cells – waste disposal
- Ependymal cells – ventricular epithelium and CSF production
- Satellite cells – PNS neuronal protection
- Schwann cells – PNS myelin
Subdivisions and components
- The brain is a jelly-like tissue consisting of myriads of
interconnected neurons
- Sensors feed information into the brain through
afferent/sensory axons/nerves/tracts ->
- ‘’The brain brains’’ ->
- Efferent/motor axons/nerves/tracts feed information to effectors (muscles/glands)
o Twee manieren van reageren op prikkels -> spieren en klieren
Onderverdeling -> zie plaatje
, Coarse subdivisions of the nervous system
- CNS -> brain, spinal cord
- PNS -> cranial nerves, spinal nerves, ganglia
Functional subdivisions -> fluid way of dividing
- Somatic -> (somato)motor, sensory
- Autonomic -> sympathetic, parasympathetic, enteric
Please note
- A nerve (zenuw) consists of a bundle of (afferent and/or efferent) axons surrounded by a
connective tissue sheath, and is located in the PNS
- Tracts and fascicles (bundle of nerve fibers) etc. consist of bundles of either afferent or efferent
axons, and are present in the CNS
- A neuron usually consists of
o An (afferent) dendritic tree
o A cell body (soma)
o An (efferent) axon that branches into axon terminals
- The word ‘’neuron’’ however often refers to just the cell body
- Do not confuse the words nerve, tract/fascicle, neuron, and axon!
o Axon is een uitloper van één neuron
o Zenuw bundel met heel veel verschillende axonen in perifere zenuwstelsel
Major components of the CNS
- Brain
o Cerebrum (grote hersenen) -> heeft twee hemispheren
o Diencephalon (tussenhersenen, koppelstuk losse
hemispheren op as/axis (hersenstam en ruggenmerg)
o Cerebellum (kleine hersenen)
o Brainstem (voortzetting van ruggenmerg)
▪ Mesencephalon (middenhersenen)
▪ Pons
▪ Medulla oblongata (verlengde merg, lijkt op
ruggenmerg qua structuur)
- Spinal cord
Cerebrum subdivisions
Hemipheres and corpus callosum
Lobes -> vernoemd naar de botten (os) waar ze onder zitten
- Frontal
- Parietal
- Occipital
- Temporal
Surface indentation
- Central sulcus
- Lateral fissure (red arrow) (sulcus lateralis)
Hersenschors -> convoluted surface -> je ziet aan de buitenkant maar 30%, de rest zit samengedrukt in
de diepte
Je hoeft niet alle sulci en gyri te kennen (ze hebben niet allemaal een functie) -> alleen de belangrijkste
HC1 + 2 Neuroanatomie I + II
Hersenen amorfe structuur + veel namen gegeven voordat functie bekend was -> lastig
In kleine hersenen (cerebellum) zitten 10x zo veel neuronen als in het cerebrum
- Tegenstelling met naam!
Brein werkt met elektrische stroompjes/pulsjes -> dat zijn actiepotentialen
- Actiepotentialen gegenereerd door neuronen
Neuron bestaat uit
- Het cellichaam -> het soma
- Axon
- Dendriet
Action potentials travel along axons and their presence is signaled to the next neuron at the synapse.
Neurotransmitters convey the message at the synapse.
Neurons -> voorkennis, moet paraat zijn
- Excitable elements
- Dendrite – soma – axon
- Action potential – no attenuation – axon hillock
o Axon hillock -> last site of soma where membrane potentials are summated before
being transmitted to the axon
- Myelin sheet – Ranvier node – saltatory conduction
- Synapse – neurotransmitter – post synaptic potential
- EPSP – IPSP – attenuation – summation
o Attenuation -> reduction of amplitude of an electric current
o Summation -> process that determines whether or not an action potential will be
generated by the combined effect of excitatory and inhibitory signals
▪ Temporal summation -> repeated inputs
▪ Spatial summation -> through multiple simultaneous inputs
Gliacellen ->
- CNS ->
o Astrocyte (!) -> protects brain
▪ Support for CNS
▪ Help form blood-brain barrier
▪ Secrete neurotrophic factors
▪ Take up K+ and neurotransmitters
o Microglial cell (modified immune cells) -> act as scavengers
o Ependymal cell -> create barriers between compartments
o Oligodendrocyte -> form myelin sheaths
- PNS
o Satellite cells -> support of cell bodies
o Schwann cells ->
▪ secrete neurotrophic factors
▪ form myelin sheaths
,CNS astrocytes
Buitenkant brein is helemaal afgegrensd door uitlopers van asterocyten!
Astrocytic extensions cover the entire outside surface of the brain
- glia limitans perivascularis
o surrounds all bloodvessels
o (is part of) the blood-brain barrier
▪ Capillaries covered by astrocytes
- Glia limitans superficialis
o Borders on subarachnoid space
o (part of) brain-liquor barrier
Astrocytic extensions cover all uncovered surfaces of the neuronal
somata, dendrites and (unmyelinated) axons
- Structural support
- Control of ECF by uptake of K+ and
neurotransmitters
o K+ important for electrical balance
neuron, too much K+ will be taken up and
transported away by astrocytes
- Cell membrane of neuron is always covered by
something (astrocytes) -> except for synapses ->
covered by synapse
CNS oligodendrocytes
- Form myelin sheaths in CNS -> improve conduction
speed
- Astrocytes cover unmyelinated axons
CNS Ependymal cells -> epithelia of ventricles
Squamous to columnar epithelial lining of the ventricles
- May be ciliated, cilia beat to circulate CSF (liquor)
- Form a permeable barrier between CSF and ECF ->
because of this there is a layer of astrocytes under
the ependymal cells
- Forms the choroid plexus
o Production of cerebrospinal fluid CSF
▪ Capillair -> ultrafiltraat van plasma
▪ Dit bewerkt door ependymcellen
▪ Wordt CSF (glucose, oxygen,
vitamins, ions Na1, Cl2, Mg21 etc
o Absorption of waste and unnecessary
solutes from the CSF
,CNS microglial cells
- Mononuclear phagocyte
- Enige soort cel dat niet uit het neuro-ectoderm komt
(ependymcellen, oligodendrocyten, asterocyten, neuronen wel)
- Bestaan in inactieve vorm -> als ze niet actief worden kan
ziektebeeld geven
o Andersom overactief kunnen ook ziekten geven
PNS Satellite cells
- Similar in function to
the astrocytes
PNS Schwann cells
Cover all axons in PNS
- Myelinating SC -> form myelin sheaths for myelinated axon
- Non-myelinating SC -> envelop non-myelinated axons
o Remak bundles
o Er zitten gleufjes in ->
daarin lopen de axonen
(6-10 axonen) -> Remak
Kortom -> cells of the nervous system
- Neurons – excitable elements
- Astrocytes – blood brain barrier
and CNS neuronal protection
- Oligodendrocytes – CNS myelin
- Microglial cells – waste disposal
- Ependymal cells – ventricular epithelium and CSF production
- Satellite cells – PNS neuronal protection
- Schwann cells – PNS myelin
Subdivisions and components
- The brain is a jelly-like tissue consisting of myriads of
interconnected neurons
- Sensors feed information into the brain through
afferent/sensory axons/nerves/tracts ->
- ‘’The brain brains’’ ->
- Efferent/motor axons/nerves/tracts feed information to effectors (muscles/glands)
o Twee manieren van reageren op prikkels -> spieren en klieren
Onderverdeling -> zie plaatje
, Coarse subdivisions of the nervous system
- CNS -> brain, spinal cord
- PNS -> cranial nerves, spinal nerves, ganglia
Functional subdivisions -> fluid way of dividing
- Somatic -> (somato)motor, sensory
- Autonomic -> sympathetic, parasympathetic, enteric
Please note
- A nerve (zenuw) consists of a bundle of (afferent and/or efferent) axons surrounded by a
connective tissue sheath, and is located in the PNS
- Tracts and fascicles (bundle of nerve fibers) etc. consist of bundles of either afferent or efferent
axons, and are present in the CNS
- A neuron usually consists of
o An (afferent) dendritic tree
o A cell body (soma)
o An (efferent) axon that branches into axon terminals
- The word ‘’neuron’’ however often refers to just the cell body
- Do not confuse the words nerve, tract/fascicle, neuron, and axon!
o Axon is een uitloper van één neuron
o Zenuw bundel met heel veel verschillende axonen in perifere zenuwstelsel
Major components of the CNS
- Brain
o Cerebrum (grote hersenen) -> heeft twee hemispheren
o Diencephalon (tussenhersenen, koppelstuk losse
hemispheren op as/axis (hersenstam en ruggenmerg)
o Cerebellum (kleine hersenen)
o Brainstem (voortzetting van ruggenmerg)
▪ Mesencephalon (middenhersenen)
▪ Pons
▪ Medulla oblongata (verlengde merg, lijkt op
ruggenmerg qua structuur)
- Spinal cord
Cerebrum subdivisions
Hemipheres and corpus callosum
Lobes -> vernoemd naar de botten (os) waar ze onder zitten
- Frontal
- Parietal
- Occipital
- Temporal
Surface indentation
- Central sulcus
- Lateral fissure (red arrow) (sulcus lateralis)
Hersenschors -> convoluted surface -> je ziet aan de buitenkant maar 30%, de rest zit samengedrukt in
de diepte
Je hoeft niet alle sulci en gyri te kennen (ze hebben niet allemaal een functie) -> alleen de belangrijkste
