Download Conference Outline 1

Psyc 311A, fall 2008
Conference week 1
Sept 9th to 11th
TA: Jürgen Germann; e-mail: [email protected]
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Overview:
1. The basic anatomy of the Central Nervous System
(CNS)
2. Cells of the CNS
3. Views and Planes of the CNS
4. Directional terms
5. Subdivisions of the cerebral hemispheres: the
lobes
1. The basic anatomy of the Central
Nervous System (CNS)
Cerebrum
Brainstem
Spinal cord
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Further subdivisions are best seen in a medial view
Cerebral hemisphere
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Brainstem
Midbrain
Pons and
Cerebellum
Medulla
oblongata
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I. CEREBRUM
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Cerebral Hemispheres
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Cerebral cortex (Grey matter surrounding the hemispheres)
White matter (Myelinated nerve axons connecting different areas in the brain)
Subcortical grey matter or Subcortical nuclei (Grey matter within the cerebral
hemispheres. e.g. Basal Ganglia)
Ventricular system (Cavities in the brain filled with Cerebrospinal fluid: Lateral
Ventricles, Foramen of Monro/Interventricular Foramen)
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Diencephalon
The Diencephalon is the part of the Brain that lies within the two cerebral
hemispheres and forms the roof of the Brainstem.
It has important connections for example to sensory, motor pathways and
acts as a relay station for most senses.
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Thalamus; the largest structure of the Diencephalon
Hypothalamus
Subthalamus
Epithalamus
Ventricular system: Third ventricle
Grey matter white matter
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Gray matter (nerve
cell bodies)
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White matter
(axons, fibre
bundles)
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Cortex
Subcortical grey
matter (Basal
Ganglia)
Efferent = away
from a structure
Afferent = towards
a structure
NOTE: the
Diencephalon is
situated medially to
the Sylvian fissure
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II. BRAINSTEM
The Brainstem is siutated in between the Diencephalon and the spinal cord of the
CNS. It controls bodily functions and special senses. All the white matter fiber tracks
connecting the cerebrum with the spinal cord travel within the brainstem. The
brainstem also contains a number of nuclei for visceral, special senses and other
functions.
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Ventricular system: fourth ventricle & aqueduct of
Sylvius/Cerebral Aqueduct
Parts:
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Midbrain (Mesencephalon)
Pons and Cerebellum (Metencephalon)
Medula Oblongata (Myelencephalon)
THE CEREBELLUM
The Cerebellum that is part of the Metencephalon is important for motor coordination
and smoothness of motor responses, regulation of muscle tone and maintenance of
equilibrium. It is composed of two cerebellar hemispheres that have ipsilateral
connections with the body.
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Major subdi visions of the central nervous system
Major components
Brain
(Encephalon)
Cerebrum
Brainstem
S pinal cord
Embryonic componenet
Adult derivate
Ventricular
cavity
Telencephalon
(Endbrain)
Cerebral
hemispheres
(cortex, white
matter and
subcortical grey)
Lateral
ventricles
Diencephalon
(Interbrain)
Diencephalon
(thalamus, hypo-,
sub-, and
epithalamus)
Third
ventricle
Mesencephalon
(M idbrain)
Mesencephalon
(M idbrain)
Midbrain
Cerebral
aqueduct
(aqueduct of
S ylvius)
Rhombencephalon
(Hindbrain)
Metencephalon
(Afterbrain)
Pons and
Cerebellum
Fourth
ventricle
Myelencephalon
(M edulla)
Medulla
oblongata
Prosencephalon
(Forebrain)
Neural tube
S pinal cord
Central canal
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Cerebrum
Brainstem
2. Cells of the CNS: nerve cells
Nerve cells consist of a cell body (or
(neuron)
soma) with branching dendrites and a
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long axon.
Information flow is from the dendrites to
the soma (axon hillock) and down the
axon in form of action potentials.
There are many different types of nerve
cells that have different functions in the
CNS.
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For example pyramidal cells with their long
axons form the corticospinal tract, whereas,
stellate and granule cells have short axons
and form local processing units in the grey
matter cortex.
Neuronal information is transferred
between nerve cells through synapses.
Neurotransmitter is released at the axon
terminals transferring the signal to the
postsynaptic dendrite of another cell.
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Nerve cells
„Beside
nerve cells the brain consists of
glial cells, they make up 90% of brain
cells. They do not convey neuronal
signals but perform many of the protective
and supportive functions of the nerve
cells. There are many types of glial cells:
astrocytes, oligodendrocytes, microglial
cells etc.
3. Views and Planes of the CNS
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3 views:
‰ Lateral view,Medial view, Ventral/orbital view
3 planes
‰ Horizontal/axial plane/section, Coronal/frontal plane, Sagittal
plane
Lateral view
(what
hemisphere?)
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Medial view
ventral/orbital view
Planes/axes
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Coronal/frontal plane
Horizontal/axial plane
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Sagittal plane
4. Directional terms
dorsal
rostral
caudal
Cerebral hemisphere,
Diencephalon
rostral
ventral
dorsal
ventral
Brainstem,
Spinal cord
caudal
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Directional terms
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Rostral = towards the beak/mouth (rostrum = latin ‘beak’)
Caudal = towards the tail (caudum= latin ‘tail’)
Ventral = towards the belly (ventrum= latin ‘womb’)
Dorsal = towards the back (dorsum = latin ‘back’) ;
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Can also use superior/inferior; anterior/posterior; those do not change
between brainstem and cerebrum
The neuronal axis changes between the cerebrum and the
brainstem/spinal cord. This is because humans walk upright and thus
the cerebrum in tilted by 900 compared to other species.
Other useful terms:
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- Unilateral (only on one hemisphere)
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- Bilateral (on both hemispheres)
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- Ipsilateral (in the same hemisphere)
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- Contralateral (in the opposite hemisphere)
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- Distal (far from a structure)
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- Proximal (close to a structure)
Directional terms
lateral
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medial medial
lateral
Medial =
closer to the midline
Lateral =
further away
from the midline
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5. Subdivisions of the cerebral hemispheres: the lobes
Central sulcus
Parietoccipital
sulcus
Sylvian
fissure
Preoccipital
notch
5. Subdivisions of the cerebral
hemispheres: the lobes
The cerebral hemispheres can be divided into four lobes (frontal, parietal, occipital and
temporal). Some scientists though have added a fifth lobe that is the grouping of several
medial structures that are involved in memory and emotions. This lobe is called the
Limbic lobe. Carpenter in addition refers to the Insula as the Insular lobe. Very few
anatomists agree with the separation of the insular cortex into a separate lobe.
The determining landmarks to separate the different cerebral lobes are:
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the Lateral/Sylvian fissure,
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the Central/Rolandic fissure,
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the Parietooccipital sulcus,
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and the Preoccipital notch.
The central sulcus forms the boundary between the frontal and
parietal lobes. An imaginary line traced between the parietooccipital sulcus and the preoccipital
notch delineates the occipital lobe, and an imaginary extension of the Sylvian fissure towards
the previously defined imaginary line separates the frontal and parietal lobes from the temporal
lobe
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