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Chapter 3
The Anatomy of the
Nervous System
The Systems, Structures, and
Cells That Make Up Your
Nervous System
General Layout of the
Nervous System
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Central Nervous System (CNS)
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Brain (in the skull)
Spinal Cord (in the spine)
Peripheral Nervous System (PNS)
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Located outside of the skull and spine
Serves to bring information into the CNS and
carry signals out of the CNS
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Major divisions of the nervous system
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Meninges, Ventricles, and
Cerebrospinal Fluid (CSF)
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CNS encased in bone and
covered by three meninges
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Dura mater – tough outer membrane
Arachnoid membrane – web-like
Pia mater – adheres to CNS surface
Cerebrospinal fluid (CSF)
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Fluid serves as cushion
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Meninges
http://faculty.une.edu/com/fwillard/Meninges/pages/mening02.htm

http://faculty.une.edu/com/fwillard/Menin
ges/pages/mening02.htm
Protecting the Brain
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Chemical protection
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The blood-brain barrier – tightlypacked cells of blood vessel walls
prevent entry of many molecules
Physical protection
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Skull
Meninges
Cerebrospinal fluid (CSF)
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Cells of the Nervous System
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Neurons
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Specialized cells for the reception,
conduction, and transmission of
electrochemical signals
Many sizes and shapes
Glial cells
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Outnumber neurons 10:1
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Cells of the
Nervous
System
Major external
features of
a typical neuron
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Cells of the Nervous System (continued)
The
cell
membrane
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Cells of the Nervous System (continued)
Four
types
of
neurons
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Glial Cells:
The Forgotten Majority
Four classes:
 Oligodendrocytes – extensions rich in myelin
create myelin sheaths in CNS
 Schwann cells – similar to function of
oligodendrocytes but in PNS, can guide
axonal regeneration
 Astrocytes – largest glia, star-shaped, many
functions
 Microglia – involved in response to injury or
disease
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Terminology Note
CNS
PNS
Myelin-providing
glia
Oligodendrocytes
Schwann cells
Clusters of cell
bodies
Nuclei
(singular nucleus)
Ganglia
(singular ganglion)
Bundles of axons
Tracts
Nerves
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Neuroanatomical Techniques
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Golgi stain – allows for
visualization of individual
neurons
Nissl stain – selectively stains
cell bodies
Electron microscopy – provides
information about the details of
neuronal structure
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Neuroanatomical Tracing
Techniques
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Anterograde (forward)
 tracing where axons project
away from an area
Retrograde (backward)
 tracing where axons are
projecting into an area
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Directions in the Vertebrate
Nervous System
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Directions in the Vertebrate
Nervous System (continued)
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Directions in the Vertebrate
Nervous System (continued)
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Anatomical directions ignore the fact
that humans walk upright. Therefore,
top of the head both “dorsal” (back)
and “superior” (top)
Other directions:
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Medial – toward the middle
Lateral – toward the side
Proximal – close
Distal – far
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Sections of the Brain
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Horizontal – a slice parallel to the
ground
Frontal (coronal) – slicing bread or
salami
Sagittal – a midsagittal section
separates the left and right halves
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section
The Spinal Cord
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Gray matter – inner component,
primarily cell bodies
White matter – outer area, mainly
myelinated axons
Dorsal – afferent, sensory
Ventral – efferent, motor
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The Spinal Cord (continued)
Dorsal and ventral roots
Spinal cross section
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The Five Major Divisions of the
Brain
Early
development of the
mammalian
brain
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The Five Major Divisions of the
Brain (continued)
The divisions
of the adult
human brain
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Major Structures of the Brain
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Myelencephalon = medulla
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Composed largely of tracts
Origin of the reticular formation
Metencephalon
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Many tracts
Pons – ventral surface
Cerebellum – coordination
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Major Structures
of the Brain
Structures of the
human
myelencephalon
(medulla) and
metencephalon
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Major Structures of the
Brain (continued)
The human
mesencephalon
(midbrain)
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Major
Structures
of the
Brain
(continued)
The human
diencephalon
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Telencephalon – Cerebral
Cortex
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Convolutions serve to increase
surface area
Longitudinal fissure – a groove
that separates right and left
hemispheres
Corpus callosum – largest
hemisphere-connecting tract
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Major fissures of the cerebral hemispheres
Lobes of the cerebral hemispheres
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Telencephalon – Subcortical
Structures
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Limbic system – regulation of motivated
behaviors
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Mammillary bodies, hippocampus,
amygdala, fornix, cingulate, septum
Basal ganglia motor system
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Amygdala, striatum (caudate nucleus +
putamen), globus pallidus
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Telencephalon –
Subcortical
Structures
The major
structures of
the limbic
system
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Telencephalon –
Subcortical
Structures
The basal ganglia
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Summary of major brain structures
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