Download Lecture 05

Chapter 3
The Anatomy of the
Nervous System
The Systems, Structures, and
Cells that Make Up Your
Nervous System
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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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General Layout of the Nervous
System
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Peripheral Nervous System
• Somatic Nervous System
 Afferent nerves (sensory)
 Efferent nerves (motor)
• Autonomic Nervous System
 Sympathetic and parasympathetic nerves
 Both are efferent
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Autonomic Nervous System
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All nerves are efferent
Sympathetic and parasympathetic
nerves generally have opposite effects
Two-stage neural paths, neuron exiting
the CNS synapses on a second-stage
neuron before the target organ
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Autonomic Nervous System
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Sympathetic
Thoracolumbar
“fight or flight”
Second stage
neurons are far from
the target organ
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Parasympathetic
Craniosacral
“rest and restore”
Second stage
neurons are near the
target organ
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Copyright © 2006 by Allyn and
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Meninges, Ventricles, and CSF
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CNS - encased in bone and covered by
three meninges
•
Dura mater - tough outer membrane
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Pia mater - adheres to CNS surface
• Arachnoid membrane - weblike

Cerebrospinal fluid (CSF)
•
Fluid serves as cushion
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Protecting the Brain
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Chemical protection
•
The blood-brain barrier – tightly-packed 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 – structural classes
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Glial cells – various types, provide a
wide variety of supportive functions
• Multipolar
• Unipolar
• Bipolar
• Interneurons
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Copyright © 2006 by Allyn and
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Glial Cells
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Myelin producers
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Astrocytes – largest glia, many functions
Microglia – involved in response to injury
or disease

• Oligodendrocytes (CNS)
• Schwann cells (PNS)
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Copyright © 2006 by Allyn and
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Terminology Note
CNS
Myelinproviding glia
Oligodendrocytes
PNS
Schwann Cells
Clusters of
cell bodies
Nuclei
Ganglia
(singular nucleus)
(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 to
Retrograde (backward)
• tracing where axons are
projecting from
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Copyright © 2006 by Allyn and
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Copyright © 2006 by Allyn and
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Neuroanatomical Directions
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In humans, the spinal cord is bent.
Top of the head = dorsal or superior
Back = dorsal
Medial – towards the middle
Lateral – towards 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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Copyright © 2006 by Allyn and
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The Spinal Cord
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Gray matter – inner component –
primarily cell bodies
White matter – outer – mainly myelinated
axons
Dorsal – afferent, sensory
Ventral – efferent, motor
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The Five Major Divisions of the
Brain
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The Five Major Divisions of the
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
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Mesencephalon
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Tectum (dorsal surface)
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Tegmentum (ventral) – 3 ‘colorful’ structures
• Inferior colliculi – audition
• Superior colliculi - vision
• Periaqueductal gray – analgesia
• Substantia nigra – sensorimotor
• Red nucleus– sensorimotor
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Major Structures of the Brain
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Diencephalon
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Thalamus – sensory relay nuclei
Hypothalamus
 Regulation of motivated behaviors
 Controls hormone release by the pituitary
Telencephalon
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Cerebral cortex
Limbic system
Basal ganglia
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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 hemisphereconnecting tract
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Copyright © 2006 by Allyn and
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Telencephalon – Subcortical structures
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Limbic system – regulation of motivated
behaviors
• Mammillary bodies, hippocampus, amygdala,
fornix, cingulate, septum
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Basal ganglia motor system
• Amygdala, striatum (caudate nucleus +
putamen), globus pallidus
Copyright © 2006 by Allyn and
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Copyright © 2006 by Allyn and
Bacon
Copyright © 2006 by Allyn and
Bacon