Copyright © 2006 by Allyn and Bacon

Copyright © 2006 by Allyn and Bacon

Chapter 3The Anatomy of the Nervous SystemThe Systems, Structures, and Cells that Make Up Your Nervous SystemThis multimedia product and its contents are

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General Layout of the Nervous System

Central Nervous System (CNS)Brain (in the skull)Spinal Cord (in the spine)

Peripheral Nervous System (PNS)Located outside of the skull and

spineServes to bring information into the

CNS and carry signals out of the CNS


General Layout of the Nervous System

Peripheral Nervous SystemSomatic Nervous System

Afferent nerves (sensory) Efferent nerves (motor)

Autonomic Nervous System Sympathetic and parasympathetic nerves Both are efferent


Autonomic Nervous System

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


Autonomic Nervous System

Sympathetic Thoracolumbar “fight or flight” Second stage

neurons are far from the target organ

Parasympathetic Craniosacral “rest and restore” Second stage

neurons are near the target organ



Meninges, Ventricles, and CSF

CNS - encased in bone and covered by three meningesDura mater - tough outer membrane

Arachnoid membrane - weblikePia mater - adheres to CNS surface

Cerebrospinal fluid (CSF)Fluid serves as cushion


Protecting the Brain

Chemical protectionThe blood-brain barrier – tightly-packed

cells of blood vessel walls prevent entry of many molecules

Physical protectionSkull MeningesCerebrospinal fluid (CSF)


Cells of the Nervous System

Neurons – structural classesMultipolarUnipolarBipolarInterneurons

Glial cells – various types, provide a wide variety of supportive functions



Glial Cells

Myelin producersOligodendrocytes (CNS)Schwann cells (PNS)

Astrocytes – largest glia, many functions

Microglia – involved in response to injury or disease



Terminology Note

CNS PNSMyelin-providing glia

Oligodendrocytes Schwann Cells

Clusters of cell bodies

Nuclei (singular nucleus)

Ganglia(singular ganglion)

Bundles of axons

Tracts Nerves


Neuroanatomical Techniques

Golgi stain – allows for visualization of individual neurons

Nissl stain – selectively stains cell bodies

Electron microscopy – provides information about the details of neuronal structure


Neuroanatomical Tracing Techniques

Anterograde (forward)tracing where axons project

to Retrograde (backward)

tracing where axons are projecting from




Neuroanatomical Directions

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


Sections of the Brain

Horizontal – a slice parallel to the ground

Frontal (coronal) – slicing bread or salami

Sagittal – a midsagittal section separates the left and right halves



The Spinal Cord

Gray matter – inner component – primarily cell bodies

White matter – outer – mainly myelinated axons

Dorsal – afferent, sensory Ventral – efferent, motor


The Five Major Divisions of the Brain


The Five Major Divisions of the Brain


Major Structures of the Brain

Myelencephalon = medullaComposed largely of tractsOrigin of the reticular formation

MetencephalonMany tractsPons – ventral surfaceCerebellum - coordination



Mesencephalon Tectum (dorsal surface)

Inferior colliculi – audition

Superior colliculi - vision

Tegmentum (ventral) – 3 ‘colorful’ structuresPeriaqueductal gray – analgesia

Substantia nigra – sensorimotor

Red nucleus– sensorimotor



DiencephalonThalamus – sensory relay nucleiHypothalamus

Regulation of motivated behaviors Controls hormone release by the pituitary

TelencephalonCerebral cortexLimbic systemBasal ganglia


Telencephalon – Cerebral Cortex

Convolutions serve to increase surface area.

Longitudinal fissure – a groove that separates right and left hemispheres

Corpus callosum – largest hemisphere-connecting tract



Telencephalon – Subcortical structures

Limbic system – regulation of motivated behaviorsMammillary bodies, hippocampus,

amygdala, fornix, cingulate, septum Basal ganglia motor system

Amygdala, striatum (caudate nucleus + putamen), globus pallidus



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Copyright © 2006 by Allyn and Bacon