Download Introduction to the Structure and Function of the Nervous System

Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
CHAPTER
3 & Bartlett Learning, LLC
© Jones
NOT FOR SALE OR DISTRIBUTION
Introduction to the
Structure and Function
of the Nervous System
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
Jones & Bartlett Learning, LLC
© Jones & Bartlett Learning, LLC
OT FOR SALE OR
DISTRIBUTION
SALE
ORmore
DISTRIBUTION
body
to move
effectively as a whole
Structure and Function of the NOT FOR
Nervous System
and to achieve purposeful movement. This
coordination of voluntary muscles makes
The nervous system is a complex regulatory syspossible complex activities, such as walktem that, along with the endocrine system, controls
piano,
and using
a
© Jones
Bartlett
Learning, LLC ing, running, playing a ©
Jones
& Bartlett
Learning
and coordinates
activities&
and
functions throughout
computer, as well as simple activities, such
the body, internally
and externally,
sending,
reNOT FOR SALE OR DISTRIB
NOT FOR
SALE by
OR
DISTRIBUTION
as maintaining muscle tone and posture
ceiving, and sorting electrical impulses and chemiwhile at rest.
cal signals. Disruption of any part of the nervous
• Monitoring and recognizing stimuli (and
system affects body function in some way, either
information) within the environment, and
internally or externally.
then directing
an appropriate
to
© JonesThe
& nervous
Bartlett
Learning,
LLC
© Jones
& Bartlettresponse
Learning,
LLC
system
consists of the
central nerthe stimuli.
This
function
makes
possible
NOT vous
FORsystem,
SALE
OR
DISTRIBUTION
NOT
FOR
SALE
OR
DISTRIBUTION
which includes the brain and spinal
reflex actions, such as pulling away one’s
cord, and the peripheral nervous system, which
hand from a hot surface, as well as perceivincludes nerve fibers extending from the brain and
ing music being played in the next room.
spinal cord that carry information between the cen• Monitoring and coordinating internal body
tral nervous system and the rest of the body. The
Jones & Bartlettperipheral
Learning,
LLC
© Jones states
& Bartlett
Learning,
so that internal
organs LLC
function as a
nervous system is further divided into two
unit,
internal
body
constancy
(homeostasis)
OT FOR SALE OR
DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
parts:
the afferent (sensory) system, which carries
is maintained, and protective action is taken.
messages from other parts of the body to the central
For example, in response to a lack of oxynervous system, and the efferent (motor) system,
gen, more rapid breathing occurs; the body
which carries messages from the central nervous
shivers in response to cold; and when threat
system to other
parts of the
(see Table
3-1).
© Jones
& body
Bartlett
Learning,
LLC or danger is encountered,
© Jones
Bartlett Learning
the heart&
beats
NOT FOR SALE OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
more rapidly.
Function of the Nervous System
Other functions, such as display of personality
Functions of the nervous system include the
traits, language, speech, learning, remembering,
following:
feeling emotion, reasoning, and generating and
© Jones• &
Bartlettand
Learning,
LLCresponses
© Jones
Bartlett
Learning,
LLC
Organizing
directing motor
relaying thoughts,
are also&controlled
by the
­nervous
of
the
voluntary
muscle
system,
enabling
the
system—specifically,
by
the
brain.
NOT FOR SALE OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
33
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 33
28/10/16 12:18 PM
© Jones & Bartlett Learning, LLC
Jones & Bartlett Learning, LLC
34 Chapter
3 • Introduction
to
the
Structure
and Function
of the Nervous
System
NOT
FOR SALE
OR DISTRIBUTION
OT FOR SALE OR DISTRIBUTION
dendrites conduct nerve impulses toward the cell
body after receiving information from other neurons. Fibers that carry information
from parts
of
© Jones & Bartlett Learning, LLC
© Jones
& Bartlett
Learning
I. Central nervous system
the body to the brain are called afferent neurons
NOT FOR SALE OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
(sensory neurons). Fibers that carry information
A.Brain
from the brain to other parts of the body are called
B. Spinal cord
efferent neurons (motor neurons).
II. Peripheral nervous system
Surrounding neurons is a fatty sheath called
A. Afferent (sensory)
myelin,
which,
much like&
theBartlett
covering ofLearning,
electrical
© Jones
& Bartlett Learning, LLC
© Jones
LLC
B. Efferent (motor)
cords,
provides
insulation,
ensuring
that
electrical
NOT FOR1.SALE
OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
Somatic nervous system
impulses are able to flow smoothly and reliably.
2. Autonomic nervous system
Information is passed from neuron to neuron by
a. Sympathetic nervous system
both electrical and chemical impulses. The electrical impulse, which has been picked up by the
b. Parasympathetic nervous system
Jones & Bartlett Learning, LLC
© Jones
& Bartlett
Learning,
LLC
dendrites,
is passed through
the cell
body to the
electrical
then moves down
OT FOR SALE OR DISTRIBUTION
NOTaxon.
FORThe
SALE
ORimpulse
DISTRIBUTION
Nerve Cells
the full length of the axon until it reaches its tip.
Specialized cells called neurons are the functional
At the tip of the axon are tiny processes, which
units of the nervous system. Neurons transmit
release chemicals known as neurotransmitters.
messages to and from the brain. They consist of a
Neurotransmitters, chemically transfer the impulse
© processes
Jones &
Bartlett
Learning,
LLC
© Jones
& Bartlett Learning
cell body and
(nerve
fibers) that
extend
from one neuron to another across
a space between
NOT
FOR
SALE OR DISTRIB
NOT
FOR
SALE
OR
DISTRIBUTION
beyond the cell body. In most cases, a single long
the two neurons called the synapse. The electrical
nerve fiber called an axon conducts nerve impulses
impulse, through the vehicle of neurotransmitters,
(and information) away from the cell body to
then moves to the next neuron’s dendrites and
other neurons. Smaller, shorter nerve fibers called
the process begins again (see Figure 3-1). After
Table 3-1 The Nervous System (Central and
Peripheral)
© Jones & Bartlett Learning, LLC
Neurons
NOT Figure
FOR 3-1 SALE
OR DISTRIBUTION
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jane Tinkler Lamm.
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 34
28/10/16 12:18 PM
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
Structure
andSALE
Function
of the
Nervous System 35
NOT
FOR
OR
DISTRIBUTION
neurotransmitters are released, they are either taken
• The pia mater is the inner membrane, which
up again by the neuron or destroyed.
lies closest to the brain and spinal cord.
Longer©axons
are
generally
grouped
in
Jones & Bartlett Learning, LLCBetween each of the membrane
© Jones
& Bartlett
Learning
layers
are
bundles. When they are transmitting impulses
spaces.
The
space
between
the
dura
mater
and
the
NOT FOR SALE OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
within the central nervous system, these bundles
inner surface of the bony covering is the epidural
are referred to as tracts. Those bundles located
space; the space between the dura mater and the
outside the central nervous system are referred
arachnoid membrane is the subdural space; and
to as nerves.
the space between the arachnoid membrane and
© Jones & Bartlett Learning, LLC
& Bartlett
Learning, LLC
the pia mater©isJones
the subarachnoid
space.
NOT The
FOR
SALENervous
OR DISTRIBUTION
NOT
FORsystem
SALE
ORprotected
DISTRIBUTION
The central
nervous
is also
Central
System
and cushioned by cerebrospinal fluid (CSF),
The central nervous system is made up of the brain
which is formed by specialized capillaries called
and spinal cord. Bony coverings protect both the
the choroid plexus in inner chambers within the
brain and the spinal cord. On the interior of these
brain called
ventricles.
The cerebrospinal
Jones & Bartlettbony
Learning,
LLC
© Jones
& Bartlett
Learning,
LLC fluid
coverings are
three membranes (meninges)
bathes the brain and spinal cord, circulating from
that DISTRIBUTION
provide additional protection:
OT FOR SALE OR
NOTthe
FOR
SALE OR DISTRIBUTION
ventricles into the subarachnoid space (see
• The dura mater is the outer membrane, lyFigure 3-2). From the subarachnoid space, the
ing closest to the bony covering of the brain
CSF flows to the back of the brain, down around
and spinal cord.
the spinal cord, and then back to the brain, where
• The arachnoid
membrane
is
the
middle
it is reabsorbed into the blood ©
through
the &
arach© Jones & Bartlett Learning, LLC
Jones
Bartlett Learning
membrane,
a
cobweb-appearing
membrane.
noid membrane. The amounts ofNOT
cerebrospinal
fluid
FOR SALE
OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
Figure 3-2 Circulation of Cerebrospinal Fluid
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
Arachnoid
villus
NOT FOR SALE
OR DISTRIBUTION
Cranium
Dura mater
Lateral ventricle
Jones & Bartlett Learning,Third
LLC
ventricle
OT FOR SALE OR DISTRIBUTION
Sinus
Pia mater
Arachnoid
Cerebral cortex
© Jones & Bartlett Learning, LLC
Cerebrum
NOT FOR SALE OR
DISTRIBUTION
Foramen of Monro
Aqueduct
of Sylvius
ventricle
©Fourth
Jones
& Bartlett Learning, LLC
Cerebellum
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
Spinal cord
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jane Tinkler Lamm.
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 35
28/10/16 12:18 PM
© Jones & Bartlett Learning, LLC
Jones & Bartlett Learning, LLC
36 Chapter
3 • Introduction
to
the
Structure
and Function
of the Nervous
System
NOT
FOR SALE
OR DISTRIBUTION
OT FOR SALE OR DISTRIBUTION
produced and absorbed are equally balanced so
and the display of general personality traits, which
that under normal conditions, the amount of CSF
are characteristic of how each individual responds
within the central
nervous
system
remains
constant.
to stimuli.
© Jones & Bartlett Learning, LLC
© Jones & Bartlett Learning
Another protective device is the blood–brain
The brain is protected by the bony covering of
NOT FOR SALE OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
barrier, a structural arrangement of capillaries
the skull (cranium or cranial bones). The largest
that selectively determines which substances can
part of the brain, the cerebrum, is covered with a
move from the blood into the brain. While subthin outer layer of gray matter called the cortex,
stances such as oxygen and glucose are necessary
which contains billions of nerve cells. The cortex
for
brain
survival
and
consequently
move
freely
has three specialized
areas,
serveLearning,
three ma© Jones & Bartlett Learning, LLC
© Jones
& which
Bartlett
LLC
across
the
blood–brain
barrier,
other
potentialharmjor
areas
of
function:
NOT FOR SALE OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
ful substances, such as toxins, are prevented from
• The motor cortex coordinates voluntary
crossing into the brain.
movements of the body.
The central nervous system is composed of
• The sensory cortex is responsible for the
white matter and gray matter. White matter makes
or Learning,
perception of LLC
sensory stimJones & BartlettupLearning,
© Jones recognition
& Bartlett
the inner partLLC
of the brain and the outer poruli, such as touch, pain, smell, taste, vision,
tionDISTRIBUTION
of the spinal cord and consists of myelinated
OT FOR SALE OR
NOT FORandSALE
OR DISTRIBUTION
hearing.
covered axons that conduct nerve impulses. It is
• The associational cortex is involved in cogcalled white matter because of its whitish appearnitive functions such as memory, reasoning,
ance due to the myelin covering. Gray matter
abstract thinking, and consciousness.
makes up the thin outer layer of the brain and the
© of
Jones
& Bartlett
LLCThe cerebrum is divided into©two
Jones
Bartlett Learning
inner portion
the spinal
cord. SmallLearning,
segments
halves,&
called
NOT
FOR
SALE
OR DISTRIB
NOT
FOR
SALE
OR
DISTRIBUTION
of gray matter are also embedded deep within certhe right hemisphere and the left hemisphere.
tain parts of the white matter of the brain. Gray
These two hemispheres communicate with each
matter consists of groups of neuron cell bodies.
other. Dividing the hemispheres and connecting
It is called gray matter because of its grayish apspecific areas of the two hemispheres are bundles
pearance.
Gray matter
of the brain receives,
of nerve fibers
called the&corpus
callosum.
Each
© Jones
& Bartlett
Learning,
LLC sorts,
© Jones
Bartlett
Learning,
LLC
and processes nerve messages, while gray matter
hemisphere has centers for receiving information
NOT of
FOR
SALE
OR
DISTRIBUTION
NOT
FOR
SALE
OR
DISTRIBUTION
the spinal cord serves as a center for reflex acand for initiating responses. The left hemisphere
tion (automatic response to stimuli).
mostly receives information from and sends information to the right side of the body, whereas the
right hemisphere mostly receives information from
Structure and Function
and sends
informationLearning,
to the left side
of the body.
Jones & Bartlettof the Brain
Learning, LLC
© Jones
& Bartlett
LLC
Deep within the cerebral hemispheres are
OT FOR SALE OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
groups of gray matter called basal ganglia, which
The brain is directly connected to the spinal cord
and serves as the primary center for the integraare part of the extrapyramidal system. (Extrapytion, coordination, initiation, and interpretation of
ramidal denotes nerve fiber tracts that lie outside
most nerve messages. It regulates and monitors
the pyramidal tract, a relatively compact group of
many unconscious
body&functions,
such
as heart
nerve fibers that originate from©cells
in the&outer
© Jones
Bartlett
Learning,
LLC
Jones
Bartlett Learning
and respiratory
rate
and
coordinates
most
volunlayer
of
the
brain.)
Extrapyramidal
function
is
NOT FOR SALE
OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
tary movements. In addition, it is the site of higher
concerned with postural adjustment and gross volcognitive processes such as learning, generating and
untary and automatic muscular movements. The
relaying thoughts, reasoning, judgment, memory,
basal ganglia help to maintain tone in muscles in
consciousness, and emotion. The brain also has a
the trunk and extremities, enabling individuals to
© Jones
& function,
Bartlettwhich
Learning,
LLC
© Jones
& Bartlett
LLC
sensory
is responsible
for vision,
maintain balance
and posture
and to Learning,
engage in
NOT hearing,
FOR SALE
OR DISTRIBUTION
FOR
SALE
touch, taste,
and smell. Language funcmovementsNOT
such as
walking.
The OR
basalDISTRIBUTION
ganglia
tion, including the ability to communicate and to
also play a role in enabling individuals to react
comprehend, is also controlled by the brain. Fiswiftly, appropriately, and automatically to stimuli
nally, the brain controls basic behavior patterns
that demand an immediate response, such as after
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 36
28/10/16 12:18 PM
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
Structure
Function
of the Brain 37
NOT FOR
SALEand
OR
DISTRIBUTION
tripping, enabling the individual to adjust his or
others can comprehend them. Language function
her movement to avoid a fall.
is located in the left hemisphere of the cerebrum
Each hemisphere
of
the
cerebrum
is
divided
in most individuals, whether©
they
are rightor
© Jones & Bartlett Learning, LLC
Jones
& Bartlett
Learning
into lobes that contain areas related to specific funcleft-handed. An area located over the temporal and
NOT FOR SALE OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
tions (see Figure 3-3). The frontal lobe is located
parietal lobes, called Wernicke’s area, is the main the front of each hemisphere and contains motor
jor area responsible for receptive function (speech
areas that initiate voluntary movement and skilled
understanding), or the ability to integrate visual
movements, such as those involved in handwritand auditory information so as to understand coming.
Other
areas
in
the
frontal
lobe
control
higher
munication ©
received.
An&
area
located in
front of
© Jones & Bartlett Learning, LLC
Jones
Bartlett
Learning,
LLC
intellectual
functions
such
as
foresight,
analytical
the
temporal
lobe
and
in
the
frontal
cortex,
called
NOT FOR SALE OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
thinking, and judgment. The parietal lobe is located
Broca’s area, is responsible for speaking ability
in the middle of each hemisphere and is primarily
and is closely associated with motor areas that
the sensory area, integrating and interpreting sencontrol the muscles needed for articulation. This
sation such as touch, pressure, pain, and temperaarea contributes to expressive function (speech forJones & Bartlettture.
Learning,
LLC
© Jones
& or
Bartlett
LLC
Some memory
functions are also located in
mation),
the abilityLearning,
to integrate and
coordinate
the parietal
lobe, especially those responsible for
that the OR
meaning
can be comprehended.
OT FOR SALE OR
DISTRIBUTION
NOTwords
FORsoSALE
DISTRIBUTION
storage of sensory memory. The temporal lobe is
A structure known as the thalamus lies within
located under the frontal and parietal lobes and is
the center of the brain. The thalamus acts as a relay
primarily responsible for the interpretation of and
station that sorts, interprets, and directs sensory
distinction between auditory stimuli. The occipital
information. Below the thalamus is the hypothalamus,
© Jones
& or
Bartlett
LLC
© Jones
& Bartlett Learning
lobe is located
at the back
posteriorLearning,
portion of
which coordinates neural and endocrine
activities.
NOT
FOR
SALE OR DISTRIB
NOT
FOR
SALE
OR
DISTRIBUTION
each hemisphere. It is the primary area for recepThis structure helps regulate the body’s internal envition and interpretation of visual stimuli.
ronment and behaviors that are important to survival,
Several parts of the cerebrum are involved in
such as eating, drinking, and reproduction. Below the
the language function, which consists of the prohypothalamus is the pituitary, an endocrine gland.
cess of
integrating
The limbic
system comprises
a group
of struc© Jones
& receiving,
Bartlettinterpreting,
Learning,and
LLC
© Jones
& Bartlett
Learning,
LLC
visual and auditory stimuli as well as the ability
tures consisting of both gray and white matter that
NOT to
FOR
SALE
OR
DISTRIBUTION
NOT
FOR
SALE
OR
DISTRIBUTION
express thoughts in a coordinated way so that
surround the thalamus. The limbic system plays a
Figure 3-3 Areas of Brain Function
Parietal lobe
Jones & Bartlett Learning, LLC
(sensation, intellect,
spatial perception)
OT FOR SALE OR DISTRIBUTION
Wernicke’s area
(language)
© Jones & Bartlett Learning, LLC
lobe
NOT FOR SALE ORFrontal
DISTRIBUTION
(initiation, judgment,
motor, reasoning,
abstraction,
self monitoring)
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
Occipital lobe
(vision)
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
Broca’s area
(speech)
Temporal lobe
(hearing)
CerebellumLLC
© Jones & Bartlett Learning,
(coordination,
balance)
NOT FOR SALE OR DISTRIBUTION
Brain stem © Jones
(breathing, heart rate)
& Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jane Tinkler Lamm.
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 37
28/10/16 12:18 PM
© Jones & Bartlett Learning, LLC
Jones & Bartlett Learning, LLC
38 Chapter
3 • Introduction
to
the
Structure
and Function
of the Nervous
System
NOT
FOR SALE
OR DISTRIBUTION
OT FOR SALE OR DISTRIBUTION
role in expression of instincts, drives, and emotions
surround the spinal cord and protect it. This bony
as well as the formation of memories. A band of
covering, as a whole, forms the vertebral column.
gray matter©called
the
hippocampus
is
involved
The vertebral column consists©ofJones
7 cervical
Jones & Bartlett Learning, LLC
& verBartlett Learning
in learning and long-term memory, helping to
tebrae, located in the neck area; 12 thoracic verNOT FOR SALE OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
determine where important and relevant aspects
tebrae, located in the upper and middle back; and
of facts will be stored.
5 lumbar vertebrae, located in the lower back.
Beneath the occipital lobe of the cerebrum is
The sacrum, located below the lumbar vertebrae,
a structure called the cerebellum. The cerebellum
consists of fused (joined) bone. At the tip of the
is
primarily
responsible
for
the
coordination
and
sacrum is the©coccyx,
or tailbone
(see Figure
3-4).
© Jones & Bartlett Learning, LLC
Jones
& Bartlett
Learning,
LLC
integration
of
voluntary
movement
and
for
the
The
spinal
cord
conducts
impulses
to
and
NOT FOR SALE OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
maintenance of equilibrium, posture, and balance
from the brain. The outer white matter of the
of the body. It also regulates and coordinates fine
spinal cord, which consists of bundles or tracts
movements of the extremities, which are initiated
of myelinated fibers of sensory (afferent) and
by the frontal lobe.
motor (efferent) neurons, conveys electrical
Jones & Bartlett Learning,
LLC
© Jones
& Bartlett
Learning,
LLCbetween
The brain stem,
which is located beneath the
impulses
up and down
the spinal cord
cerebellum
at the base of the brain just above the
peripheral
system (those nerves
OT FOR SALE OR
DISTRIBUTION
NOTthe
FOR
SALE nervous
OR DISTRIBUTION
spinal cord, acts as a relay station, transmitting
lying outside the central nervous system) and
nerve impulses between the spinal cord and the
the brain. In most instances, sensory informabrain. It is the primary center of involuntary
tion traveling up the right side of the spinal cord
functions. Control of vital organ functions, such
©ofJones
LLC
© Jones & Bartlett Learning
as regulation
heartbeat&orBartlett
respiration,Learning,
occurs in
Figure 3-4 The Spine
NOT FOR SALE OR DISTRIB
NOT
FOR
SALE
OR
DISTRIBUTION
the brain stem. Areas in the brain stem also regulate the diameter of blood vessels, contributing to
Posterior Atlas
Anterior
the control of blood pressure. Reflex actions, such
Axis
as coughing and swallowing, are controlled in the
Cervical
brain stem
as well. Finally,
the brainLLC
stem contains
© Jones
& Bartlett
Learning,
© Jones & Bartlettvertebrae
(7)Learning, LLC
scattered groups of cells, called the reticular
Cervical VII
NOT formation,
FOR SALE
OR
DISTRIBUTION
NOT
FOR
SALE
OR
DISTRIBUTION
which are involved in the initiation
and maintenance of wakefulness and alertness.
The brain requires both oxygen and nourishment in the form of glucose in order to function and
survive. Oxygen
and glucose are transported to
Thoracic
Jones & Bartlettto Learning,
LLC
© Jones & Bartlett Learning, LLC
vertebrae
the brain by blood carried by four major arteries:
OT FOR SALE OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
(12)
two carotid arteries and two vertebral arteries.
The vertebral arteries join to form the basilar artery. The carotid and basilar arteries then connect
Thoracic XII
at the base of the brain to form the circle of Willis,
from which©
cerebral
arteries
branch out
to carry
Jones
& Bartlett
Learning,
LLC
© Jones & Bartlett Learning
blood to theNOT
rest ofFOR
the brain.
NOT FOR SALE OR DISTRIB
SALE OR DISTRIBUTION
Structure and Function of the
Spinal Cord and Peripheral
Nervous System
Lumbar V
Sacrum
© Jones & Bartlett Learning, LLC
Cord
NOT The
FORSpinal
SALE
OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
The spinal cord is part of the central nervous system and extends from the brain stem to the lower
part of the back. Bony coverings called vertebrae
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
Lumbar
vertebrae
(5)
Coccyx
© Jane Tinkler Lamm.
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 38
28/10/16 12:18 PM
© Jones & Bartlett Learning, LLC
Jones & Bartlett Learning, LLC
Structure
and
Function
of
the
Spinal
CordSALE
and Peripheral
Nervous System 39
NOT
FOR
OR DISTRIBUTION
OT FOR SALE OR DISTRIBUTION
crosses over to the left side of the brain, so the
the central nervous system carry body sensations
left hemisphere of the brain would, for example,
into the sensory nerve roots (posterior roots) at
interpret pain
in
the
right
hand.
Conversely,
mothe back of the spinal cord, where
they are
© Jones & Bartlett Learning, LLC
© Jones
&then
Bartlett Learning
tor impulses originating in the left brain cross
carried up the spinal cord to the brain. Motor
NOT FOR SALE OR DISTRIB
NOT FOR SALE OR DISTRIBUTION
to the right side of the spinal cord and initiate a
(efferent) impulses travel from the brain down
response to the right side of the body. Because
the spinal cord and exit from motor nerve roots
of this crossover effect, damage on one side of
(anterior roots) at the front of the spinal cord.
the brain typically causes manifestations on the
Motor nerve fibers then carry impulses to the
opposite
side
of
the
body.
voluntary muscles
of the&body.
© Jones & Bartlett Learning, LLC
© Jones
Bartlett Learning, LLC
The
inner
gray
matter
of
the
spinal
cord,
which
Many
types
of
neurons
work
together
transmit
NOT FOR SALE OR DISTRIBUTION
NOT FOR SALE
ORtoDISTRIBUTION
is composed of cell bodies and unmyelinated neuimpulses through the spinal cord. Sensory impulses
rons, acts as a coordinating center for reflex and
entering the spinal cord at the lumbar region are
other activities, such as voluntary movements and
relayed vertically to the brain through a number
control of internal functions. A reflex center in
of connecting sensory neurons. Motor impulses
Jones & BartletttheLearning,
LLC
© Jones
& brain
Bartlett
LLChowever,
gray matter of
the spinal cord is where senfrom the
to the Learning,
peripheral nerves,
soryDISTRIBUTION
and motor neurons connect; this part of the
conducted
through
two separate categories of
OT FOR SALE OR
NOTare
FOR
SALE
OR DISTRIBUTION
spinal cord serves as a center for spinal reflexes.
motor neurons. Upper motor neurons originate
A reflex can be defined as an automatic response
in the brain and are contained entirely within the
to a given stimulus. Spinal reflexes control not
central nervous system. Lower motor neurons,
only muscle reflexes but also the reflexes of inalthough originating in the central nervous sys© Jones & Bartlett Learning, LLC
©peripheral
Jones nerves
& Bartlett Learning
ternal organs.
tem, have fibers extending to the
NOT
FOR
SALE
OR DISTRIB
NOT
FOR
SALE
OR
DISTRIBUTION
The gray matter within the spinal cord resembles
in voluntary muscles. Alteration of function
of
the letter “H.” The projections of the H are named
either upper or lower motor neurons can generally
according to the direction to which they project.
affect the voluntary muscles. The location of the
The posterior horns extend toward the back, and
alteration of function determines the nature of the
the anterior
horns project
toward the
front. Ceremanifestations.
© Jones
& Bartlett
Learning,
LLC
© Jones & Bartlett Learning, LLC
brospinal fluid, which nourishes and protects the
NOT spinal
FOR cord,
SALE
OR
DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
fills both the central canal, located
Structure and Function of the Peripheral
within the center of the gray matter, and the subNervous System
arachnoid space surrounding the outer portion of
A nerve is a bundle of fibers outside the central
the spinal cord.
nervous
thatLearning,
transmits information
Motor
(efferent)
impulses
originate
in
the
moJones & Bartlett Learning, LLC
© Jones
& system
Bartlett
LLC between the central nervous system and various
tor cortex of the brain, extend down the spinal cord
OT FOR SALE OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
parts of the body. The peripheral nervous systhrough descending tracts, and exit through motor
tem consists of all nerves that extend from the
spinal nerve roots that extend through openings
brain and spinal cord. To function effectively,
between the vertebrae that surround the spinal
the peripheral nerves must be connected to the
cord. Sensory (afferent) impulses from the body
central nervous system. Some©
peripheral
enter the spinal
cord through
spinal nerveLearning,
roots that
© Jones
& Bartlett
LLC
Jones nerves
& Bartlett Learning
connect
directly
to
the
brain
(cranial
nerves);
also extend NOT
through
openings
between
vertebrae
NOT FOR SALE OR DISTRIB
FOR SALE OR DISTRIBUTION
others connect directly to the spinal cord (spinal
and then travel up ascending tracts in the spinal
nerves). Cranial and spinal nerves are essential
cord to the brain.
links between the rest of the body and the cenSpinal nerve roots are named for the vertetral nervous system.
bral level from which they exit. For example,
© Jones
& Bartlett
LLC
© Jones
& Bartlett
Learning,
LLC
The 12 pairs
of peripheral
nerves that
connect
the nerve
roots thatLearning,
leave the spinal
cord at the
NOT cervical
FOR SALE
ORlabeled
DISTRIBUTION
NOT
FORdirectly
SALEtoOR
DISTRIBUTION
and transmit
messages
the brain
are
level are
C1 through C8, and
called cranial nerves. Some cranial nerves contain
the nerve roots that leave at the thoracic level
only sensory fibers, whereas others contain both
are labeled T1 through T12 (see Figure 3-5).
sensory and motor fibers. Cranial nerves mediate
The sensory (afferent) nerve fibers from outside
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 39
28/10/16 12:18 PM
© Jones & Bartlett Learning, LLC
Jones & Bartlett Learning, LLC
40 Chapter
3 • Introduction
to
the
Structure
and Function
of the Nervous
System
NOT
FOR SALE
OR DISTRIBUTION
OT FOR SALE OR DISTRIBUTION
Figure 3-5 Spinal Nerves
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
Cervical
nerves
(8 pairs)
Cervical
cord
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
Thoracic
cord
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR
DISTRIBUTION
Cauda
Thoracic
nerves
(12 pairs)
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
© JonesLumbar
& Bartlett Learning, LLC
nerves
NOT FOR
SALE OR DISTRIBUTION
(5 pairs)
equina
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
Sacral
nerves
(5 pairs)
© Jones & Bartlett Learning, LLC
Coccygeal
NOT FOR SALE OR DISTRIBUTION
nerve
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
many aspects of sensation and muscular activity in
and around the head and neck. Cranial nerves and
their related functions are described in Table 3-2.
© JonesThe
& Bartlett
LLCthat con31 pairs ofLearning,
peripheral nerves
NOT nect
FOR
DISTRIBUTION
andSALE
transmitOR
messages
directly to the spinal
cord are called spinal nerves. Each nerve divides
and then subdivides into a number of branches.
Nerves at each level travel to specific parts of the
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
body, conveying information between those areas
and the central nervous system. Spinal nerves and
their related functions are described in Figure 3-5.
© Jones
& Bartlett
Learning, LLC
Nerves control
both voluntary
and involuntary
FOR
SALE
OR DISTRIBUTION
functions inNOT
the body.
Nerves
that control
voluntary functions (such as movement of the muscles
in the extremities) are called somatic nerves.
Nerves that are concerned with the control of
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 40
28/10/16 12:18 PM
© Jones & Bartlett Learning, LLC
Bibliography 41
NOT FOR SALE OR DISTRIBUTION
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
Table 3-2 Cranial Nerves and Related Functions
Cranial Nerve
Area of Function
II. Optic
Vision
III. Oculomotor
Movement of eye muscles
IV. Trochlear
Eyelids
V. Trigeminal
Sensation in head, face, and teeth, motor activity of chewing
© Jones & Bartlett Learning, LLC
I. Olfactory
Smell
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
© Jones & Bartlett Learning, LLC
© Jones & Bartlett Learning, LLC
VI. Abducens
Pupil dilation, focusing of lens
NOT VII. FORFacial
SALE OR DISTRIBUTION
NOT FOR SALE OR DISTRIBUTION
Taste, sensation of external ear, control of salivary glands, tears, muscles in
facial expression
VIII. Vestibulocochlear
Sensation of sound, balance, orientation of head
IX. Glossopharyngeal
Swallowing, sensation of pain, taste, touch from tongue and throat
Jones & BartlettX. Vagus
Learning, LLC
OT FOR SALE OR
DISTRIBUTION
XI. Accessory
©speech,
Jones
& Bartlett
Learning,
LLC
respiratory
function, gland
functions
Heartbeat, digestion,
swallowing,
FOR muscles
SALEofOR
DISTRIBUTION
Movement of head NOT
and shoulders,
pharynx
and larynx in throat,
production of voice sounds
Tongue movement, speech, swallowing
XII. Hypoglossal
© Jones & Bartlett Learning, LLC
© Jones & Bartlett Learning
involuntaryNOT
functions
are part
of a subcategory
of
The sympathetic nervous system
acNOT becomes
FOR SALE
OR DISTRIB
FOR
SALE
OR DISTRIBUTION
the peripheral nervous system called the autonomic
tive during periods of stress and in emergencies.
nervous system.
It prepares the body for action, deepening respiThe autonomic nervous system integrates the
rations, making the heart beat faster, dilating the
work of vital organs, such as the heart and lungs.
pupils, stimulating production of stress hormones,
© Jones
& Bartlett
LLC
© Jones
& Bartlett
Learning,
LLC
Its primary
functionLearning,
is to coordinate
the activity
and increasing
blood supply
to the large
muscles
NOT of
FOR
SALE
DISTRIBUTION
internal
organsOR
so that
they can make adaptive
of the body.NOT FOR SALE OR DISTRIBUTION
responses to changing external situations, thereby
In contrast, the parasympathetic nervous sysmaintaining internal equilibrium. Nerve fibers
tem dominates when the body is a rest. It activates
monitor the activities of internal organs as well as
those mechanisms that focus on body conservation,
changes in the external environment. When changes
such as decreasing the heart rate and constricting
Jones & BartlettareLearning,
© Jones
& Bartlett
Learning,
LLCnervous
necessary toLLC
maintain internal homeostasis
the pupils
of the eye. The
parasympathetic
OT FOR SALE OR
DISTRIBUTION
NOTsystem
FOR isSALE
DISTRIBUTION
(equilibrium)
or to protect the body, the autonomic
also an OR
important
component of sexual
nervous system stimulates an immediate, involunarousal in both males and females.
tary response. For example, in response to a speck
of dust in the eye, tears are produced; in response
Bibliography
to a fearful situation, the heart beats faster.
© Jones & Bartlett Learning, LLC
© Jones & Bartlett Learning
The autonomic nervous system is divided into
Falvo, R. E. (2001). Human physiology: Physiology 201 core
NOT FOR SALE OR DISTRIBUTION
curriculum. Champaign, IL: Stipes.NOT FOR SALE OR DISTRIB
two subsystems:
Sherwood, L. (2007). Human physiology: From cells to systems.
(6th ed.). Australia: Thomson Brooks/Cole
• The sympathetic nervous system
• The parasympathetic nervous system
two systems
work both together
© JonesThese
& Bartlett
Learning,
LLC and in
to control
organs and regulate
NOT opposition
FOR SALE
OR internal
DISTRIBUTION
their function. Hormones and emotions can affect
both systems.
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
Tortora, G. J., & Derrickson, B. H. (Eds.). (2011). Principles
of anatomy and physiology (13th ed.). Hoboken, NJ:
& Bartlett Learning,
John Wiley ©
andJones
Sons
LLC
NOT
DISTRIBUTION
Widmaier, E., Raff,
H., FOR
& Strang,SALE
K. (Eds.).OR
(2010).
Vander’s
human physiology: The mechanisms of body function.
New York, NY: McGraw-Hill.
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 41
28/10/16 12:18 PM
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
Jones & Bartlett Learning, LLC
OT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning
NOT FOR SALE OR DISTRIB
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC
NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION
9781284105407_CH03_Falvo.indd 42
28/10/16 12:18 PM