Download Chapter_013

Chapter 13
Central Nervous System
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 1
Coverings of the Brain
and Spinal Cord

Two protective coverings (Figure 13-2):

Outer covering is bone; cranial bones encase the
brain, and vertebrae encase the spinal cord
(Figure 13-1)

Inner covering is the meninges; the meninges of
the cord continue inside the spinal cavity beyond
the end of the spinal cord
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 2
Coverings of the Brain
and Spinal Cord

Meninges—three membranous layers (Figure 13-3)

Dura mater—strong, white fibrous tissue; outer layer of meninges
and inner periosteum of the cranial bones; has three important
extensions
• Falx cerebri

Projects downward into the longitudinal fissure between the two cerebral
hemispheres

Dural sinuses—function as veins, collecting blood from brain tissues for
return to the heart

Superior sagittal sinus—one of several dural sinuses
• Falx cerebelli—separates the two hemispheres of the cerebellum
• Tentorium cerebelli—separates the cerebellum from the cerebrum

Arachnoid mater—delicate, cobwebby layer between the dura
mater and pia mater
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 3
Coverings of the Brain
and Spinal Cord

Meninges—three membranous layers (cont.)

Pia mater—innermost, transparent layer; adheres
to the outer surface of the brain and spinal cord;
contains blood vessels; beyond the spinal cord,
forms a slender filament called filum terminale; at
level of sacrum, blends with dura mater to form a
fibrous cord that disappears into the periosteum of
the coccyx
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 4
Coverings of the Brain
and Spinal Cord

Several spaces exist between and around the
meninges
• Epidural space—located between the dura mater and
inside the bony covering of the spinal cord; contains a
supporting cushion of fat and other connective tissues
(virtually absent around brain because dura is continuous
with periosteum of bone)
• Subdural space—located between the dura mater and
arachnoid mater; contains lubricating serous fluid
• Subarachnoid space—located between the arachnoid
and pia mater; contains a significant amount of
cerebrospinal fluid
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 5
Cerebrospinal Fluid


Functions

Provides a supportive, protective cushion

Reservoir of circulating fluid, which is monitored
by the brain to detect changes in the internal
environment
Fluid spaces

Cerebrospinal fluid—found within the
subarachnoid space around the brain and spinal
cord and within the cavities and canals of the brain
and spinal cord
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 6
Cerebrospinal Fluid

Fluid spaces (cont.)

Ventricles—fluid-filled spaces within the brain; four
ventricles within the brain (Figure 13-4)
• First and second ventricles (lateral)—one located in each
hemisphere of the cerebrum
• Third ventricle—thin, vertical pocket of fluid below and
medial to the lateral ventricles
• Fourth ventricle—tiny, diamond-shaped space where the
cerebellum attaches to the back of the brainstem
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 7
Cerebrospinal Fluid

Formation and circulation of cerebrospinal
fluid (Figure 13-5)

Occurs by separation of fluid from blood in the
choroid plexuses
• Fluid from the lateral ventricles seeps through the
interventricular foramen (of Monro) into the third ventricle
• From the third ventricle, fluid goes through the cerebral
aqueduct into the fourth ventricle
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 8
Cerebrospinal Fluid

Formation and circulation of cerebrospinal
fluid (cont.)
• From the fourth ventricle, fluid goes to two different
areas:

Some fluid flows directly into the central canal of the spinal
cord

Some fluid leaves the fourth ventricle through openings in
its roof into the cisterna magna, a space that is continuous
with the subarachnoid space
• Fluid circulates in the subarachnoid space and then is
absorbed into venous blood through the arachnoid villi
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 9
Spinal Cord

Structure of the spinal cord (Figure 13-6)

Lies within the spinal cavity and extends from the
foramen magnum to the lower border of the first
lumbar vertebra

Oval cylinder that tapers slightly from above
downward

Two bulges, one in the cervical region and one in
the lumbar region

Anterior median fissure and posterior median
sulcus are two deep grooves; anterior fissure is
deeper and wider
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 10
Spinal Cord

Structure of the spinal cord (cont.)

Nerve roots
• Fibers of dorsal nerve root

Carry sensory information into the spinal canal

Dorsal root ganglion—cell bodies of unipolar, sensory neurons make
up a small region of gray matter in the dorsal nerve root
• Fibers of ventral nerve root

Carry motor information out of the spinal cord

Cell bodies of multipolar, motor neurons are in the gray matter of the
spinal cord

Interneurons are located in the spinal cord’s gray matter core

Spinal nerve—a single mixed nerve on each side of the spinal cord
where the dorsal and ventral nerve roots join together
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 11
Spinal Cord

Structure of the spinal cord (cont.)

Cauda equina—bundle of nerve roots extending (along with the
filum terminale) from the conus medullaris (inferior end of spinal cord)
(Figure 13-7)

Gray matter
• Columns of gray matter extend the length of the cord
• Consists predominantly of cell bodies of interneurons and motor neurons
• In transverse section, looks like an H with the limbs being called the anterior,
posterior, and lateral horns of gray matter; cross-bar of H is the gray commissure

White matter
• Surrounds the gray matter and is subdivided in each half of the cord into three
funiculi: anterior, posterior, and lateral white columns
• Each funiculus consists of a large bundle of axons divided into tracts
• Names of spinal tracts indicate the location of the tract, the structure in which the
axons originate, and the structure in which they terminate
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 12
Spinal Cord

Functions of the spinal cord

Provides conduction routes to and from the brain
• Ascending tracts—conduct impulses up the cord to the brain
• Descending tracts—conduct impulses down the cord from
the brain
• Bundles of axons compose all tracts
• Tracts are both structural and functional organizations
of nerve fibers:

Structural—all axons of any one tract originate in the same
structure and terminate in the same structure

Functional—all axons that compose one tract serve one general
function
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 13
Spinal Cord

Functions of the spinal cord (cont.)
• Important ascending (sensory) tracts (Figure 13-8)

Lateral spinothalamic tracts—crude touch, pain, and
temperature

Anterior spinothalamic tracts—crude touch, pressure

Fasciculi gracilis and cuneatus—discriminating touch and
conscious kinesthesia

Spinocerebellar tracts—subconscious kinesthesia

Spinotectal—touch related to visual reflexes
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 14
Spinal Cord

Functions of the spinal cord (cont.)
• Important descending (motor) tracts (Figure 13-8)

Lateral corticospinal tracts—voluntary movements on opposite
side of the body

Anterior corticospinal tracts—voluntary movements on same side of body

Reticulospinal tracts—maintain posture during movement

Rubrospinal tracts—transmit impulses that coordinate body movements
and maintenance of posture

Tectospinal tracts—head and neck movements during visual reflexes

Vestibulospinal tracts—coordination of posture and balance
• Spinal cord—reflex center for all spinal reflexes; spinal reflex
centers are located in the gray matter of the cord
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 15
The Brain

Structures of the brainstem (Figures 13-9 and 13-10)

Medulla oblongata
• Lowest part of the brainstem
• Part of the brain that attaches to spinal cord, located just above the
foramen magnum
• A few centimeters in length and separated from the pons above by a
horizontal groove
• Composed of white matter and a network of gray and white matter
called the reticular formation network
• Pyramids—two bulges of white matter located on the ventral side of
the medulla; formed by fibers of the pyramidal tracts
• Olive—oval projection located lateral to the pyramids
• Nuclei—clusters of neuron cell bodies located in the reticular
formation
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 16
The Brain

Structures of the brainstem (cont.)

Pons
• Located above the medulla and below the midbrain
• Composed of white matter and reticular formation

Midbrain
• Located above the pons and below the cerebrum; forms the midsection of the brain
• Composed of white tracts and reticular formation
• Extending divergently through the midbrain are cerebral peduncles; conduct
impulses between the midbrain and cerebrum
• Corpora quadrigemina—landmark in midbrain

Made up of two inferior colliculi and two superior colliculi

Forms the posterior, upper part of the midbrain that lies just above the cerebellum

Inferior colliculus—contains auditory centers

Superior colliculus—contains visual centers
• Red nucleus and substantia nigra—clusters of cell bodies of neurons involved in
muscular control
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 17
The Brain

Functions of the brainstem

Performs sensory, motor, and reflex functions

Spinothalamic tracts—important sensory tracts
that pass through the brainstem

Fasciculi cuneatus and gracilis and spinoreticular
tracts—sensory tracts whose axons terminate in
the gray matter of the brainstem

Corticospinal and reticulospinal tracts—two of the
major tracts present in the white matter of the
brainstem
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 18
The Brain

Functions of the brainstem (cont.)

Nuclei in medulla—contain reflex centers
• Of primary importance—cardiac, vasomotor, and
respiratory centers
• Nonvital reflexes—vomiting, coughing, sneezing, etc.

Pons—contains reflexes mediated by fifth, sixth,
seventh, and eighth cranial nerves and
pneumotaxic centers that help regulate respiration

Midbrain—contains centers for certain cranial
nerve reflexes
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 19
The Brain

Structure of the cerebellum (Figure 13-11)

Second largest part of the brain—contains more neurons
than the rest of the nervous system

Located just below the posterior portion of the cerebrum;
transverse fissure separates these two parts of the brain

Gray matter makes up the cortex, and white matter
predominates in the interior

Arbor vitae—internal white matter of the cerebellum;
distinctive pattern similar to the veins of a leaf

Cerebellum has numerous sulci and delicate, parallel
gyri (folia)
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 20
The Brain

Structure of the cerebellum (cont.)


Consists of the cerebellar hemispheres and the vermis
Internal white matter—composed of short and long tracts
• Shorter tracts—conduct impulses from neuron cell bodies located in the
cerebellar cortex to neurons whose dendrites and cell bodies compose nuclei
located in the interior of the cerebellum
• Longer tracts—conduct impulses to and from the cerebellum; fibers enter or
leave by way of three pairs of peduncles




Inferior cerebellar peduncles—composed chiefly of tracts entering the cerebellum from
the medulla and cord
Middle cerebellar peduncles—composed almost entirely of tracts entering the
cerebellum from the pons
Superior cerebellar peduncles—composed principally of tracts leading from dentate
nuclei in the cerebellum through the red nucleus of the midbrain to the thalamus
Dentate nuclei
• Important pair of cerebellar nuclei, one of which is located in each hemisphere
• Nuclei connected with thalamus and with motor areas of the cerebral cortex by
tracts
• By means of the tracts, cerebellar impulses influence the motor cortex, and the
motor cortex influences the cerebellum
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 21
The Brain

Functions of the cerebellum

Cerebellum compares the motor commands of the cerebrum to the
information coming from proprioceptors in the muscle; impulses travel
from the cerebellum to both the cerebrum and muscles to coordinate
movements to produce the intended action (Figure 13-12)

General functions
• Acts with cerebral cortex to produce skilled movements by coordinating
the activities of groups of muscles
• Controls skeletal muscles to maintain balance
• Controls posture; operates at subconscious level to smooth movements
and make movements efficient and coordinated
• Processes sensory information; complements and assists various
functions of the cerebrum
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 22
The Brain

Diencephalon (Figure 13-13)

Located between the cerebrum and the midbrain

Consists of several structures located around the third ventricle:
thalamus, hypothalamus, optic chiasma, pineal gland, and several
others

Thalamus
• Dumbbell-shaped mass of gray matter made up of many nuclei
• Each lateral mass forms one lateral wall of the third ventricle
• Intermediate mass—extends through the third ventricle and joins the
two lateral masses
• Geniculate bodies—two of the most important groups of nuclei
comprising the thalamus; located in posterior region of each lateral
mass; play role in processing auditory and visual input
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 23
The Brain

Thalamus (cont.)
• Serves as a major relay station for sensory impulses on their way to
the cerebral cortex
• Performs the following primary functions:

Plays two parts in mechanism responsible for sensations:
– Impulses produce conscious recognition of the crude, less critical sensations of
pain, temperature, and touch
– Neurons relay all kinds of sensory impulses, except possibly olfactory, to the
cerebrum

Plays part in the mechanism responsible for emotions by associating
sensory impulses with feeling of pleasantness and unpleasantness

Plays part in arousal mechanism

Plays part in mechanisms that produce complex reflex movements
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 24
The Brain

Diencephalon (cont.)

Hypothalamus
• Consists of several structures that lie beneath the thalamus
• Forms floor of the third ventricle and lower part of lateral walls
• Prominent structures found in the hypothalamus

Supraoptic nuclei—gray matter located just above and on either
side of the optic chiasma

Paraventricular nuclei—located close to the wall of the third
ventricle

Mamillary bodies—posterior part of hypothalamus, involved
with olfactory sense
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 25
The Brain

Hypothalamus (cont.)
• Infundibulum—the stalk leading to the posterior lobe
of the pituitary gland
• Small but functionally important area of the brain,
performs many functions of greatest importance for
survival and enjoyment
• Links mind and body
• Links nervous system to endocrine system
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 26
The Brain

Hypothalamus (cont.)
• Summary of hypothalamic functions

Regulator and coordinator of autonomic activities

Major relay station between the cerebral cortex and lower
autonomic centers; crucial part of the route by which emotions
can express themselves in changed bodily functions

Synthesizes hormones secreted by posterior pituitary and plays
an essential role in maintaining water balance

Some neurons function as endocrine glands

Plays crucial role in arousal mechanism

Crucial part of mechanism regulating appetite

Crucial part of mechanism maintaining normal body
temperature
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 27
The Brain

Diencephalon (cont.)

Pineal gland
• Located just above the corpora quadrigemina of the midbrain
• Involved in regulating the body’s biological clock (Figure 13-14)
• Produces melatonin as a “timekeeping hormone”

Melatonin is made from the neurotransmitter serotonin

Melatonin levels increase when sunlight is absent and decreases
when sunlight is present, thus regulating the circadian (daily)
biological clock (Figure 13-15)

Melatonin is the “sleep hormone”
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 28
The Brain

Structure of the cerebrum

Cerebral cortex
• Largest and uppermost division of the brain; consists of
right and left cerebral hemispheres; each hemisphere is
divided into five lobes (Figure 13-16):

Frontal lobe

Parietal lobe

Temporal lobe

Occipital lobe

Insula (island of Riel)
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 29
The Brain

Cerebral cortex (cont.)
• Cerebral cortex—outer surface made up of six layers of
gray matter
• Gyri—convolutions; some are named: precentral gyrus,
postcentral gyrus, cingulate gyrus, and hippocampal
gyrus
• Sulci—shallow grooves
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 30
The Brain

Cerebral cortex (cont.)
• Fissures—deeper grooves, divide each cerebral
hemisphere into lobes; four prominent cerebral fissures

Longitudinal fissure—deepest fissure; divides cerebrum
into two hemispheres

Central sulcus (fissure of Rolando)—groove between
frontal and parietal lobes

Lateral fissure (fissure of Sylvius) —groove between
temporal lobe below and parietal lobes above; island of
Reil lies deep in lateral fissure

Parietooccipital fissure—groove that separates occipital
lobe from parietal lobes
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 31
The Brain

Structure of the cerebrum (cont.)

Cerebral tracts and basal nuclei
• Basal nuclei—islands of gray matter located deep inside
the white matter of each hemisphere (Figure 13-18);
include the following:

Caudate nucleus

Lentiform nucleus—consists of putamen and pallidum

Amygdaloid nucleus
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 32
The Brain

Structure of the cerebrum (cont.)

Cerebral tracts and basal nuclei (cont.)
• Cerebral tracts make up cerebrum’s white matter; there
are three types (Figure 13-17):



Projection tracts—extensions of the sensory spinothalamic
tracts and motor corticospinal tracts
Association tracts—most numerous cerebral tracts; extend
from one convolution to another in the same hemisphere
Commissural tracts—extend from one convolution to a
corresponding convolution in the other hemisphere;
compose the corpus callosum and anterior and posterior
commissures
• Corpus striatum—composed of caudate nucleus, internal
capsule, and lentiform nucleus
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 33
The Brain

Functions of the cerebral cortex

Functional areas of the cortex—certain areas of the cerebral
cortex predominantly engage in one particular function
(Figures 13-19 and 13-20)
• Postcentral gyrus—mainly general somatic sensory area;
receives impulses from receptors activated by heat, cold, and
touch stimuli
• Precentral gyrus—chiefly somatic motor area; impulses from
neurons in this area descend over motor tracts and stimulate
skeletal muscles
• Transverse gyrus—primary auditory area
• Occipital lobe—primary visual areas
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 34
The Brain

Functions of the cerebral cortex (cont.)

Sensory functions of the cortex
• Somatic senses—sensations of touch, pressure, temperature,
proprioception, and similar perceptions that require complex
sensory organs
• Cortex contains a “somatic sensory map” of the body
• Information sent to primary sensory areas is relayed to
sensory association areas, as well as to other parts of the
brain
• The sensory information is compared and evaluated, and the
cortex integrates separate bits of information into whole
perceptions
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 35
The Brain

Motor functions of the cortex
• For normal movements to occur, many parts of the nervous
system must function
• Precentral gyrus—primary somatic motor area; controls
individual muscles
• Secondary motor area—in the gyrus immediately anterior to
the precentral gyrus; activates groups of muscles
simultaneously
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 36
The Brain

Integrative functions of the cortex
• Consciousness (Figure 13-21)

State of awareness of one’s self, one’s environment, and other beings

Depends on excitation of cortical neurons by impulses conducted to them
by the reticular activating system

There are two current concepts about the reticular activating system:
– Functions as the arousal system for the cerebral cortex
– Its functioning is crucial for maintaining consciousness
• Language

Ability to speak and write words and ability to understand spoken and written
words

Speech centers—areas in the frontal, parietal, and temporal lobes

Left cerebral hemisphere contains speech centers in approximately 90%
of the population; in the remaining 10%, contained in either the right
hemisphere or both

Aphasias—caused by lesions in speech centers
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 37
The Brain

Integrative functions of the cortex (cont.)
• Emotions (Figure 13-22)


Subjective experiencing and objective expressing of emotions involve
functioning of the limbic system
Limbic system—also known as the “emotional brain”
– Most structures of limbic system lie on the medial surface of the cerebrum; they are
the cingulate gyrus and the hippocampus
– Have primary connections with other parts of the brain, such as thalamus, fornix,
septal nuclei, amygdaloid nucleus, and hypothalamus
• Memory





One of the major human mental activities
Cortex is capable of storing and retrieving both short- and
long-term memory
Temporal, parietal, and occipital lobes are among the areas responsible for
short- and long-term memory
Engrams—structural traces in the cerebral cortex that comprise long-term
memories
Cerebrum’s limbic system plays a key role in memory
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 38
The Brain

Hemisphericity—specialization of cerebral hemispheres
• Right and left hemispheres of the cerebrum specialize in
different functions; however, both sides of a normal person’s
brain communicate with each other to accomplish complex
functions
• Left hemisphere is responsible for the following:

Language functions

Dominating control of certain hand movements
• Right hemisphere is responsible for the following:

Perception of certain kinds of auditory material

Tactual perception

Perceiving and visualizing spatial relationships
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 39
Somatic Sensory Pathways
in the Central Nervous System


For the cerebral cortex to perform its sensory functions,
impulses must first be conducted to the sensory areas
by sensory pathways (Figure 13-24)
Three main pools of sensory neurons:


Primary sensory neurons—conduct impulses from the periphery
to the central nervous system
Secondary sensory neurons
• Conduct impulses from cord or brainstem to thalamus
• Dendrites and cell bodies are located in gray matter of cord and brainstem
• Axons ascend in ascending tracts up cord and through the brainstem, and terminate in
thalamus, where they synapse with dendrites or cell bodies of tertiary sensory neurons

Tertiary sensory neurons
• Conduct impulses from thalamus to the postcentral gyrus of parietal lobe
• Bundle of axons of tertiary sensory neurons form thalamocortical tracts
• Extend through internal capsule to cerebral cortex
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 40
Somatic Sensory Pathways
in the Central Nervous System

Sensory pathways to the cerebral cortex are crossed

Two sensory pathways conduct impulses that
produce sensations of touch and pressure:

Medial lemniscal system
• Consists of tracts that make up the fasciculi cuneatus and
gracilis, and the medial lemniscus
• Axons of secondary sensory neurons make up medial
lemniscus
• Functions—transmit impulses that produce discriminating touch
and pressure sensations and kinesthesia

Spinothalamic pathway—functions are crude touch and
pressure sensations
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 41
Somatic Motor Pathways
in the Central Nervous System

For the cerebral cortex to perform its motor functions,
impulses are conducted from its motor areas to skeletal
muscles by somatic motor pathways

Consist of motor neurons that conduct impulses from the
central nervous system to skeletal muscles; some motor
pathways are extremely complex, and others are very
simple

Principle of the final common path—cardinal principle
about somatic motor pathways; only one final common
path, the motor neuron from the anterior gray horn of the
spinal cord, conducts impulses to skeletal muscles
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 42
Somatic Motor Pathways
in the Central Nervous System

Two methods used to classify somatic motor pathways:

Divides pathways into pyramidal and extrapyramidal tracts (Figure 13-25)
• Pyramidal tracts—also known as corticospinal tracts


Approximately three quarters of the fibers decussate in the medulla and extend down
the cord in the crossed corticospinal tract located on the opposite side of the spinal
cord in the lateral white column
Approximately one quarter of the fibers do not decussate but extend down the same
side of the spinal cord as the cerebral area from which they came
• Extrapyramidal tracts—much more complex than pyramidal tracts






Consist of all motor tracts from the brain to the spinal cord anterior horn motor
neurons except the corticospinal tracts
Within the brain, consist of numerous relays of motor neurons between motor areas
of cortex, basal nuclei, thalamus, cerebellum, and brainstem
Within the spinal cord, some important tracts are the reticulospinal tracts
Conduction by extrapyramidal tracts plays a crucial part in producing large, automatic
movements
Conduction by extrapyramidal tracts plays an important part in emotional expressions
Motor program—set of coordinated commands that control the programmed motor
activity mediated by extrapyramidal pathways (Figure 13-26)
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 43
Cycle of Life:
Central Nervous System

The development and degeneration of the central
nervous system is the most obvious functional change
over the life span

Development of the brain and spinal cord begins
in the womb

Lack of development in the newborn is evidenced by
lack of complex integrative functions

Language

Complex memory

Comprehension of spatial relationships

Complex motor skills
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 44
Cycle of Life:
Central Nervous System

Complex functions develop by adulthood

Late adulthood—tissues degenerate

Profound degeneration—unable to perform
complex functions

Milder degeneration—temporary memory lapse or
difficulty with complex motor tasks
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 45
The Big Picture: The Central Nervous
System and the Whole Body

Central nervous system—ultimate regulator
of the body; essential to survival

Able to integrate bits of information from all
over the body, make sense of them, and
make decisions
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 46