Central Nervous System

Содержание

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Introduction Analogies; telephone switchboard; computer; miracle A fantastically complex and flexible

Introduction

Analogies; telephone switchboard; computer; miracle
A fantastically complex and flexible biological

organ
Cephalization become more apparent in higher order species
Increase in the neurons at the rostral end of the CNS
Highest level of cephalization is found in humans
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The Brain The unimpressive appearance of the human brain give few

The Brain

The unimpressive appearance of the human brain give few hints

of its abilities
It is about two handfuls of delicate pinkish gray tissue
Wrinkled surface
Consistency of cold oatmeal

Brain
stem

Cerebellum

Cerebral
hemisphere

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The Brain Average adult male’s brain weighs about 1600 g (3.5

The Brain

Average adult male’s brain weighs about 1600 g (3.5 pounds)
Average

adult female’s brain weighs about 1450 g
Brain size represents a proportional difference in body size
Brain size is not correlated to intelligence but is related to the complexity of the neural connections within the brain
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Embryonic Development Starting in the third week of pregnancy, the ectoderm

Embryonic Development

Starting in the third week of pregnancy, the ectoderm thickens

along the dorsal midline axis of the embryo to form a neural plate
The neural plate eventually gives rise to all neural tissues
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Embryonic Development The neural plate then invaginates, forming a groove flanked by neural folds

Embryonic Development

The neural plate then invaginates, forming a groove flanked by

neural folds
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Development of Neural Tube As the groove deepens the superior edges

Development of Neural Tube

As the groove deepens the superior edges of

the neural folds fuse, forming the neural tube
The tube then detaches from the surface ectoderm and assumes a deeper position in the embryo
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Development of Neural Tube The neural tube is formed by the

Development of Neural Tube

The neural tube is formed by the fourth

week of pregnancy and differentiates rapidly into the CNS
The brain forms anteriorly and the spinal cord posteriorly
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Development of Neural Tube Small groups of neural fold cells migrate

Development of Neural Tube

Small groups of neural fold cells migrate laterally

and locate between the surface ectoderm and the neural tube to forming the neural crest
The neural crest gives rise to sensory neurons and some autonomic neurons destined to reside in ganglia
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Development of Neural Tube As soon as the neural tube is

Development of Neural Tube

As soon as the neural tube is formed,

its anterior end begins to expand more rapidly than the remaining portion
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Primary Brain Vesicles Constrictions in the neural tube appear to mark

Primary Brain Vesicles

Constrictions in the neural tube appear to mark off

the three primary brain vesicles
Prosencephalon
(forebrain)
Mesencephalon
(midbrain)
Rhombencephalon
(hindbrain)
The remainder of the neural tube becomes the spinal cord
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Secondary Brain Vesicles By the fifth week, the five brain regions

Secondary Brain Vesicles

By the fifth week, the five brain regions of

the secondary brain vesicles are evident
The forebrain has divided
Telencephalon
Diencephalon
The midbrain remains undivided
The hindbrain has constricted to form
Metencephalon
Myelencephalon
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Secondary Brain Vesicles Each of the five secondary brain vesicles develops

Secondary Brain Vesicles

Each of the five secondary brain vesicles develops rapidly

to produce the major structures of the adult brain
The greatest change occurs in the telencephalon which sprouts two large swellings which project anteriorly
These paired expansions become the cerebral hemispheres known collectively as the cerebrum
Hemispheres house ventricles
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Secondary Brain Vesicles Various areas of the diencephalon specialize to form Hypothalamus Thalamus Epithalamus

Secondary Brain Vesicles

Various areas of the diencephalon specialize to form
Hypothalamus
Thalamus
Epithalamus

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Secondary Brain Vesicles The mesencephalon develops into Midbrain Brain stem

Secondary Brain Vesicles

The mesencephalon develops into
Midbrain
Brain stem

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Secondary Brain Vesicles Various areas of the Metencephalon specialize to form Brain stem Pons Cerebellum

Secondary Brain Vesicles

Various areas of the Metencephalon specialize to form
Brain stem
Pons
Cerebellum

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Secondary Brain Vesicles Various areas of the Myelencephalon specialize to form

Secondary Brain Vesicles

Various areas of the Myelencephalon specialize to form
Brain stem
Medulla

oblongata
All the midbrain and hindbrain structures, with the exception of the cerebellum, form portions of the brain stem
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Adult Neural Canal Regions The central canal of the neural tube

Adult Neural Canal Regions

The central canal of the neural tube enlarge

in four areas to form the fluid filled ventricles
Telencephalon
Lateral ventricles
Superior portion of 3rd
Diencephalon
Most of third ventricle
Mesencephalon
Cerebral aqueduct
Metencephalon
Fourth ventricle
Myelencephalon
Fourth ventricle
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Development of Flexures During this period of rapid brain growth change

Development of Flexures

During this period of rapid brain growth change is

also occurring in the relative position of its parts
Because the brain’s growth is restricted by the skull, midbrain and cervical flexures develop by the fifth week which bend the forebrain toward the brain stem
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Effects of Space Restriction A second consequence of restricted space is

Effects of Space Restriction

A second consequence of restricted space is that

the cerebral hemispheres are forced to take a horseshoe shaped course posteriorly and laterally
Development of the cerebral hemispheres at 13 weeks
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Effects of Space Restriction As a result the hemispheres grow back

Effects of Space Restriction

As a result the hemispheres grow back over

and almost completely envelop the diencephalon and midbrain
The cerebral hemispheres at 26 weeks
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Effects of Space Restriction Continued growth of the cerebral hemispheres causes

Effects of Space Restriction

Continued growth of the cerebral hemispheres causes their

surfaces to crease and fold
Folding results in convolutions which increase surface area and allow some 1012 neurons to occupy the limited space within the skull
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Effects of Space Restriction The wrinkling of the hemispheres may result

Effects of Space Restriction

The wrinkling of the hemispheres may result from

tension on the young axons as they become arranged in a way that minimizes the length of the interconnections they form among the various parts of the cerebrum
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Regions of the Brain The four main regions of the brain

Regions of the Brain

The four main regions of the brain are:
Cerebral

hemi- spheres
Diencephalon
Thalamus
Hypothalamus
Epithalamus
Brain stem
Midbrain
Pons
Medulla
Cerebellum
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Gray and White Matter in CNS The basic pattern of the

Gray and White Matter in CNS

The basic pattern of the CNS

can be seen in the spinal cord
A central cavity surrounded by a gray matter core of brain nuclei, external to which is white matter (myelinated fiber tracts)
Figure 12.29 presents major ascending and descending fiber tracts
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Gray and White Matter in CNS The brain has the same

Gray and White Matter in CNS

The brain has the same basic

design except that it also contains additional regions of gray matter that are not evident in the spinal cord
Both the cerebral hemispheres and the cerebellum have an outer layer or cortex of gray matter consisting of neuron cell bodies
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Gray and White Matter in CNS The pattern of white and

Gray and White Matter in CNS

The pattern of white and gray

matter changes with descent through the brain stem
The cortex disappears, but scattered gray matter nuclei are seen within the white matter
At the caudal end of the brain stem the basic pattern is evident
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Ventricles of the Brain The ventricles of the brain arise from

Ventricles of the Brain

The ventricles of the brain arise from the

expansion of the neural tube
They are continuous with each other and with the central canal of the spinal cord
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Ventricles of the Brain The hollow ventricular chambers are filled with

Ventricles of the Brain

The hollow ventricular chambers are filled with cerebrospinal

fluid and lined by ependymal cells
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Ventricles of the Brain The paired lateral ventricles are large C-shaped

Ventricles of the Brain

The paired lateral ventricles are large C-shaped chambers

that reflect the pattern of cerebral growth
One lateral ventricle is located in each cerebral hemisphere
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Ventricles of the Brain Anteriorly, the lateral ventricles lie close together

Ventricles of the Brain

Anteriorly, the lateral ventricles lie close together separated

only by a thin median membrane called the septum pellucidum
Each ventricle communicates with the narrow third ventricle in the diencephalon
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Ventricles of the Brain Communication occurs through the inter- ventricular foramen (foramen of Moro)

Ventricles of the Brain

Communication occurs through the inter- ventricular foramen (foramen

of Moro)
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Ventricles of the Brain The third ventricle is continuous with the

Ventricles of the Brain

The third ventricle is continuous with the fourth

ventricle via the canal-like cerebral aqueduct that runs through the midbrain
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Ventricles of the Brain The fourth ventricle which lies dorsal to

Ventricles of the Brain

The fourth ventricle which lies dorsal to the

pons and posterior to the medulla, is continuous with the central canal of the spinal cord inferiorly

Pons

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Ventricles of the Brain Three openings mark the walls of the

Ventricles of the Brain

Three openings mark the walls of the fourth

ventricle
Paired lateral apertures
Median aperture
Apertures connect the ventricles to the subarachnoid space

Pons

Subarachnoid space is filled with
cerebrospinal fluid to surround the brain

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The Cerebral Hemispheres The cerebral hemispheres form the superior part of

The Cerebral Hemispheres

The cerebral hemispheres form the superior part of the

brain
These two structures account for about 83% of the mass of the brain
The two hemispheres cover and obscure the diencephalon and the top of the brain stem
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The Cerebral Hemispheres Nearly the entire surface of the cerebral hemispheres

The Cerebral Hemispheres

Nearly the entire surface of the cerebral hemispheres is

marked by elevated ridges of tissues called gyri separated by shallow grooves called sulci
Deeper grooves called fissures separate larger regions of the brain
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The Cerebral Hemispheres Prominent gyri and sulci are similar in all

The Cerebral Hemispheres

Prominent gyri and sulci are similar in all people
The

median longitudinal fissure separates the hemispheres
The transverse fissure separates the cerebral hemispheres from the cerebellum below
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Lobes of Cerebral Hemispheres Deeper sulci divide each hemisphere into five

Lobes of Cerebral Hemispheres

Deeper sulci divide each hemisphere into five lobes
Frontal

lobe
Temporal lobe
Parietal lobe
Occipital lobe
Insula (located within the lateral sulcus)

Insula

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Lobes of Cerebral Hemispheres Location of the insula deep within the

Lobes of Cerebral Hemispheres

Location of the insula deep within the Lateral

sulcus of the hemisphere

Insula

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Fissures of Cerebral Hemispheres Sulci divide lobes of the hemispheres Central

Fissures of Cerebral Hemispheres

Sulci divide lobes of the hemispheres
Central sulcus
Parieto-

occipital sulcus
Lateral sulcus
Transverse fissure
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Medial Surface of Right Hemisphere Medial surface of the right hemisphere showing the Parieto- occipital sulcus

Medial Surface of Right Hemisphere

Medial surface of the right hemisphere showing

the Parieto- occipital sulcus
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Position of Cerebral Hemispheres The frontal lobes occupy the anterior cranial

Position of Cerebral Hemispheres

The frontal lobes occupy the anterior cranial fossa
The

anterior parts of the temporal lobes fill the middle cranial fossa
The cerebellum and brain stem occupies the posterior cranial fossa and the occipital lobes rests upon it
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Cerebral Cortex The cerebral cortex is the “executive suite” of the

Cerebral Cortex

The cerebral cortex is the “executive suite” of the nervous

system
It enables us to perceive, communicate, remember, understand, appreciate, and initiate voluntary movements
Literally all qualities associated with conscious behavior or consciousness originate within the cerebral cortex of the various lobes of the brain
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Cerebral Cortex The cerebral cortex is gray matter composed of neuron

Cerebral Cortex

The cerebral cortex is gray matter composed of neuron cells

bodies, dendrites, and unmyelinated axons (plus support cells and blood vessels)
It is only 2-4 mm thick
The many convolutions of the brain effectively triple its surface area
It accounts for roughly 40% of total brain mass
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Cerebral Cortex The cerebral cortex accounts for roughly 40% of total

Cerebral Cortex

The cerebral cortex accounts for roughly 40% of total brain

mass
The cortex contains billions of neurons arranged in six layers
Ana
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Cerebral Hemispheres Coronal section of the brain which reveals the cerebral

Cerebral Hemispheres

Coronal section of the brain which reveals the cerebral cortex,

white matter, and basal nuclei within the cerebral hemispheres
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Cerebral Cortex Research on the structure and function of the brain

Cerebral Cortex

Research on the structure and function of the brain reveals

that there are both specialized and diffuse areas of function
Motor and sensory areas are localized in discrete cortical areas called domains
Many higher mental functions such as memory and language appear to have overlapping domains and are more diffusely located
Broadmann areas are areas of localized function
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Cerebral Cortex - Generalizations The cerebral cortex has three types of

Cerebral Cortex - Generalizations

The cerebral cortex has three types of functional

areas
Motor areas / control voluntary motor function
Sensory areas / provide conscious awareness of sensation
Association areas / act mainly to integrate diverse information for purposeful action
Each hemisphere is chiefly concerned with the sensory and motor functions of the opposite (contralateral) side of the body
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Cerebral Cortex - Generalizations Although they are largely symmetrical in structure

Cerebral Cortex - Generalizations

Although they are largely symmetrical in structure the

two hemispheres are not entirely equal in function, instead there is lateralization of cortical function
Remember that the information presented is a gross oversimplification to convey and clarify concepts
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Motor Areas Cortical areas controlling motor functions lie in the posterior

Motor Areas

Cortical areas controlling motor functions lie in the posterior part

of the frontal lobes
Motor areas include the primary motor cortex, the premotor cortex, Broca’s area, and the front eye field
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Primary Motor Cortex The primary motor cortex is located in the

Primary Motor Cortex

The primary motor cortex is located in the precentral

gyrus of the frontal lobe of each hemisphere
Large neurons (pyramidal cells) in these gyri allow us to consciously control the precise or skill voluntary movements of our skeletal muscles
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Pyramidal cells These long axons, which project to the spinal cord,

Pyramidal cells

These long axons, which project to the spinal cord, form

the massive voluntary motor tracts called the pyramidal, or corticospinal tracts
All other descending motor tracts issue from brain stem nuclei and consists of chains of two, three, or more neurons

Dendrites

Table 11.1

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Pyramidal Tracts The lateral corticospinal tract consists of the long axons

Pyramidal Tracts

The lateral corticospinal tract consists of the long axons of

the pyramidal cells located within the primary motor cortex
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Motor Somatotopy Body is represented spatially in the primary motor cortex

Motor Somatotopy

Body is represented spatially in the primary motor cortex

of each hemisphere
Most of the neurons in these gyri control muscles in body areas having the most precise motor control
The areas with the most control (face, tongue, and hands)
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Motor Somatotopy Motor innervation is contralateral; left primary motor controls right

Motor Somatotopy

Motor innervation is contralateral; left primary motor controls right

side of body
The image is useful to conceptualize areas of synergistic function
However, a given muscle may be controlled by several cortical neurons recruited for several specific actions
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Motor Somatotopy Damage to the localized areas of the primary motor

Motor Somatotopy

Damage to the localized areas of the primary motor

cortex paralyzes the muscles controlled by this area
If the lesion is in the right hemisphere, the left side will be paralyzed
Only voluntary control is lost as the muscles can still contract reflexively
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Premotor Cortex The premotor cortex controls motor skills of repetitive or

Premotor Cortex

The premotor cortex controls motor skills of repetitive or patterned

nature (typing or piano)
The premotor cortex coordinates the movement of several muscle groups to act simultaneously or sequentially
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Premotor Cortex The premotor cortex sends activating impulses to the primary

Premotor Cortex

The premotor cortex sends activating impulses to the primary motor

cortex
Also influences motor actively more directly by supplying about 15% of pyramidal tract fibers
A memory bank of skilled motor activities
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Premotor Cortex This area appears to involved with motor planning It

Premotor Cortex

This area appears to involved with motor planning
It controls voluntary

actions that depend on sensory feedback
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Premotor Cortex Damage to the premotor area results in the loss

Premotor Cortex

Damage to the premotor area results in the loss of

the motor skills in that region
Muscle strength and the ability to perform the discrete individual movements are not hindered
Neurons relearning the skill would require practice
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Broca’s area The area has long been considered to be present

Broca’s area

The area has long been considered to be present in

only one hemisphere (usually left)
A special motor speech area that directs the muscles of the tongue, throat, and lips in articulating words
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Broca’s area Recent PET scans indicates that Broca’s area and a

Broca’s area

Recent PET scans indicates that Broca’s area and a similar

area in the opposite hemisphere become active as we prepare to speak
The areas may be involved with planning speech and other voluntary motor activities
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Frontal Eye Field This cortical region controls the voluntary movements of

Frontal Eye Field

This cortical region controls the voluntary movements of the

eyes
Engaged when we look quickly at something, as in moving our eyes to follow a moving target
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Sensory Areas Areas concerned with the conscious awareness of sensation in

Sensory Areas

Areas concerned with the conscious awareness of sensation in the

parietal, temporal and occipital lobes
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Primary Somato-sensory Cortex Primary somato- sensory area resides in the postcentral

Primary Somato-sensory Cortex

Primary somato- sensory area resides in the postcentral

gyrus of the parietal lobe
Neurons in this gyrus receive information relayed via a three neuron synaptic chain from general sensory receptors in the skin and proprio- ceptors in muscles
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Synaptic Chain Central axons of sensory (1st order) neurons enter dorsal

Synaptic Chain

Central axons of sensory (1st order) neurons enter dorsal root

of spinal cord
Synapse with 2nd order neurons in medial lemniscal tract and ascend to Thalamus
Synapse with 3rd order neurons which transmit to somato- sensory cortex
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Primary Somato-sensory Cortex In the cortex neurons process the sensory information

Primary Somato-sensory Cortex

In the cortex neurons process the sensory information

and identify the precise area of the body being stimulated
This ability to localize (assign a location) a stimulus precisely is called spatial discrimination
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Motor and Sensory Somatotopy

Motor and Sensory Somatotopy

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Primary Somato-sensory Cortex The sensory spatial discrimination is contralateral with the

Primary Somato-sensory Cortex

The sensory spatial discrimination is contralateral with the right

hemisphere receiving inputs from the left side of the body
The entire body is represented spatially in the primary somatosensory area of each hemisphere
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Primary Somato-sensory Cortex The amount of sensory cortex devoted to a

Primary Somato-sensory Cortex

The amount of sensory cortex devoted to a particular

body region is related to how many sensory receptors are present
In humans the face (especially the lips) and fingertips are the most sensitive body areas
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Primary Somatosensory Cortex Damage to the primary somatisensory cortex destroys the

Primary Somatosensory Cortex

Damage to the primary somatisensory cortex destroys the conscious

ability to feel and localize touch, pressure, and vibrations on the skin
Most ability to feel pain and temperature is also lost, although these can still be felt in a vague, poorly localized way
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Somatosensory Association Area The area lies just posterior to the primary

Somatosensory Association Area

The area lies just posterior to the primary somata-

sensory cortex and has many connections with it (Broadmann 5,7)
The major function of the area is to integrate and analyze different somatic sensory inputs (touch, pressure, others) relayed to it by the primary somato- sensory cortex
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Somatosensory Association Area The somatosensory association area forms a comprehensive evaluation

Somatosensory Association Area

The somatosensory association area forms a comprehensive evaluation of

what is being felt relative to its size, texture and parts
The somatosensory association area draws upon stored memories of past sensory experiences to perceive the object as one you recognize
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Somatosensory Association Area Past associations allow you to recognize familiar objects

Somatosensory Association Area

Past associations allow you to recognize familiar objects (coins,

keys) without having to look at them
Someone with damage to this area would not be able to recognize what they are feeling without actually looking at the object
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Primary Visual Cortex The primary visual cortex (17) is located on

Primary Visual Cortex

The primary visual cortex (17) is located on the

posterior and medial portions of the occipital lobe
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Primary Visual Cortex Most of the primary visual cortex is located

Primary Visual Cortex

Most of the primary visual cortex is located on

the medial aspect of the occipital lobe buried within the deep calcarine sulcus
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Primary Visual Cortex The largest of all cortical sensory areas, the

Primary Visual Cortex

The largest of all cortical sensory areas, the primary

visual cortex receives visual information that originates on the retinas of the eyes
There is a map of visual space on the primary visual cortex analogous to the body map of the somato- sensory cortex
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Primary Visual Cortex Again, the right half of visual space is

Primary Visual Cortex

Again, the right half of visual space is represented

on the left visual cortex, the left half on the right cortex
If this cortical area is damaged, the person has no conscious awareness of what is being viewed and is functionally blind
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Primary Visual Cortex The primary visual cortex is the first of

Primary Visual Cortex

The primary visual cortex is the first of a

series of cortical areas that process visual input
The processing here is at a comparatively low level - noting the orientation of objects being viewed and putting the inputs from the two eyes together
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Visual Association Area This area surrounds the primary visual area and

Visual Association Area

This area surrounds the primary visual area and encompasses

much of the occipital lobe (18, 19)
Communicating with the primary visual area, the visual association area continues the processing of visual information
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Visual Association Area This area analyzes color, form and movement in

Visual Association Area

This area analyzes color, form and movement in light

of past visual experiences so that we might recognize & appreciate what we are seeing
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Visual Association Area Recent neuroimaging has revealed that complex visual processing

Visual Association Area

Recent neuroimaging has revealed that complex visual processing far

forward from the occipital lobe into the temporal and parietal lobes
Overall, about 30 cortical areas for visual processing have been identified, with each more sophisticated than the last
The visual information proceeds anteriorly through these visual areas in two streams
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Visual Association Area The ventral stream extends through the inferior part

Visual Association Area

The ventral stream extends through the inferior part of

the entire temporal lobe and is responsible for recognizing objects, words during reading, and faces
Facial recognition is right hemisphere only
The “what”
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Visual Association Area The dorsal stream extends through the posterior parietal

Visual Association Area

The dorsal stream extends through the posterior parietal cortex

to the postcentral gyrus and perceives spatial relationships among different objects
The “where” things are in space
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Visual Association Area The dorsal stream in the parietal lobe is

Visual Association Area

The dorsal stream in the parietal lobe is important

for spatial perception
The superior part of the lobe calculates how we move our limbs through space then sends this information to the motor cortex which dictates these movements
In addition, the parietal lobe is important for abstract mathematical abilities, which are highly visual, spatial in nature
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Visual Areas Damage to the visual cortex results in functional blindness

Visual Areas

Damage to the visual cortex results in functional blindness
Damage to

the visual association areas results in an ability to see but not comprehend what is seen
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Primary Auditory Cortex The primary auditory cortex is located on the

Primary Auditory Cortex

The primary auditory cortex is located on the superior

margin of the temporal lobe, primarily inside the lateral sulcus
Broadmann 41,42
It provides us with our conscious awareness of sound
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Primary Auditory Cortex Hearing receptors in the cochlear of the inner

Primary Auditory Cortex

Hearing receptors in the cochlear of the inner ear

transmit impulses to primary auditory cortex
Impulses related to loudness, rhythm, and especially pitch (high to low notes) is complied
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Auditory Association Area The auditory association area lies just posterior to

Auditory Association Area

The auditory association area lies just posterior to the

primary auditory area Broadmann 22
This area evaluates and classifies sound
Memories of past sounds seem to be stored here
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Auditory Association Area In one hemisphere (usually the left), the auditory

Auditory Association Area

In one hemisphere (usually the left), the auditory association

areas lies in the center of Wernicke’s area
This functional area is involved in recognizing and understanding spoken words
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Auditory Association Area Damage to Wernicke’s area interferes with the ability to comprehend speech

Auditory Association Area

Damage to Wernicke’s area interferes with the ability to

comprehend speech
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Gustatory (taste) Cortex The gustatory cortex is involved in the conscious

Gustatory (taste) Cortex

The gustatory cortex is involved in the conscious awareness

of tase stimuli
Broadmann 43
It lies on the roof of the lateral sulcus
This taste area occurs on the tongue in the somatosensory homunculus
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Vestibular (equilibrium) Cortex The cortex is responsible for conscious aware-ness of

Vestibular (equilibrium) Cortex

The cortex is responsible for conscious aware-ness of the

sense of balance; specifically the position of the head in space
Recent studies have placed this region in the posterior insula deep in the lateral sulcus
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Olfactory Area The primary olfactory cortex lie on the medial aspects

Olfactory Area

The primary olfactory cortex lie on the medial aspects of

the cerebrum in a small region called the piriform lobe of which the hook-like uncus is the dominant feature
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Olfactory Area The olfactory nerves (Cranial nerve I) from the nasal

Olfactory Area

The olfactory nerves (Cranial nerve I) from the nasal cavity

transmit impulses that are ultimately relayed to the olfactory cortex
The outcome is conscious awareness of smells
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Olfactory Area The olfactory cortex is part of a brain area

Olfactory Area

The olfactory cortex is part of a brain area called

the rhinencephalon (nose brain) which includes all parts of the cerebrum that directly receive olfactory signals
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Olfactory Area The piriform lobe, the olfactory tract, the olfactory bulb,

Olfactory Area

The piriform lobe, the olfactory tract, the olfactory bulb, and

some nearby structures are all components of the rhinencephalon
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Olfactory Area The rhinencephalon connects to the brain area that is

Olfactory Area

The rhinencephalon connects to the brain area that is involved

in emotions, the limbic system, which explains why smells often trigger emotions
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Olfactory Area Part of the frontal lobe, the orbitofrontal cortex, is

Olfactory Area

Part of the frontal lobe, the orbitofrontal cortex, is involved

in higher-order processing of smells
Consciously identifying and recalling specific odors and telling different smells apart
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Association Areas Association areas include all cortical areas other than primary

Association Areas

Association areas include all cortical areas other than primary sensory

and motor areas
The name reflects the fact that some of these areas tie together, or make associations between different kinds of sensory information
They also seem to associate new sensory inputs with memories of past experiences
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Association Areas The term association area is fading from use and

Association Areas

The term association area is fading from use and will

probably be replaced by higher- order processing areas
Higher-order processing areas is a more accurate name as these areas, which are nearby the primary sensory areas, have the ability to analyze, recognize, and act on the sensory input received
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Prefrontal Cortex The prefrontal cortex occupies the large region of the

Prefrontal Cortex

The prefrontal cortex occupies the large region of the frontal

lobe anterior to the motor area
The most complicated cortical region
It performs many cognitive functions
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Prefrontal Cortex Cognition is all aspects of thinking, perceiving and of

Prefrontal Cortex

Cognition is all aspects of thinking, perceiving and of intentionally

remembering and recalling information
The prefrontal cortex is necessary for abstract ideas, reasoning and judgment, impulse control, persistence, long term planning
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Prefrontal Cortex The prefrontal cortex also is used for long- term

Prefrontal Cortex

The prefrontal cortex also is used for long- term planning,

complex problem solving, mental flexibility, social skills, appreciating humor, empathy, and conscience
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Prefrontal Cortex The prefrontal cortex also seems to be related to

Prefrontal Cortex

The prefrontal cortex also seems to be related to mood

and has close links to the emotional (limbic) part of the forebrain
Tumors in this region may cause mental and personality disorders
The tremendous elaboration of this prefrontal region distinguishes humans from animals
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Prefrontal Cortex Functional neuro-imaging techniques have begun to reveal the functions

Prefrontal Cortex

Functional neuro-imaging techniques have begun to reveal the functions of

specific parts of the prefrontal cortex
Completion of multi-step problem solving tasks requires the temporary storage of information in working memory
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Prefrontal Cortex The working memories of spatial relations are stored in

Prefrontal Cortex

The working memories of spatial relations are stored in the

dorsolateral prefrontal cortex just anterior to the frontal eye field
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Prefrontal Cortex Working memories of objects and faces are stored farther ventrally, below Broca’s area

Prefrontal Cortex

Working memories of objects and faces are stored farther ventrally,

below Broca’s area
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Prefrontal Cortex More significant is the region that manages cognitive tasks

Prefrontal Cortex

More significant is the region that manages cognitive tasks by

directing our attention to the relevant information in the working memory
This executive area lies between the working- memory sites, just anterior to Broca’s area
Слайд 111

Prefrontal Cortex The extreme anterior pole of the frontal cortex was

Prefrontal Cortex

The extreme anterior pole of the frontal cortex was found

to be active in solving the most complex problems - problems in which many sub- problems had to be completed before a solution could be obtained
Слайд 112

Prefrontal Cortex The new findings suggest support for a general rule

Prefrontal Cortex

The new findings suggest support for a general rule of

neuroscience that says the farther rostrally one goes in the CNS, the more complex are the neuron functions performed
Слайд 113

Prefrontal Cortex The area just anterior to the corpus callosum may

Prefrontal Cortex

The area just anterior to the corpus callosum may process

emotions involved in “mentalization”, the ability to understand and manipulate other people’s thoughts and emotions
Слайд 114

General Interpretation Area The existence of this area within the brain

General Interpretation Area

The existence of this area within the brain is

debated
Once thought to be an area of integration of all types of sensory information, its existence was mainly substantiated by agnosia (not knowing)
Recent studies do not support its presence
Слайд 115

Language Area The large area surrounding the lateral sulcus in the

Language Area

The large area surrounding the lateral sulcus in the left

cerebral hemisphere is involved in various functions related to language
Слайд 116

Language Area Five areas have been identified with language; Broca’s area

Language Area

Five areas have been identified with language; Broca’s area (speech

production); Wernicke’s area (speech comprehension); prefrontal cortex (conceptual analysis); temporal lobe (visual and auditory aspects of language ); the insula (recognition of rhythms)
Слайд 117

Language Area The corresponding areas on the right hemisphere, although not

Language Area

The corresponding areas on the right hemisphere, although not involved

in the mechanics of language, act in the creative interpretation of words and in controlling the emotional overtones of speech
Слайд 118

Insula The insula is large and the functions of its cortex

Insula

The insula is large and the functions of its cortex are

not well understood
Some parts function in language and some in the sense of balance
Other parts have visceral function including the perception of upset stomach, full bladder
Слайд 119

Lateralization of Cortical Function We use both cerebral hemispheres for almost

Lateralization of Cortical Function

We use both cerebral hemispheres for almost every

task and it appears the hemispheres share memories and appear nearly identical
However, there are differences and unique abilities that are found in one hemisphere and not the other
This phenomenon is call lateralization
Cerebral dominance suggest that there is one hemisphere that dominates each task
Слайд 120

Lateralization of Cortical Function In most people (Approx. 90%) the left

Lateralization of Cortical Function

In most people (Approx. 90%) the left hemisphere

has greater control over language abilities, mathematical abilities, and logic
The other hemisphere (usually the right) is involved in visual-spatial skills, intuition, emotion, and appreciation of art and music
Слайд 121

Lateralization of Cortical Function Most individuals (90%) with left cerebral dominance

Lateralization of Cortical Function

Most individuals (90%) with left cerebral dominance are

right-handed
In the remaining 10% the roles of the hemispheres are reversed or the hemispheres share their functions equally
Typically, many right cerebral dominant people are left handed and more often male
In lefties the cerebral cortex functions bilaterally, the mutuality of brain control sometimes result in ambidexterity or dyslexia
Слайд 122

Lateralization of Cortical Function The two cerebral hemispheres have perfect and

Lateralization of Cortical Function

The two cerebral hemispheres have perfect and almost

instantaneous communication with one another via connecting fiber tracts as well as complete integration of their functions
Lateralization means that each hemisphere is better than the other at certain functions, neither side is better at everything
Слайд 123

Cerebral White Matter Communication within the brain is extensive The cerebral

Cerebral White Matter

Communication within the brain is extensive
The cerebral white matter

deep to the gray matter of the cortex provides for communication between cerebral areas and between the cortex and the lower CNS centers
Слайд 124

Cerebral White Matter The white matter largely consists of myelinated fibers

Cerebral White Matter

The white matter largely consists of myelinated fibers bundled

into large tracts
These fibers and the tracts they form are classified according to the direction in which they run as
Commissural
Association
Projection
Слайд 125

Cerebral White Matter Commissures connect the hemispheres Association fibers connect areas

Cerebral White Matter

Commissures connect the hemispheres
Association fibers connect areas within hemispheres
Projection

tracts connect higher & lower areas of CNS

Projection
Fibers

Commissure
Fibers

Слайд 126

Cerebral White Matter Commissures connect the corresponding areas of two hemispheres

Cerebral White Matter

Commissures connect the corresponding areas of two hemispheres enabling

them to function as a whole
The Corpus callosum is the largest commissure
Слайд 127

Cerebral White Matter Association fibers transmit within a single hemisphere Short

Cerebral White Matter

Association fibers transmit within a single hemisphere
Short fibers connect

adjacent gyri or cortical areas
Long fibers are bundled into tracts and connect different cortical lobes
Слайд 128

Cerebral White Matter Projection fibers run vertically to connect levels of

Cerebral White Matter

Projection fibers run vertically to connect levels of the

CNS
Impulses from receptors and to effectors move within these tracts
At the upper limits of the brain stem, the projection fibers on each side form a compact band called the internal capsule
Слайд 129

Cerebral White Matter Ascending projection tracts pass between the thalamus and

Cerebral White Matter

Ascending projection tracts pass between the thalamus and the

basal nuclei beyond which the radiate through the cerebral white matter to the cortex
This distinctive arrangement of projection tract fibers is called the corona radiata

Thalamus

Слайд 130

Cerebral White Matter The fibers of the corona radiata fan out

Cerebral White Matter

The fibers of the corona radiata fan out into

the white matter of the cerebral hemisphere
Слайд 131

Basal Nuclei In the cerebral white matter of each hemisphere are

Basal Nuclei

In the cerebral white matter of each hemisphere are a

groups of subcortical nuclei called the basal nuclei
The main mass of this tissue include the caudate nucleus, putamen, and the globus pallidus
Слайд 132

Basal Nuclei The putamen and globus pallidus together form a mass called the lentiform nucleus

Basal Nuclei

The putamen and globus pallidus together form a mass called

the lentiform nucleus
Слайд 133

Basal Nuclei The comma shaped caudate nucleus arches superiorly over the diencephalon

Basal Nuclei

The comma shaped caudate nucleus arches superiorly over the diencephalon

Слайд 134

Basal Nuclei The lentiform nucleus flanks the internal capsule laterally Lentiform nucleus

Basal Nuclei

The lentiform nucleus flanks the internal capsule laterally

Lentiform
nucleus

Слайд 135

Basal Nuclei Collectively the caudate nucleus and the lentiform nuclei are

Basal Nuclei

Collectively the caudate nucleus and the lentiform nuclei are called

the corpus striatum because the fibers of the internal capsule that course past these nuclei give them a striped appearance
Слайд 136

Basal Nuclei The basal nuclei are functionally associated with the subthalamic

Basal Nuclei

The basal nuclei are functionally associated with the subthalamic nuclei

(located in the floor of the diencephalon) and the substantia nigra of the midbrain
Слайд 137

Basal Nuclei The amygdaloid nucleus sits on the tail of the

Basal Nuclei

The amygdaloid nucleus sits on the tail of the caudate

nucleus, functionally it belongs to the limbic system
Слайд 138

Basal Nuclei Functionally, the basal nuclei can be viewed as complex

Basal Nuclei

Functionally, the basal nuclei can be viewed as complex neural

calculators that cooperate with the cerebral cortex in controlling movement
Слайд 139

Basal Nuclei The basal nuclei receive inputs from the entire cerebral

Basal Nuclei

The basal nuclei receive inputs from the entire cerebral cortex

as well as from other subcortical nuclei
Via relays through the thalamus, the basal nuclei project to the premotor and prefrontal cortices
Слайд 140

Basal Nuclei Via relays the basal nuclei influence muscle movements directed

Basal Nuclei

Via relays the basal nuclei influence muscle movements directed by

the primary motor cortex
The basal nuclei has no direct access to the motor pathways
The precise role of the basal nuclei is difficult to determine since their function overlaps to some extent with the cerebellum
The basal nuclei are particularly important in starting, stopping, and monitoring movements executed by the by the cortex
Слайд 141

Basal Nuclei The nuclei are involved in monitoring muscle movements that

Basal Nuclei

The nuclei are involved in monitoring muscle movements that are

relatively slow and sustained or patterned
The nuclei also regulated the intensity of these movements
Additionally, they inhibit antagonistic or unnecessary movements
When the basal nuclei are impaired, the result is disturbances in posture and muscle tone, involuntary movements including tremors, and abnormal slowness
Слайд 142

The Diencephanlon Forms the central core of the forebrain and is surrounded by the cerebral hemispheres

The Diencephanlon

Forms the central core of the forebrain and is surrounded

by the cerebral hemispheres
Слайд 143

The Diencephalon The diencephalon consists of three structures Thalamus Hypothalamus Epithalamus

The Diencephalon

The diencephalon consists of three structures
Thalamus
Hypothalamus
Epithalamus
These structures effectively enclose the

third ventricle

Hypothalamus

Thalamus

Epithalamus

Слайд 144

The Diencephalon The three structures of the diencephalon Thalamus Hypothalamus Epithalamus

The Diencephalon

The three structures of the diencephalon
Thalamus
Hypothalamus
Epithalamus
These structures are shown

with the hemispheres removed
Слайд 145

Thalamus The egg shaped thalamus makes up 80% of the diencephalon

Thalamus

The egg shaped thalamus makes up 80% of the diencephalon and

forms the superolateral walls of the third ventricle
Слайд 146

Thalamus The thalamus is composed of bilateral masses of gray matter

Thalamus

The thalamus is composed of bilateral masses of gray matter held

together by a mid- line commissure called the intermediate mass

Thalamus

Third
Ventricle

Intermediate
mass

Слайд 147

Thalamus The thalamus has many different nuclei, most named for their

Thalamus

The thalamus has many different nuclei, most named for their location
Each

of these nuclei has a functional specialization
Each projects fibers to and receives fibers from a specific region of the cerebral cortex
Слайд 148

The Thalamus Sensory inputs are not the only type of information

The Thalamus

Sensory inputs are not the only type of information relayed

through the thalamus
Every part of the brain that communicates with the cerebral cortex must relay signals through the nucleus of the thalamus
The thalamus can therefore be thought of as the gateway to the cerebral cortex
Слайд 149

Thalamus Afferent impulses from all senses and all parts of the

Thalamus

Afferent impulses from all senses and all parts of the body

converge on the thalamus and synapse with at least one of its nuclei
Within the thalamus, a sorting-out and information “editing” process occurs
Слайд 150

Thalamus Impulses having to do with similar functions are grouped together

Thalamus

Impulses having to do with similar functions are grouped together and

relayed via the internal capsule to the appropriate area of the sensory cortex as well as specific cortical association areas
Слайд 151

Thalamus In addition to sensory inputs, virtually all inputs ascending to

Thalamus

In addition to sensory inputs, virtually all inputs ascending to the

cerebral cortex funnel through thalamic nuclei
Ventral posterior lateral nucleus
General somatic sensory receptors (touch, pain pressure)
Слайд 152

Thalamus Lateral geniculate body Visual relay from retina Medial geniculate body

Thalamus

Lateral geniculate body
Visual relay from retina
Medial geniculate body
Auditory inputs
Anterior nuclear group
Regulation

of emotion and visceral function
Ventral lateral nuclei
Direct motor activity of cerebellum
Ventral anterior nuclei
Direct motor activity of basal nuclei
Слайд 153

Thalamus Pulvinar, medial dorsal and lateral nuclei are involved in the

Thalamus

Pulvinar, medial dorsal and lateral nuclei are involved in the integration

of sensory information and projection to specific association cortices
Слайд 154

Thalamus The thalamus plays a key role in mediating sensation, motor

Thalamus

The thalamus plays a key role in mediating sensation, motor activities,

cortical arousal, learning, and memory
It is truly the gateway to the cerebral cortex
Слайд 155

The Hypothalamus The hypothalamus is located below the thalamus, capping the brain stem Hypothalamus

The Hypothalamus

The hypothalamus is located below the thalamus, capping the brain

stem

Hypothalamus

Слайд 156

Hypothalamus Merging into the midbrain inferiorly, it extends from the optic

Hypothalamus

Merging into the midbrain inferiorly, it extends from the optic chiasma

to the posterior margin of the mammillary bodies

Mammillary
bodies

Optic
chiasma

Слайд 157

Mammillary Bodies The mammillary bodies are paired nuclei that bulge anteriorly

Mammillary Bodies

The mammillary bodies are paired nuclei that bulge anteriorly from

the hypothalamus that serve as relay stations in the olfactory pathways
Слайд 158

Hypothalamus Between the optic chiasma and the mammillary bodies is the

Hypothalamus

Between the optic chiasma and the mammillary bodies is the infundibulum
A

stalk of the hypothalamic tissue connects the pituitary gland to the base of hypothalamus
Слайд 159

Hypothalamus The hypothalamus contains about a dozen functionally important nuclei Despite

Hypothalamus

The hypothalamus contains about a dozen functionally important nuclei
Despite its small

size, the hypothalamus is the main visceral control center of the body and is vitally important to overall body homeostasis
Слайд 160

Autonomic Control Center The hypothalamus regulates involuntary nervous activity by controlling

Autonomic Control Center

The hypothalamus regulates involuntary nervous activity by controlling the

activity of autonomic centers in the brain stem and spinal cord
In this role the hypothalamus influences
Blood pressure
Rate and force of heart contraction
Motility of the digestive system
Respiratory rate and depth
Secretion of sweat and salivary glands
Слайд 161

Center for Emotional Response The hypothalamus has numerous connections with cortical

Center for Emotional Response

The hypothalamus has numerous connections with cortical association

areas, lower brain stem centers, and it lies at the center of the limbic system which is the emotional part of the brain
Nuclei involved in the perception of fear, pleasure, and rage, as well as those involved in the biological rhythms and drives of sex are found in the hypothalamus
Слайд 162

Center for Emotional Response The hypothalamus acts through the autonomic nervous

Center for Emotional Response

The hypothalamus acts through the autonomic nervous system

to initiate most physical expressions of emotion
Physical manifestations of fear
Pounding heart
Elevated blood pressure
Pallor
Sweating
Dry mouth
Слайд 163

Body Temperature Regulation The body’s thermostat is in the hypothalamus The

Body Temperature Regulation

The body’s thermostat is in the hypothalamus
The hypothalamus receives

input from the thermoreceptors located in other parts of the brain as well as in the body periphery
Homeostatic adjustments are then made to either cool or heat the body (sweating or shivering)
Hypothalamic centers also induce fever
Слайд 164

Body Temperature Regulation Hypothalamic receptors in the preoptic region monitor the

Body Temperature Regulation

Hypothalamic receptors in the preoptic region monitor the temperature

of the blood flowing through the hypothalamus
Слайд 165

Body Temperature Regulation According to signals received by the preoptic nuclei

Body Temperature Regulation

According to signals received by the preoptic nuclei the

hypothalamus initiates mechanisms to maintain relatively constant body temperature
Cooling / sweating
Heat generation / shivering
Слайд 166

Regulation of Hunger & Thirst In response to changing levels of

Regulation of Hunger & Thirst

In response to changing levels of glucose,

amino acids, hormones, and salts in the blood, the hypothalamus regulates feelings of hunger and satiety (ventro- medial nuclei)
Слайд 167

Regulation of Water Balance When body fluids become too concentrated, hypothalamic

Regulation of Water Balance

When body fluids become too concentrated, hypothalamic neurons

called osmoreceptors are activated
These receptors excite hypothalamic nuclei that trigger the release of antidiuretic hormone (ADH) from the posterior pituitary
ADH causes the kidneys to retain water
The same conditions also stimulate hypothalamic neurons in the thirst center, causing us to drink fluids
Слайд 168

Regulation of Sleep-Wake Cycles Acting with other brain regions, the hypothalamus

Regulation of Sleep-Wake Cycles

Acting with other brain regions, the hypothalamus helps

regulate the complex phenomenon of sleep
It is responsible for the timing of the sleep wake cycle
Слайд 169

Regulation of Sleep-Wake Cycles Hypothalamus through the operation of its suprachiasmatic

Regulation of Sleep-Wake Cycles

Hypothalamus through the operation of its suprachiasmatic nucleus

(our biological clock) sets the timing of the sleep-wake cycle in response to day-light darkness cues from visual pathways
Слайд 170

Control of Endocrine Functioning The hypothalamus acts as the helmsman of

Control of Endocrine Functioning

The hypothalamus acts as the helmsman of

the endocrine system
By producing releasing hormones, it controls the secretion of hormones by the anterior pituitary gland
The supraoptic and paraventricular nuclei produce hormones (ADH and oxytocin)
Слайд 171

Formation of Memory The nucleus of the mammillary body receives many

Formation of Memory

The nucleus of the mammillary body receives many inputs

from the major memory-processing structures of the cerebrum, the hippocampal formation and therefore may relate to memory formation
Слайд 172

Epithalamus The epithalamus is the posterior portion of the diencephalon It

Epithalamus

The epithalamus is the posterior portion of the diencephalon
It forms the

roof of the third ventricle

Epithalamus

Слайд 173

The Epithalamus The epithalmus consists of one tiny group of nuclei

The Epithalamus

The epithalmus consists of one tiny group of nuclei and

a small, unpaired knob called the pineal body
This gland, which derives from ependymal glial cells, is a hormone secreting organ
Слайд 174

Epithalamus The pineal gland extends from the posterior border of the

Epithalamus

The pineal gland extends from the posterior border of the epithalamus


The pineal gland secretes the hormone melatonin which signals the sleep- wake cycle

Pinal
Body

Слайд 175

The Epithalamus A cerebrospinal fluid-forming structure called a choroid plexus is

The Epithalamus

A cerebrospinal fluid-forming structure called a choroid plexus is also

part of the epithalamus

Choroid
Plexus

Слайд 176

The Brain Stem The third of the four major parts of

The Brain Stem

The third of the four major parts of the

brain is the brain stem
From superior to inferior, the brain stem is divided into;
Midbrain
Pons
Medulla oblongata

Midbrain

Pons

Medulla
oblongata

Слайд 177

The Brain Stem Each region is roughly an inch long Together

The Brain Stem

Each region is roughly an inch long
Together than constitute

2.5% of total brain mass
The brain stem has several functions
It produce the rigidly programmed, automatic behaviors necessary for our survival
Acts as a passageway for all the fiber tracts running between the cerebrum and spinal cord
It is heavily involved with the innervation of the face and head as 10 of the 12 cranial nerve attach to it
Слайд 178

The Brain Stem The brain stem has the same structural plan

The Brain Stem

The brain stem has the same structural plan as

the spinal cord, with outer white matter surrounding an inner region of gray matter
However, there are also nuclei of gray matter located within the white matter
Слайд 179

The Midbrain The midbrain is located between the diencephalon superiorly and the pons inferiorly

The Midbrain

The midbrain is located between the diencephalon superiorly and the

pons inferiorly
Слайд 180

The Midbrain Its central cavity is the cerebral aqueduct, which divides

The Midbrain

Its central cavity is the cerebral aqueduct, which divides it

into a tectum (dorsal surface) and paired cerebral peduncles
From an anterior view the cerebral peduncles appear as columns that hold up the cerebrum
Слайд 181

The Midbrain These peduncles contain the pyramidal (corticospinal) motor tracts descending

The Midbrain

These peduncles contain the pyramidal (corticospinal) motor tracts descending toward

the spinal cord
The ventral part of each peduncle contains the tract called the crus cerebri
Слайд 182

The Midbrain Dorsally, the midbrain has the superior cerebellar peduncles which connect midbrain to the cerebellum

The Midbrain

Dorsally, the midbrain has the superior cerebellar peduncles which connect

midbrain to the cerebellum
Слайд 183

The Midbrain Surrounding the cerebral aqueduct is the peri-aqueductal gray matter

The Midbrain

Surrounding the cerebral aqueduct is the peri-aqueductal gray matter that

has two somewhat related functions
Слайд 184

The Midbrain The periaqueductal gray matter is involved in the “fright-and-flight”

The Midbrain

The periaqueductal gray matter is involved in the “fright-and-flight” sympathetic

reaction
The gray matter is a link between the amygdala of the forebrain (which perceives fear) and the autonomic pathway (which directly signals the physiological reactions associated with fear)
Слайд 185

The Midbrain The gray matter elicits A terror-induced increase in heart

The Midbrain

The gray matter elicits
A terror-induced increase in heart rate
Skyrocketing

blood pressure
Wild fleeing or defensive freezing
The flexing of the spine as in curling into a ball for protection
The suppression of pain upon injury
Слайд 186

The Midbrain The periaqueductal gray matter also seems to mediate our

The Midbrain

The periaqueductal gray matter also seems to mediate our response

to visceral pain (as when nauseous) during which it
Decreases heart rate and blood pressure
Produce a cold sweat
Discourages movement
Слайд 187

The Midbrain The most ventral part of the para- aqueductal gray

The Midbrain

The most ventral part of the para- aqueductal gray mattercontains

cell bodies of motor neurons that contribute to two cranial nerves
Oculomotor (III)
Trochlear (IV)
These cranial nerves control most muscles that move the eyes
Слайд 188

The Midbrain Nuclei are also scattered in the surrounding white matter

The Midbrain

Nuclei are also scattered in the surrounding white matter
The largest

of these nuclei are the corpora quadrigemia which raise four dome like protrusions on the dorsal midbrain surface

Corpora
quadrigemia

Слайд 189

The Midbrain The superior pair of nuclei, the superior colliculus are

The Midbrain

The superior pair of nuclei, the superior colliculus are visual

reflex centers that
coordinate head and eye movements when following a moving object
Make us turn our head involuntarily when we detect movement in our peripherial vision

Superior
colliculus

Слайд 190

The Midbrain The inferior colliculus are part of the auditory relay

The Midbrain

The inferior colliculus are part of the auditory relay from

the hearing receptors of the ear to the sensory cortex
Act in reflexive response to sound as in the startle reflex
Turn your head toward unexpected source of sound

Inferior
Colliculus

Слайд 191

The Midbrain Also imbedded in the white matter of the midbrain

The Midbrain

Also imbedded in the white matter of the midbrain are

two pigmented nuclei, the substantia nigra and the red nucleus
Слайд 192

The Midbrain The substantia nigra is a bandlike nucleus located deep

The Midbrain

The substantia nigra is a bandlike nucleus located deep to

the cerebral peduncle
It is the largest nuclear mass in the midbrain
Слайд 193

The Midbrain Its dark color reflects its high content of melanin

The Midbrain

Its dark color reflects its high content of melanin pigment,

a precursor of dopamine a neurotransmitter released by these neurons
The substantia nigra is functionally linked to the basal nuclei of the cerebral hemispheres
Слайд 194

The Midbrain The red nucleus is found between the substantia nigra

The Midbrain

The red nucleus is found between the substantia nigra and

the cerebral aqueduct
It reddish hue is due to its vascular supply and the presence of iron pigment in the cell bodies of its neurons
Слайд 195

The Midbrain The red nuclei are relay nuclei in some descending

The Midbrain

The red nuclei are relay nuclei in some descending motor

pathways that effect limb flexion
The red nuclei is the largest nucleus in the reticular formation, a system of small nuclei scattered through the core of the brain stem
Слайд 196

The Pons The pons is the bulging brain stem region wedged

The Pons

The pons is the bulging brain stem region wedged between

the midbrain and the medulla oblongata

Pons

Слайд 197

The Pons It forms part of the anterior wall of the

The Pons

It forms part of the anterior wall of the fourth

ventricle
It is chiefly composed of conduction tracts
The deep projection fibers run longitudinally and complete the pathway between higher brain centers and spinal cord

Pons

Слайд 198

The Pons The deep projection fibers run longitudinally and complete the

The Pons

The deep projection fibers run longitudinally and complete the superior-inferior

pathway between the higher brain centers and the spinal cord

Pons

Слайд 199

The Pons The more superficial nuclei are relays for conversations between

The Pons

The more superficial nuclei are relays for conversations between the

motor cortex and the cerebellum
These fibers are orientated dorsally and transversely and connect the pons bilaterally with the cerebellum

Middle
Cerebellar
peduncles

Слайд 200

The Pons Several cranial nerves issue from pons nuclei Trigeminal nerve Abducens nerve Facial nerves

The Pons

Several cranial nerves issue from pons nuclei
Trigeminal nerve
Abducens nerve
Facial

nerves
Слайд 201

The Pons Other important pons nuclei are part of the reticular

The Pons

Other important pons nuclei are part of the reticular formation
The

pneumotaxic center is a respiratory center
Functioning with medullary respiratory centers it helps to maintain the normal rhythm of breathing
Слайд 202

The Medulla Oblongata The medulla oblongata is the most inferior part

The Medulla Oblongata

The medulla oblongata is the most inferior part of

the brain stem

Medulla
oblongata

Слайд 203

The Medulla Oblongata The medulla blends into the spinal cord at

The Medulla Oblongata

The medulla blends into the spinal cord at the

level of the foramen magnum
The central canal of the spinal cord continues upward into the medulla where it broaden to form the fourth ventricle
Слайд 204

The Medulla Oblongata The medulla has several externally visible landmarks which

The Medulla Oblongata

The medulla has several externally visible landmarks which form

longitudinal ridges on the ventral surface called the pyramids
These are formed by the large pyramidal tracts descending from the motor cortex

Pyramids

Слайд 205

The Medulla Oblongata Just above the medulla-spinal cord junction most of

The Medulla Oblongata

Just above the medulla-spinal cord junction most of the

fibers cross over to the opposite side before continuing their descent into the spinal cord
The crossover point is called the decussation of the pyramids

Decussation
Of pyramids

Слайд 206

The Medulla Oblongata The consequence of this crossover is that each

The Medulla Oblongata

The consequence of this crossover is that each hemisphere

chiefly controls the voluntary movements of muscles on the opposite or contralateral side of the body

Decussation
Of pyramids

Слайд 207

The Medulla Oblongata The inferior cerebellar peduncles are fiber tracts that

The Medulla Oblongata

The inferior cerebellar peduncles are fiber tracts that connect

the medulla to the cerebellum dorsally
The olives are oval swellings produced by the underlying inferior olivary nuclei
Слайд 208

The Medulla Oblongata The olivary nuclei relay sensory information on the

The Medulla Oblongata

The olivary nuclei relay sensory information on the state

of stretch of our muscles and joints to the cerebellum
Слайд 209

The Medulla Oblongata The rootlets of the hypoglossal nerves emerge from

The Medulla Oblongata

The rootlets of the hypoglossal nerves emerge from the

groove between the pyramid and olive on each side of the brain stem
Слайд 210

The Medulla Oblongata Other cranial nerves associated with the medulla are

The Medulla Oblongata

Other cranial nerves associated with the medulla are the

Glossopharyngeal, Vagus, and portions of the Accessary nerves
Слайд 211

The Medulla Oblongata The fibers of the vestibulocochlear synapse with the

The Medulla Oblongata

The fibers of the vestibulocochlear synapse with the cochlear

nuclei which receive information on auditory inputs
Слайд 212

The Medulla Oblongata Also housed within the medulla are several nuclei

The Medulla Oblongata

Also housed within the medulla are several nuclei associated

with ascending sensory tracts
The most dominant of these are the dorsally located nucleus gracilis and nucleus cuneatus associated with the medial lemniscal tract
Слайд 213

Medulla Oblongata These serve as relay nuclei in a pathway by

Medulla Oblongata

These serve as relay nuclei in a pathway by which

general somatic sensory information ascends from the spinal cord to the somatosensory cortex
Слайд 214

The Medulla Oblongata The medulla has a critical role as an

The Medulla Oblongata

The medulla has a critical role as an autonomic

reflex center involved in maintaining body homeostasis
The cardiovascular center
The respiratory centers
Other centers
Слайд 215

The Medulla Oblongata The cardiac center The cardiac center adjusts the

The Medulla Oblongata

The cardiac center
The cardiac center adjusts the force and

rate of heart contraction to meet bodily needs
Слайд 216

The Medulla Oblongata The vasomotor center The vasomotor center regulates blood

The Medulla Oblongata

The vasomotor center
The vasomotor center regulates blood pressure by

acting on smooth muscle in the walls of the blood vessels to effect changes in blood vessel diameter
Vasoconstriction causes blood pressure to rise; dilation reduces blood pressure
Слайд 217

The Medulla Oblongata The respiratory centers The medullary respiratory centers control

The Medulla Oblongata

The respiratory centers
The medullary respiratory centers control the rate

and depth of breathing and maintains respiratory rhythm
Слайд 218

The Medulla Oblongata Other centers Additional centers regulate activities such as Vomiting Hiccuping Swallowing Coughing Sneezing

The Medulla Oblongata

Other centers
Additional centers regulate activities such as
Vomiting
Hiccuping
Swallowing
Coughing
Sneezing

Слайд 219

The Medulla Oblongata Many functions of the medulla overlap with those

The Medulla Oblongata

Many functions of the medulla overlap with those attributed

to the hypothalamus
The overlap is easily explained
The hypothalamus exerts its control over most visceral functions by relaying its instructions through the medulla’s reticular centers (within the Medulla oblongata) which carry them out
Слайд 220

The Cerebellum The cerebellum is exceeded in size only by the

The Cerebellum

The cerebellum is exceeded in size only by the cerebrum
It

accounts for about 11% of total brain mass
Слайд 221

The Cerebellum The cerebellum is located dorsal to the pons and

The Cerebellum

The cerebellum is located dorsal to the pons and medulla

under the occipital lobe of the cerebral hemispheres

Cerebellum

Слайд 222

The Cerebellum It is separated from the occipital lobe by the

The Cerebellum

It is separated from the occipital lobe by the transverse

fissure
It rests in the posterior cranial fossa of the skull
Слайд 223

The Cerebellum The cerebellum processes inputs received from Cerebral motor cortex

The Cerebellum

The cerebellum processes inputs received from
Cerebral motor cortex
Various brain

stem nuclei
Sensory receptors
The cerebellum provides precise timing and appropriate patterns of skeletal muscle contraction
Need for the smooth, coordinated movements of daily living
Cerebeller activity occurs subconsciously; we have no awareness of its functioning
Слайд 224

The Cerebellum The cerebellum is bilaterally symmetrical Its two cerebellar hemispheres

The Cerebellum

The cerebellum is bilaterally symmetrical
Its two cerebellar hemispheres are connected

medially by the wormlike vermis

Vermis

Слайд 225

The Cerebellum Its surface is heavily convoluted Fissure are all transversely

The Cerebellum

Its surface is heavily convoluted
Fissure are all transversely orientated
The surface

exhibits fine, parallel, pleatlike gyri known as folia

Vermis

Слайд 226

The Cerebellum Deep fissures divide each hemisphere into three lobes Anterior

The Cerebellum

Deep fissures divide each hemisphere into three lobes
Anterior lobe
Posterior lobe
Flocculonodular

lobe* (Cannot be seen in a surface view)

Anterior

Posterior

Слайд 227

The Cerebellum The cerebellum has a thin outer cortex of gray

The Cerebellum

The cerebellum has a thin outer cortex of gray matter
Internal

white matter
Small, deeply situated paired masses of gray matter
Слайд 228

The Cerebellum Several types of neurons are found in the cerebellur

The Cerebellum

Several types of neurons are found in the cerebellur cortex
Stellate
Basket
Granule
Purkinje

Purkinje

Granule

Basket

&
Stellate
Слайд 229

The Cerebellum The large Purkinje cells with their extensively branched dendrites

The Cerebellum

The large Purkinje cells with their extensively branched dendrites are

the only cortical neurons that send their axons through the white matter to synapse with the central nuclei of the cerebellum
These nuclei mediate most of the output of the cerebellum
Слайд 230

The Cerebellum The anterior and posterior lobes of the cerebellum act

The Cerebellum

The anterior and posterior lobes of the cerebellum act to

coordinate body movements
The lobes have completely overlapping sensory and motor maps of the entire body
Слайд 231

The Cerebellum The medial portions receive information from the axial portion

The Cerebellum

The medial portions receive information from the axial portion of

the body and influence the motor activities of the trunk and girdle muscles by relaying information to the cerebral motor cortex
Слайд 232

The Cerebellum The intermediate parts of each hemisphere are more concerned

The Cerebellum

The intermediate parts of each hemisphere are more concerned with

the distal parts of the limbs and skilled movements
Слайд 233

The Cerebellum The lateral parts of each hemisphere receive inputs from

The Cerebellum

The lateral parts of each hemisphere receive inputs from the

association areas of the cerebral cortex and appear to play a role in planning rather than executing movements
Слайд 234

The Cerebellum The small flocculonodular lobes receive inputs from the equilibrium

The Cerebellum

The small flocculonodular lobes receive inputs from the equilibrium apparatus

of the inner ears, are concerned with maintaining balance and controlling certain eye movements
Слайд 235

The Cerebellum Three pairs of fiber tracts, cerebellur peduncles connect the

The Cerebellum

Three pairs of fiber tracts, cerebellur peduncles connect the the

cerebellum to the brain stem
Слайд 236

The Cerebellum Virtually all fibers entering and leaving the cerebellum are

The Cerebellum

Virtually all fibers entering and leaving the cerebellum are ipsilateral;

from and to the same side of the body
Слайд 237

The Cerebellum The superior cerebellar peduncles connect the cerebellum and the

The Cerebellum

The superior cerebellar peduncles connect the cerebellum and the midbrain.

Fibers in these peduncles originate in the deep cerebellar nuclei and communicate with the cerebral motor cortex via thalamic relays
Слайд 238

The Cerebellum The middle cerebellar peduncles connect the pons the cerebellum.

The Cerebellum

The middle cerebellar peduncles connect the pons the cerebellum.

Слайд 239

The Cerebellum These fibers allow one-way communication from the pons to

The Cerebellum

These fibers allow one-way communication from the pons to the

cerebellar neurons, which enables the cerebellum to be advised of coluntary motor activities initiated by the motor cortex
Слайд 240

The Cerebellum The inferior cerebellar peduncles connect the cerebellum and the medulla

The Cerebellum

The inferior cerebellar peduncles connect the cerebellum and the medulla

Слайд 241

The Cerebellum These peduncles contain afferent tracts conveying sensory information to

The Cerebellum

These peduncles contain afferent tracts conveying sensory information to the

cerebellum from (1) muscle proprioceptors throughout the body and (2) vestibular nuclei of the brain stem concerned with balance & equil.
Слайд 242

Cerebellar Processing - 1 The frontal motor association areas of the

Cerebellar Processing - 1

The frontal motor association areas of the cerebral

cortex indicates its intents to initiate voluntary muscle contractions
Through collateral fibers of the pyramdial tracts, it notifies the cerebellum of its activity
Слайд 243

Cerebellar Processing - 2 At the same time, the cerebellum receives

Cerebellar Processing - 2

At the same time, the cerebellum receives information

from the proprioceptors throughout the body
Tension in muscles, tendons, and joint positions
From visual and equilibrium pathways
This information enables the cerebellum to determine where the body is and where it is going
More specifically where the parts of the body are located in space and how are they moving
Слайд 244

Cerebellar Processing - 3 The cerebellar cortex assesses this information and

Cerebellar Processing - 3

The cerebellar cortex assesses this information and calculates

the best way to coordinate the force, direction, and extent of muscle contraction
Prevents overshoot
Maintains posture
Ensures smooth, coordinated movements
Слайд 245

Cerebellar Processing - 4 Via the superior peduncles, the cerebellum dispatches

Cerebellar Processing - 4

Via the superior peduncles, the cerebellum dispatches its

“blueprint” for coordination to the cerebral motor cortex which makes appropriate adjustments in its motor plan
Cerebellar fibers also flow to brain stem nuclei, such as the red nuclei of the midbrain, which in turn project to motor neurons of the spinal cord
Слайд 246

The Cerebellum The cerebellum continually compares the higher brain’s intention with

The Cerebellum

The cerebellum continually compares the higher brain’s intention with the

body’s performance and sends out messages to initiate the appropriate measures
In this way, it helps to promote smooth voluntary movements that are precise and economical in terms of muscular effort
Слайд 247

The Cerebellum Cerebellar injury results in the loss of muscle tone

The Cerebellum

Cerebellar injury results in the loss of muscle tone and

clumsy, unsure movements, and sometimes even impaired thoughts about movements
Слайд 248

Functional Brain Systems Functional brain systems are networks of neurons that

Functional Brain Systems

Functional brain systems are networks of neurons that work

together but span relatively large distances with the brain
They are not localized to a specific region of the brain
The Limbic System (distributed within forebrain)
The Reticular Formation (distributed within the brainstem)
Слайд 249

The Limbic System The limbic system is a group of structures

The Limbic System

The limbic system is a group of structures located

on the medial aspect of each cerebral hemisphere and diencephalon
Слайд 250

The Limbic System The limbic system encircles the upper part of

The Limbic System

The limbic system encircles the upper part of the

brain stem and includes
Septal nuclei, Cingulate gyrus, hippocampal formation, and part of the Amygdala,
In the diencephalon the limbic system structures are the hypothalamus and the anterior thalamic nuclei of the thalamus
The fornix and other fiber tracts link these limbic system regions together
Слайд 251

The Limbic System The observation that odors evoke emotional reactions and

The Limbic System

The observation that odors evoke emotional reactions and memories

reflects the fact that these structures are linked to the rhinencephalon
Слайд 252

The Limbic System The limbic system is our emotional or affective

The Limbic System

The limbic system is our emotional or affective brain
Two

parts seem especially important in emotions
The amygdala
The cingulate gyrus
Слайд 253

The Limbic System The amygdala contains the key nuclei for processing

The Limbic System

The amygdala contains the key nuclei for processing fear

and then stimulating the appropriate sympathetic response to fear
Слайд 254

The Limbic System The amygdala also enables us to recognize menacing

The Limbic System

The amygdala also enables us to recognize menacing facial

expression in others and to detect the precise direction of the gaze of someone who is looking at us
Слайд 255

The Limbic System The cingulate gyrus allows us to shift between

The Limbic System

The cingulate gyrus allows us to shift between thoughts

and to express our emotions through gestures
Слайд 256

The Limbic System The anterior part of the gyrus interprets pain

The Limbic System

The anterior part of the gyrus interprets pain as

unpleasant and resolves mental conflict during frustrating tasks
Слайд 257

The Limbic System The limbic system also functions in consolidating and

The Limbic System

The limbic system also functions in consolidating and retrieving

memories
The structures involved, both of which are in the medial aspect of the temporal lobe, are the amygdala and the hippocampal formation
The hippocampal formation consists of the hippocampus and the parahippocampal gyrus
Слайд 258

The Limbic System The hippocampal formation encodes, consolidates, and later retrieves

The Limbic System

The hippocampal formation encodes, consolidates, and later retrieves memories

of facts and events
It first receives information to be remembered from the rest of the cerebral cortex; then it processes these data and returns then to the cortex, where they are stored as long-term memories
Слайд 259

The Limbic System The amygdala forms memories of experiences that are

The Limbic System

The amygdala forms memories of experiences that are based

entirely on their emotional impact, especially if related to fear
If we later are reminded of these experiences, the amygdala retreives the memories and causes us to re-experience the original emotion
The benefit is that it lets us make difficult and risky decisions correctly, based on memories of our past emotional experiences
Слайд 260

The Limbic System The limbic system communicates with many other regions

The Limbic System

The limbic system communicates with many other regions of

the brain
Most output from the limbic system is relayed through the hypothalamus and the reticular formation, the portions of our brain that control our visceral responses
Слайд 261

The Limbic system This fact explains why people under emotional stress

The Limbic system

This fact explains why people under emotional stress experience

visceral illnesses such as high blood pressure and heartburn
The limbic system also interacts heavily with the prefrontal lobes of the cerebral cortex
Thus, our feelings (mediated by the emotional brain) and our thoughts (mediated by the thinking brain) interact closely
Слайд 262

The Limbic System We react emotionally to things we consciously understand

The Limbic System

We react emotionally to things we consciously understand to

be happening
We are consciously aware of the emotional aspect of our lives
Слайд 263

The Limbic System Communication between the cerebral cortex and the limbic

The Limbic System

Communication between the cerebral cortex and the limbic system

explains why emotions sometimes override logic
It also explains why reason can stop us from expressing our emotions in inappropriate ways
Слайд 264

The Reticular Formation The reticular formation extends through the central core

The Reticular Formation

The reticular formation extends through the central core of

the medulla oblongata, pons, and midbrain
Слайд 265

The Reticular Formation It is an intricate system composed of loosely

The Reticular Formation

It is an intricate system composed of loosely clustered

neurons in what is otherwise white matter
Слайд 266

The Reticular Formation Reticular neurons can be localized into three broad

The Reticular Formation

Reticular neurons can be localized into three broad columns

along the length of the brain stem
Raphe
Medial nuclear (large cell) group
Lateral nuclear (small cell) group
Слайд 267

The Reticular Formation The outstanding feature of the reticular neurons is

The Reticular Formation

The outstanding feature of the reticular neurons is their

far-flung axonal connections
Individual reticular neurons project to the thalamus, cerebellum, and spinal cord
Widespread connections make reticular neurons ideal for governing the arousal of the brain as a whole
Слайд 268

The Reticular Formation Certain reticular neurons send a continuous stream of

The Reticular Formation

Certain reticular neurons send a continuous stream of impulses

to the cerebrum (through relays in the thalamus) thereby maintaining the cerebral cortex in an alert state
This arm of the reticular formation is called the reticular activating system or RAS
Слайд 269

The Reticular Activating System The RAS synapses with all major ascending

The Reticular Activating System

The RAS synapses with all major ascending sensory

tracts enhancing arousal of the cerebrum
The RAS functions in sleep and in arousal from sleep
It can be affected by general anesthesia, alcohol, tranquilizers, and sleep inducing drugs
Head trauma can also lead to loss of consciousness
Слайд 270

Reticular Formation The RAS also acts as a filter to dampen

Reticular Formation

The RAS also acts as a filter to dampen repetitive,

familiar, or weak signals
It is estimated that 99% of all sensory stimuli is disregarded as unimportant
Слайд 271

The Reticular Activating System The activity of the RAS is inhibited

The Reticular Activating System

The activity of the RAS is inhibited

by sleep centers in the hypothalamus and other neural regions
Damage to the RAS limits arousal and can result in coma
Слайд 272

The Reticular Formation The reticular formation also has a motor component

The Reticular Formation

The reticular formation also has a motor component
Some if

its motor nuclei project to motor neurons in the spinal cord via the reticulospinal tracts
These help control the skeletal muscles during coarse movements of the limbs
Other reticular motor nuclei are autonomic centers that regular visceral motor functions (heart rate & respiration)
Слайд 273

Protection of the Brain Nervous tissue is soft and vulnerable The

Protection of the Brain

Nervous tissue is soft and vulnerable
The brain is

protected by
Bony enclosure / skull
Menbranes / meninges
Watery cushion / cerebrospinal fluid
Collectively these tissues protect the brain from trauma and pressure
Furthermore, the brain is protected from harmful substances in the blood by the blood-brain barrier
Слайд 274

Meninges The meninges are three connective tissue membranes that lie just

Meninges

The meninges are three connective tissue membranes that lie just external

to the central nervous system organs
Слайд 275

Meninges The meningeal membranes Cover and protect the CNS organs Protect

Meninges

The meningeal membranes
Cover and protect the CNS organs
Protect blood vessels

and enclose venous sinuses
Contain cerebrospinal fluid
Form partitions within the skull
Слайд 276

Meninges The meninges are three connective tissue membranes that lie just

Meninges

The meninges are three connective tissue membranes that lie just external

to the central nervous system organs
Слайд 277

Meninges From external to internal, the meningeal layers are Dura mater Arachnoid Pia mater

Meninges

From external to internal, the meningeal layers are
Dura mater
Arachnoid
Pia mater

Слайд 278

The Dura Mater The leathery dura mater is by far the

The Dura Mater

The leathery dura mater is by far the strongest

of the meninges
Where it surrounds the brain it is a double layer membrane
Слайд 279

The Dura Mater The periosteal layer is the superficial and lines

The Dura Mater

The periosteal layer is the superficial and lines the

inner surface of the skull
The deeper meningeal layer forms the true external covering of the brain and continues caudally in the vertebral canal as the dural sheath of the spinal cord
Слайд 280

The Dura Mater The brain’s dural layers are fused together except

The Dura Mater

The brain’s dural layers are fused together except in

certain areas where they enclose the dural sinuses
The dural sinuses collect venous blood and direct it into the internal jugular veins of the neck
Слайд 281

The Dura Mater In several places the meningeal dura mater extends

The Dura Mater

In several places the meningeal dura mater extends inward

to form flat septa that anchor the brain to the skill
Слайд 282

The Dura Mater The falx cerebri dips into the longitudinal fissue

The Dura Mater

The falx cerebri dips into the longitudinal fissue
It attaches

to the crista galli of the ethmoid bone
Слайд 283

The Dura Mater The falx cerebelli forms a midline partition that

The Dura Mater

The falx cerebelli forms a midline partition that runs

along the vermis of the cerebellum
Слайд 284

The Dura Mater The tentorium cerebelli extends into the transverse fissue

The Dura Mater

The tentorium cerebelli extends into the transverse fissue between

the cerebral hemispheres and the cerebellum
Слайд 285

The Arachnoid Mater The middle membrane forms a loose brain covering

The Arachnoid Mater

The middle membrane forms a loose brain covering over

the surface of the cerebrum
It is separated from the dura mater by a narrow serous cavity, the subdural space
Beneath the arachnoid membrane is the wide subarachnoid space
Слайд 286

The Arachnoid Mater The subarachnoid space is filled with cerebrospinal fluid

The Arachnoid Mater

The subarachnoid space is filled with cerebrospinal fluid and

contains the largest blood vessels serving the brain
Since the arachnoid is fine and elastic, these blood vessels are rather poorly protected
Слайд 287

The Arachnoid Mater Arachnoid villi protrude through the overlying dura mater

The Arachnoid Mater

Arachnoid villi protrude through the overlying dura mater and

into the dural sinuses overlying the superior aspect of the brain
Cerebrospinal fluid is absorbed into the venous blood sinuses through these valvelike villi
Слайд 288

The Pia Mater The pia mater is a delicate connective tissue

The Pia Mater

The pia mater is a delicate connective tissue that

is richly invested with tiny blood vessels
It is the only membrane that clings tightly to the brain, following its every convolution
Слайд 289

Cerebrospinal Fluid (CSF) CSF is found in and around the brain

Cerebrospinal Fluid (CSF)

CSF is found in and around the brain and

spinal cord
It forms a liquid cushion that gives bouyancy to the CNS organs
By floating the brain, the CPF reduces brain weight by 97% and thus prevents the brain from crushing under its own weight
CSF also protects the brain and spinal cord from trauma
CSF also helps to nourish the brain
Слайд 290

Cerebrospinal Fluid (CSF) CSF is a similar in composition to blood

Cerebrospinal Fluid (CSF)

CSF is a similar in composition to blood plasma,

from which it arises
It contains less protein and more vitamin C and its ion concentration is different
CSF composition is important in the control of cerebral blood flow
Слайд 291

Choroid Plexus Choroid plexus hang from the roof of each ventricle

Choroid Plexus

Choroid plexus hang from the roof of each ventricle
These plexuses

form CSF
The plexuses are clusters of thin walled capillaries enclosed by a layer of ependymal cells
Слайд 292

Choroid Plexus The capillaries of the choroid plexus are fairly permeable

Choroid Plexus

The capillaries of the choroid plexus are fairly permeable and

tissue fluid filter continuously from the bloodstream
Слайд 293

Choroid Plexus The choroid plexus cells are joined by tight junctions

Choroid Plexus

The choroid plexus cells are joined by tight junctions and

have ion pumps that allow them to modify this filtrate by actively transporting only certain ions across their membranes into the CSF pool
Слайд 294

The Choroid Plexus In adults, the total CSF volume of about

The Choroid Plexus

In adults, the total CSF volume of about 150

ml is replaced every 3-4 hours
900 ml is produced daily
The choroid plexus also helps to cleanse the CSF by removing waste products and other unnecessary solutes
Once produced CSF moves freely through the ventricles
Слайд 295

CSF Circulation Most CSF enters the subarachnoid space via the apertures

CSF Circulation

Most CSF enters the subarachnoid space via the apertures in

the walls of the fourth ventricle
The motion of the CSF is aided by the long microvilli of the ependymal cells lining the ventricles
Some CSF enters the central canal of the spinal cord
Слайд 296

CSF Circulation In the subarachnoid space the CSF bathes the outer

CSF Circulation

In the subarachnoid space the CSF bathes the outer surface

of the brain and cord and then returns to the blood in the dural sinuses via the arachnoid villi
Слайд 297

Blood-Brain Barrier The barrier is a protective mechanism that helps maintain

Blood-Brain Barrier

The barrier is a protective mechanism that helps maintain a

stable environment for the brain
The brain is very dependent on a contant internal environment
Fluctuations in the concentration of ions, hormones, or amino acids, would alter the brain’s function
Hormones and amion acids / neurotransmitters
Ions / neuron thresholds (K+)
Слайд 298

Blood-Brain Barrier Bloodborne substances within the brain’s capillaries are separated from

Blood-Brain Barrier

Bloodborne substances within the brain’s capillaries are separated from the

extra- cellular space and neurons by
Continuous endothelium of the capillary walls
Relatively thick basal lamina surrounding the external face of the capillary
To a limited extend the “feet” of the astrocytes that cling to the capillaries
Слайд 299

Blood-Brain Barrier The capillary endothelial cells are joined almost seamlessly by

Blood-Brain Barrier

The capillary endothelial cells are joined almost seamlessly by tight

junctions
They are the least permeable capillaries in the body
The relative impermeability of brain capillaries accounts for most of the blood brain barrier

Basal lamina (cut)

Слайд 300

Blood-Brain Barrier The blood-brain barrier is a selective, rather than absolute

Blood-Brain Barrier

The blood-brain barrier is a selective, rather than absolute barrier
Nutrients,

such as glucose, essential amino acids, and some electrolytes, move passively by facilitated diffusion through the endothelial cell membranes
Bloodborne metabolic wastes, such as urea and creatinine as well as proteins, certain toxins, and most drugs, are prevented from entering brain tissue
Слайд 301

Blood-Brain Barrier The barrier is ineffective against fats, fatty acids, oxygen,

Blood-Brain Barrier

The barrier is ineffective against fats, fatty acids, oxygen, and

carbon dioxide, and other fat-soluble molecules that diffuse easily through all plasma membranes
This explains why bloodborne alcohol, nicotine, and anesthetics can affect the brain
The barrier is not completely uniform and not completely developed in infants
Слайд 302

Homeostatic Imbalances Traumatic Brain Injuries Concussion / Contusion Cerebrovascular Accidents Strokes

Homeostatic Imbalances

Traumatic Brain Injuries
Concussion / Contusion
Cerebrovascular Accidents
Strokes / Transient ischemic

attacks
Degenerative Brain Diseases
Alzheimer’s Disease / Ach deficits
Parkinson’s Disease / Degeneration of the substantia nigra
Huntington’s Disease / Degeneration of the basal nuclei
- Предыдущая
Data Collection of Primary Central Nervous System (CNS) Tumors
Следующая -
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