brain lecture by bl

8/6/2019 Brain Lecture by BL

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The Human Brain:The Human Brain:

Anatomy,Anatomy,

Functions,Functions,and Injuryand Injury

Main MenuMain Menu

Brain Anatomy

Brain Functions

Injury Mechanisms

Brain Anatomy MenuBrain Anatomy MenuSkull Anatomy

Interior Skull Surface

Blood Vessels of the Brain

Arteries of the Brain

The Neuron

The Meninges

External Brain Structures

The Cerebrum

The Limbic System

Cerebellum

Thalamus

Hypothalamus

The Medulla Oblongata

The Pons

The Ventricles

Cerebrospinal Fluid

The Cerebrum The Cortex

The Neocortex

Lobes of the Cerebrum

Frontal Lobe

Temporal Lobe

Parietal Lobe

Occipital Lobe

Limbic Lobe

The Brainstem

Brainstem Components

Brainstem Divisions

The Cranial Nerves

Skull AnatomySkull Anatomy

The skull is a rounded layer ofbone designed to protect the brainfrom penetrating injuries.

Blood Vessels of the Skull

Rough Interior of Skull

Interior Skull SurfaceInterior Skull Surface

The base of the skull is rough,with many bony protuberances.

These ridges can result in injuryto the temporal lobe of the brainduring rapid acceleration.

Bony ridges

Injury from contactwith skull

Blood Vessels of the SkullBlood Vessels of the Skull

The brain requires a rich bloodsupply, and the space betweenthe skull and cerebrum containsmany blood vessels.

These blood vessels can be

ruptured during trauma,resulting in bleeding.

Groove for middlemeningeal artery


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Arteries of the BrainArteries of the Brain

The human brain requires a

constant supply of oxygen. A

lack of oxygen of just a fewminutes results in irreversibledamage to the brain.

The NeuronThe Neuron

Dendrites:Collects informationfrom other neurons.

Cell Body

Axon:Transmits informationto other neurons.

Click image to play or pause video

The MeningesThe Meninges

The meninges are layersof tissue that separate theskull and the brain.

Skull

Dura mater

Arachnoid Layer

Pia Mater

Brain

External Brain StructuresExternal Brain Structures

The CerebrumThe Cerebrum

The largest portion of the brainis the cerebrum. It consists oftwo hemispheres that areconnected together at thecorpus callosum.

The cerebrum is often divided

Corpus callosum

into five lobes that areresponsible for different brainfunctions.

The CerebrumThe Cerebrum

Neocortex

The cerebrums surfacethe

neocortexis convoluted intohundreds of folds.

The neocortex is where all the

higher brain functions take place.


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The NeocortexThe Neocortex

The cerebral cortex is a thin layer of cells about 1.5 to4 mm thick.

The cortex provides the connections and pathwaysfor the highest cognitive functions, such as languageand abstract thinking.

The cerebral cortex contains about 25 billion neurons,more than 62,000 miles of axons, and300,000,000,000,000 synapses.

Neocortex layer

The thin layer of theneocortex is densewith neurons.

Lobes of the CerebrumLobes of the Cerebrum

Frontal Lobe

Limbic Lobe

Parietal Lobe

Temporal Lobe

Occipital Lobe

Frontal LobeFrontal Lobe

The frontal lobe is the area ofthe brain responsible for

higher cognitive functions.

These include:

Problem solving Spontaneity emory Language Motivation Judgment Impulse control Social and sexual behavior.

Temporal LobeTemporal Lobe

The temporal lobe plays arole in emotions, and isalso responsible forsmelling, tasting,perception, memory,understanding music,

aggressiveness, andsexual behavior.

The temporal lobe alsocontains the languagearea of the brain.

Parietal LobeParietal LobeThe parietal lobe plays arole in our sensations oftouch, smell, and taste. It

also processes sensoryand spatial awareness,and is a key componentin eye-hand co-ordination

.

The parietal lobe alsocontains a specializedarea called Wernickes

area that is responsiblefor matching writtenwords with the sound ofspoken speech.

Occipital LobeOccipital Lobe

The occipital lobe is atthe rear of the brainand controls visionand recognition.


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Limbic LobeLimbic Lobe

The limbic lobe islocated deep in thebrain, and makes up

the limbic system.

The Limbic SystemThe Limbic System

The limbic system is thearea of the brain thatregulates emotion and

memory. It directlyconnects the lower andhigher brain functions.

A. Cingulate gyrusB. FornixC. Anterior thalamic

nucleiD. HypothalamusE. Amygdaloid nucleusF. Hippocampus

CerebellumCerebellum

The cerebellum is connected to thebrainstem, and is the center forbody movement and balance.


ThalamusThalamusThalamus means inner room in Greek,as it sits deep in the brain at the top ofthe brainstem.

The thalamus is called the gateway tothe cerebral cortex, as nearly allsensory inputs pass through it to thehigher levels of the brain.

HypothalamusHypothalamus

The hypothalamus sits under the thalamus at

the top of the brainstem. Although thehypothalamus is small, it controls many criticalbodily functions:

Controls autonomic nervous system

Centerfor emotional res onse andbehavior

Regulates body temperature

Regulates food intake

Regulates water balance and thirst

Controls sleep-wake cycles

Controls endocrine system

The hypothalamus isshaded blue. The pituitarygland extends from thehypothalamus.

The Medulla OblongataThe Medulla Oblongata

The medulla oblongata merges

seamlessly with the spinal cord andcreates the base of the brainstem.

The medulla is primarily a controlcenter for vital involuntary reflexes

such as swallowing, vomiting,sneezng, coug ng, an reguaton ocardiovascular and respiratory activity.

The medulla is also the origin of manycranial nerves.


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The Cranial NervesThe Cranial Nerves

I . Olfactory nerve

II. Optic nerve

III. Oculomotor nerveIV. Trochlear nerveV. Trigeminal nerveVI. Abducens nerve

.VIII. Vestibulocochlear nerveIX. Glossopharyngeal nerveX. Vagus nerveXI. Accessory nerveXII. Hypoglossal nerve

Injury MechanismsInjury Mechanisms

The brain is a complex and delicate organ, and onethat is vulnerable to injury from a variety of differenttraumas. These include:

Frontal Lobe Injury

Occipital Lobe Injury

empora o e n ury

Side Impact Injury

Coup/Contre-coup Injury

Diffuse Axonal Injury

Epidural Hematoma

Subdural Hematoma

Frontal Lobe InjuryFrontal Lobe Injury

The frontal lobe of the brain can beinjured from direct impact on thefront of the head.

During impact, the brain tissue isaccelerated forward into the bonyskull. This can cause bruising of


blood vessels.

Frontal lobe injuries can causechanges in personality, as well asmany different kinds ofdisturbances in cognition andmemory.

Occipital Lobe InjuryOccipital Lobe Injury

Occipital lobe injuriesoccur from blows to theback of the head.

This can cause bruisingof the brain tissue andtearing of blood vessels.


These injuries can resultin vision problems oreven blindness.

Temporal Lobe InjuryTemporal Lobe Injury

The temporal lobe of the brain isvulnerable to injury from impactsof the front of the head.

The temporal lobe lies upon thebony ridges of the inside of the

skull, and rapid acceleration can


into the bone, causing tissuedamage or bleeding.

Side Impact InjurySide Impact Injury

Injuries to the right or left sideof the brain can occur frominjuries to the side of the head.

Injuries to this part of the braincan result in language or

speech difficulties, and


.


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Coup/ContreCoup/Contre--coup Injurycoup Injury

A French phrase that describesbruises that occur at two sitesin the brain.

When the head is struck, theimpact causes the brain tobump the opposite side of the


.area of impact and on theopposite side of the brain.

Diffuse Axonal InjuryDiffuse Axonal Injury

Brain injury does not require adirect head impact. Duringrapid acceleration of the head,

some parts of the brain canmove separately from otherparts. This type of motioncreates shear forces that can

destroy axons necessary forbrain functioning.

These shear forces can stretchthe nerve bundles of the brain.

More on diffuse axonal injury.


Diffuse Axonal InjuryDiffuse Axonal InjuryThe brain is a complexnetwork of interconnections.Critical nerve tracts can besheared and stressed duringan acceleration-type of injury.

Diffuse axonal injury is a very seriousinjury, as it directly impacts the majorpathways of the brain.

Epidural HematomaEpidural Hematoma

An epidural hematoma is ablood clot that forms betweenthe skull and the top lining ofthe brain (dura).

This blood clot can cause fastchanges in the pressure inside


.

When the brain tissue iscompressed, it can quicklyresult in compromised bloodflow and neuron damage.

Subdural HematomaSubdural Hematoma

A subdural hematoma is ablood clot that forms betweenthe dura and the brain tissue.

The clot may cause increasedpressure and may need to be

removed surgically.


When the brain tissue iscompressed, it can quicklyresult in compromised blood

flow and tissue damage.

Brain FunctionsBrain Functions

Vision

Taste Cognition Emotion Speech Language Hearin Motor Cortex Sensory Cortex Autonomic Functions


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VisionVision

The visual cortex resides in theoccipital lobe of the brain.

Sensory impulses travel fromthe eyes via the optic nerve tothe visual cortex.

Dama e tothevisual cortexcan result in blindness.

TasteTaste

The gustatory complex(green circle) is the partof the sensory cortex(purple area) that isresponsible for taste.

CognitionCognition

The prefrontal cortex isinvolved with intellect,complex learning, andpersonality.

Injuries to the front lobe

can cause mental andpersona ty c anges.

EmotionEmotion

Emotions are an extremelycomplex brain function. Theemotional core of the brain is thelimbic system. This is wheresenses and awareness are firstprocessed in the brain.

Prefrontal cortex

oo an persona ty aremediated through the prefrontalcortex. This part of the brain isthe center of higher cognitive andemotional functions. Limbic system

SpeechSpeech

Brocas area is where we

formulate speech and thearea of the brain that sendsmotor instructions to themotor cortex.

Injury to Brocas area can

Brocas Area

cause cuty n spea ng.The individual may knowwhat words he or she wishesto speak, but will be unable

to do so.

LanguageLanguage

Wernickes area is a

specialized portion of theparietal lobe that recognizesand understands written andspoken language.

Wernickes area surrounds the

Auditory Association Area

au tory assocat on area.

Damage to this part of thebrain can result in someonehearing speech, but notunderstanding it.

Wernickes Area


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HearingHearingThere are two auditoryareas of the brain:

The primary auditory

area (brown circle) is whatdetects sounds that aretransmitted from the ear. Itis located in the sensorycortex.

The auditory associationarea (purple circle) is thepart of the brain that is

used to recognize thesounds as speech, music,or noise.

Motor CortexMotor CortexThe motor portion of the

cerebrum is illustrated here. Thelight red area is the premotorcortex, which is responsible for

repetitive motions of learnedmotor skills. The dark red area isthe primary motor area, and isresponsible for control ofskeletal muscles.

Different areas of the brain are

associated with different parts ofthe body.

Injury to the motor cortex can

result in motor disturbance in theassociated body part.

Sensory CortexSensory CortexThe sensory portion of thecerebrum is illustrated here.

Different areas of the brain areassociated with different parts ofthe body, as can be seen below.

Injury to the sensory cortex canresult in sensory disturbance inthe associated body part.

Autonomic FunctionsAutonomic FunctionsThe brainstem controls the basicfunctions of life. Damage to theseareas of the brain are usuallyfatal:

The pons plays a critical role inrespiration.

responsible for respiration andcardiovascular functions.

Pons

Medulla Oblongata

BibliographyBibliography

The following are excellent resources and were the basis of the anatomical andfunctional components of this presentation:

The Human Brain: An Introduction to Its Functional Anatomy, Fifth Edition. JohnNolte, Mosby, 2002. ISBN: 0-323-01320-1 Purchase Here

Coping with Mild Traumatic Brain Injury. Dr. Diane Stoler, Avery Penguin Putnam,1998. ISBN: 0895297914 Purchase Here

uman naomy an ysoogy, on. ane . are ,

Benjamin/Cummings, 2000. ISBN: 0805349898. Purchase Here

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