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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.
Click image to play or pause video
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
Click image to play or pause video
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.
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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
Click image to play or pause video
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
Click image to play or pause video
.
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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
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.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.
Click image to play or pause video
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
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.
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.
Click image to play or pause video
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