Anatomy of The Brain 1. 2 Anatomical Organization of the Brain Folds of the Brain Sulcus Groove or...

Anatomy of Anatomy of The BrainThe Brain

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Anatomical Anatomical Organization of the Organization of the

BrainBrainFolds of the Brain

Sulcus•Groove or depression

Gyrus•Ridge

Fissure- Deep Groove

Longitudinal Fissure

Cerebral HemispheresCerebral Hemispheres

Corpus Callosum White matter connecting cerebral hemispheres

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BrainBrainCerebrum

Diencephalon

Cerebellum

Brain Stem

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CerebrumCerebrum

Frontal Lobe

Temporal Lobe

Occipital Lobe

Parietal Lobe

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CerebrumCerebrum

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Frontal Lobe

•Higher Level Thinking & Cognition

•Language Centers• Broca’s Area (Motor Speech)

•Primary Motor Cortex• Execute voluntary movements

CerebrumCerebrum

Temporal Lobe

•Primary Auditory Cortex• Processes auditory stimuli

• Facial Recognition

• Memory

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CerebrumCerebrum

Occipital Lobe

•Primary Visual Cortex• Processes visual stimuli

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CerebrumCerebrum

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Parietal Lobe

•Primary Somatosensory Cortex

• Processes tactile stimuli

Spatial Organization Spatial Organization in the Brainin the Brain

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“Homunculus”


BrainBrainCerebrum

Diencephalon

Cerebellum

Brain Stem

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DiencephaloDiencephalonn

Hypothalamus

Pituitary Gland

Thalamus

Pineal Gland

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Hypothalamus and Pituitary Gland

Key components of the endocrine system

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Pineal Gland

Regulates circadian rhythms (sleep patterns)

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Thalamus

Relay station of the brain

•All sensory input is relayed through the thalamus

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Optic

Nerve

Pathways in the Pathways in the ThalamusThalamus

Retina Thalamus

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Spinal Nerves

& Tracts

Meissner’s Corpuscle

Thalamus

Other Brain Structures

Auditory

Nerve

Auditory Canal Thalamus

Other Areas for

IntegrationOther Areas

for Integration

Optic

Nerve

Pathways in the Pathways in the ThalamusThalamus

Retina Thalamus

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Spinal Nerves

& Tracts

Meissner’s Corpuscle

Thalamus

Other Brain Structures

Auditory

Nerve

Auditory Canal Thalamus

Other Areas for

IntegrationOther Areas

for Integration

Virtually all sensory input passes through the thalamus

Input diverges to many areas of the brain for integration

Pathways of the Visual Pathways of the Visual SystemSystem

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• Visual stimuli received by bipolar cells of retina

• Travels down optic nerve, optic chiasm, &optic tract

Superior Colliculus

Pathways of the Visual Pathways of the Visual SystemSystem

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• Cells synapse in thalamus

• Fibers branch to multiple brain areas

• Visual Cortex

• Sup. Coll.

Superior Colliculus

Limbic systemLimbic system

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Thalamus: Sensory integration

Hypothalamus: Hormone control

Hippocampus: Memory

Amygdala: Emotion and emotional memory

Functionally interconnected brain structures


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Mediates Emotional Responses

Integrates sensory input with emotion, memory, and endocrine output.

Contains ‘pleasure centers’ & ‘Reward pathways’


Brain StemBrain Stem

Attaches to Spinal Cord

Components:•Midbrain•Pons•Medulla

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MidbrainMidbrain

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• Motor Coordination• Visual and auditory

reflexes in the corpora quadrigemina

• Eye Saccades

Eye SaccadesEye Saccades

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• Rapid, involuntary eye movements

• Controlled by superior colliculus & oculomotor nerve III

Pons and MedullaPons and MedullaMotor control of autonomic functions

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Cranial nerves V-XII originate here

• Breathing• Heart rate• Vomiting• Blood pressure


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Thalamus: Sensory integration

Hypothalamus: Hormone control

Hippocampus: Memory

Amygdala: Emotion and emotional memory


CerebellumCerebellumCoordination of movements

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• Fine tune motor activity

• Precise and accurate movements

• Motor memory

Midsaggital view of Midsaggital view of brain structuresbrain structures

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White Matter and White Matter and Gray MatterGray Matter

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Thalamus

Cerebral Cortex

•Diencephalon and Cerebral Cortex are

primarily gray matter (cell bodies & dendrites)

•Fiber tracts (axons) connect structures

together

Cerebral White Matter Cerebral White Matter (Tracts)(Tracts)

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Commisural fibers•Connect two hemispheres

Association Fibers

Cranial NervesCranial Nerves

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OOOTTAFVGVSH

Protection of the Protection of the CNSCNS

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Protection of the CNSProtection of the CNS• Skull and vertebral column• Meninges

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Protection of the CNSProtection of the CNS• Cerebrospinal fluid• Blood brain barrier

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Both systems provide nutrients to the CNS

MeningesMeningesDura Mater (‘Tough Mother’)

External, double-layered covering• Periostium layer-attach to surface of skull• Meningeal layer- outer covering of brain

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MeningesMeningesArachnoid Layer

Middle, web-like layer

Pia LayerInternal, delicate layer

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MeningesMeninges

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Cerebrospinal FluidCerebrospinal Fluid

Fluid contained in the subarachnoid space and ventricles

Functions:•Cushion the brain (buoyancy)•Remove waste products•Supply nutrients

• Transports hormones to other areas of the brain

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Cerebrospinal FluidCerebrospinal FluidChoroid Plexus

• A network of modified ependymal cells that produce and circulate CSF

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Cerebrospinal FluidCerebrospinal FluidCSF circulates through ventricles:

Lateral Third Cerebral aquaduct Fourth Central canal of spinal cord & subarachnoid space

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Cerebrospinal FluidCerebrospinal FluidCSF circulates through ventricles:

Lateral Third Cerebral aquaduct Fourth Central canal of spinal cord & subarachnoid space

CSF drains into the superior sagittal sinus via arachnoid villi

Ventricular SystemVentricular System

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Blood Brain BarrierBlood Brain BarrierSelectively permeable barrier surrounding capillaries in brain

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Prevents passage of potentially harmful substances

Formed by tight junctions between endothelial cells

Blood Brain BarrierBlood Brain Barrier

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Tight junctions between cells prevents diffusion of some molecules in capillary

Blood Brain BarrierBlood Brain Barrier

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Thought QuestionThought Question

Almost all areas of the CNS are protected by the BBB, except the pituitary gland, pineal gland, and hypothalamus.

Why aren’t these areas protected by the BBB?

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The Spinal The Spinal Cord and Cord and ReflexesReflexes

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Anatomy of Spinal Anatomy of Spinal CordCord

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Anatomy of Spinal CordAnatomy of Spinal Cord

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Sensory neurons enter through dorsal root (Afferent)

Motor neurons exit through ventral root (Efferent)

Spinal Interneurons provide quick integration of reflexes

Types of ReflexesTypes of Reflexes

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Autonomic reflexes

Smooth muscle regulation

Heart and blood pressure regulation

Regulation of glands

Digestive system regulation

Somatic reflexes

Activation of skeletal muscles

The Reflex ArcThe Reflex Arc

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Reflex – rapid, predictable, and involuntary responses to stimuli

Reflex arc – direct route from a sensory neuron, to spinal interneuron, to effector

Reflex ArcReflex Arc1. Receptor- Sense stimuli in skin, muscle, etc.

2. Sensory Neuron- Carries impulse toward CNS

3. Interneuron- Quickly integrates in CNS

4. Motor Neuron- Carries impulse away from CNS

5. Effector- Response organ (muscle, gland, etc.)

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Somatic Spinal NervesSomatic Spinal Nerves

Plexus- branching network of

interconnected nerves

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Cauda equina- bundle of spinal nerves inferior to spinal cord


Plexus- branching network of

interconnected nerves

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Thoracic nerves do not form plexus •Innervate thorax and abdomen


Table 7.3

Brachial PlexusFormed lower 4 cervical nerves

Innervates arm and hand•Axillary nerve•Radial nerve•Median nerve•Ulnar nerve


Lumbar PlexusFormed first 4 lumbar nerves

Innervates anterior thigh•Obturator •Femoral

• Lateral & anterior cutaneous


Sacral PlexusFormed first 4 lumbar nerves

Innervates posterior thigh & gluteus, lower leg & foot•Superior & Inferior Gluteal•Posterior femoral cutaneous•Sciatic

• Tibial• Fibular

Autonomic Spinal Autonomic Spinal NervesNerves

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Two antagonistic branches of the ANS

•Effectors: Cardiac & smooth muscle, glands

•Effect same organs, have opposing functions

Autonomic Spinal Autonomic Spinal NervesNerves

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Parasympathetic•Craniosacral origin

Sympathetic•Thoracolumnar origin

Diseases and Diseases and Injuries of the Injuries of the

BrainBrainNeurodegenerative Diseases

Stroke- Brain InjuryPhineus Gage

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Neurodegenerative Neurodegenerative DiseasesDiseases

• Alzheimer’s disease• Huntington’s disease• Multiple Sclerosis• Parkinson’s disease• ALS

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• Progressive death of neurons• Incurable• Most symptoms begin later in life

Alzheimer’s disease Alzheimer’s disease (AD)(AD)

• Most common neurodeg. disease

• Unknown cause (Aging is greatest risk factor)

• Affects memory, thinking, and behavior

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Huntington’s Disease Huntington’s Disease (HD)(HD)

• Relatively rare disease• Affects motor control, behavior, and cognition• Genetic (caused by mutation in DNA)• Symptoms begin ~40 years old

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Multiple Sclerosis Multiple Sclerosis (MS)(MS)

• Breakdown of myelin in brain and spinal cord.

• Unknown cause

• Weakness, numbness, lack of coordination, pain

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StrokeStroke•Cell death from reduced blood flow

•Caused by blocked or ruptured blood vessel

•Often results in motor changes on one side of body

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MRI of Stroke patient

Phineus GagePhineus Gage•Survived construction accident in 1800s

• Iron rod penetrated brain & skull, damaging left frontal lobe

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Phineus GagePhineus Gage• Major behavioral and cognitive changes

• Changed personality• Unchanged sensory &

motor functions

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•Gage allowed us to understand that brain regions have specialized functions

• Frontal lobe responsible for personality & intellect

Review SlidesReview Slides10/15/1510/15/15

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Types of GliaTypes of Glia

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Cell Interaction in Cell Interaction in CNSCNS

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Schwann Schwann

Cell Cell

MyelinationMyelination

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TerminologyTerminology

Nerve: Axons in PNSTract: Axons in CNS

Ganglia: Neuron cell bodies PNSNuclei: Neuron cell bodies in CNS

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Most cell bodies are found in the CNS

Collectively called fibers

Nervous System Nervous System IIII

Julia [email protected]

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Nervous System Nervous System IIIIII

Julia [email protected]

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Anatomy of The Brain 1. 2 Anatomical Organization of the Brain Folds of the Brain Sulcus Groove or...

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