Organization of the cns i
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Organization of the CNS I. Phrenology. Review of the Nervous System. MAJOR FUNCTION: COMMUNICATION. Neuronal Morphology. The Neuronal Synapse. Glia – the Particular Role of Astrocytes. Astrocyte. Astrocytes Help Form the Blood Brain Barrier.

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Organization of the CNS I

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Organization of the cns i

Organization of the CNS I


Phrenology

Phrenology


Organization of the cns i

Review of the

Nervous System

MAJOR FUNCTION:

COMMUNICATION


Organization of the cns i

Neuronal Morphology


Organization of the cns i

The Neuronal Synapse


Organization of the cns i

Glia – the Particular Role of Astrocytes


Astrocyte

Astrocyte


Astrocytes help form the blood brain barrier

Astrocytes Help Form the Blood Brain Barrier

  • Basal lamina of the astrocytes + the astrocytic endfeet produce help maintain the BBB.

  • Notice how astrocytes send processes to the external surface of the CNS where the endfeet form the glia limitans externa, which separate the pia mater from the nervous tissue.

  • Gap junctions and desmosomes join the endfeet to form a space between neurons and vascular endothelial cells (Fig. 2.2).


Organization of the cns i

Schwann cells surrounding a (myelinated) axon:


General orientation terms

General Orientation Terms

  • Rostral

  • Caudal

  • Posterior

  • Anterior

  • Dorsal

  • Ventral

  • Sagital

  • Horizontal

  • Coronal


Organization of the cns i

Terms of

Orientation:


Organization of the cns i

Planes of Section:

Horizontal

Transverse (Coronal)

Saggital


Major regions and landmarks

Major regions and landmarks

  • Six regions in the adult brain

    • Cerebrum

    • Diencephalon

    • Mesencephalon

    • Pons

    • Cerebellum

    • Medulla oblongata

  • Brain contains extensive areas of neural cortex

    • Layer of gray matter on the surface of the cerebellum and cerebrum


The adult brain

The Adult Brain


The adult brain1

The Adult Brain


The adult brain2

The Adult Brain


Organization of the cns i

7 Major Divisions of the CNS


A spinal cord

A. Spinal Cord

  • Conduit for flow of information from PNS to CNS.

  • Participates directly in body movement control.

  • Processes sensory information from limbs, trunk, and internal organs.

  • Has segmental organization (most like primitive or early developmental NS).

  • Each segment has a pair of nerve roots.


B brainstem and cerebellum

B. Brainstem and Cerebellum

  • Brainstem = medulla + pons + midbrain.

  • ‘spinal cord’ for the head (sensory, motor control).

    -use of cranial nerves in place of spinal nerves.

    b. Transmission of information between brain and SC.

  • Regulation of arousal (via reticular formation at the core of brainstem).

  • Regulation of important visceral functions (e.g., bp and respiration).


Organization of the cns i

Brain Stem:

Ventral Surface


Organization of the cns i

Brain Stem:

Dorsal Surface


B brainstem and cerebellum1

B. Brainstem and Cerebellum

  • Cerebellum – regulation of movement, maintenance of posture and balance.

    -Works closely in concert with pons (derived from same embryonic brain division).


The cerebellum

The Cerebellum

  • Adjusts postural muscles and tunes on-going movements

  • Cerebellar hemispheres

    • Anterior and posterior lobes

    • Vermis

    • Flocculonodular lobe

  • Superior, middle and inferior cerebellar peduncles link cerebellum with brain stem, diencephalon, cerebrum, and spinal cord

    • Interconnects the two cerebellar hemispheres


The cerebellum1

The Cerebellum


The cerebellum2

The Cerebellum


Organization of the cns i

Cerebellum:


C diencelphalon

C. Diencelphalon

  • Diencephalon – 2nd only to cerebrum as the most highly developed division.

  • Thalamus – key for transmitting information to cerebral hemispheres.

  • Hypothalamus – integrates functions of the ANS – controls endocrine hormone release from pit.


The thalamus

The Thalamus

  • Final relay point for ascending sensory information

  • Coordinates the activities of the cerebral cortex and basal nuclei


Thalamus

Thalamus

  • Part of diencephalon – relay nuclei through which sensory and motor information pass to and from the cortex.

  • E.g., in the 2 1° systems we have discussed:

    - from sc  1° sensory cortex

    - from 1° motor cortex  sc.

  • This is also the case for neural signals controlling other functions, such as learning and memory and emotions – and projecting to other parts of the cortex.

    A. Relay Nuclei have distinct roles, transmitting info from particular subcortical inputs to a specific portion of the cerebral cortex.


The thalamus1

The Thalamus


Organization of the cns i

Thalamus:


The diencephalon and brain stem

The Diencephalon and Brain Stem


The diencephalon and brain stem1

The Diencephalon and Brain Stem


D cerebral hemispheres

D. Cerebral Hemispheres

  • These structures mediate the most complex and sophisticated human behaviors.

  • Cerebral cortex – highly convoluted to accommodate large surface area: gyri, sulci, fissures – deeper grooves – often separate major divisions.

    4 lobes:


Frontal

Frontal

  • Motor behavior

  • The 1° cortex at precentral gyrus.

    -nearby premotor areas

    -prefrontal asociation cortex

    -cingulate gyrus

    - important for reasoning and emotional control.


Parietal

Parietal

  • Sensory areas.

  • The 1° cortex at postcentral gyrus.

    -Superior parietal lobule

    -spatial perception, self-image

    -Inferior parietal lobule

    -integrating sensory information for speech and perception


Occipital

Occipital

  • The 1° cortex within calcarine fissure on medial surface.

  • Surrounding association cortex elaborates the sensory message so that we can see and integrate forms and colours.

  • Situated at the division of parietal and occipital lobes is an area important for recognizing faces.


Temporal

Temporal

  • Sensory functions, plus memory and emotions.

  • The 1° auditory cortex: on superior temporal gyrus – speech centre.

  • Much integration with nearby areas:

    -inferior temporal gyrus – perception of visual forms and colours.

    - works with nearby occipital.

    -temporal pole + medial temporal areas – mediate emotions along with nearby frontal cortical areas.


Ventricles of the brain

Ventricles of the Brain

  • Central passageway of the brain enlarges to form ventricles

    • Contain cerebrospinal fluid (CSF)


Ventricles of the brain1

Ventricles of the Brain


The cranial meninges

The Cranial Meninges

  • Continuous with the three layers of the spinal cord

  • Folds of dura mater help stabilize the position of the brain

    • Falx cerebri

    • Tentorium cerebelli

    • Falx cerebelli


Meninges of the cns

Meninges of the CNS

  • 3 layers:

  • Dura - thickest

  • Arachnoid – “spider-like”

  • Pia – delicate, adheres to surface.

  • Protective

  • Circulating function (contain blood vessels) – many veins and arteries in subarachnoid space.

    Dural sinuses are major venous areas carrying blood away from the brain.


Organization of the cns i

Meninges:


The medulla oblongata and pons

The Medulla Oblongata and Pons


The medulla oblongata and pons1

The Medulla Oblongata and Pons


The mesencephalon

The Mesencephalon

  • The tectum (roof) contains the corpora quadrigemina

    • Superior and inferior colliculi

  • The mesencephalon contains many nuclei

    • Red nucleus

    • Substantia nigra

    • Cerebral peduncles

    • RAS headquarters


The mesencephalon1

The Mesencephalon


The diencephalon is composed of

The Diencephalon is Composed of

  • Epithalamus

  • Hypothalamus

  • Thalamus


Internal capsule

Internal Capsule

  • White matter underling the cortex (seen as a band over the thalamus in sagital section).

  • Path of transmission of info immediate to and from the cortex.


Internal capsule1

Internal Capsule


Internal capsule2

Internal Capsule

  • In the following horizontal section, it lies between the thalamus and the caudate and other basal ganglia (putamen and globus pallidus).


The hypothalamus

The Hypothalamus

  • Controls somatic motor activities at the subconscious level

  • Controls autonomic function

  • Coordinates activities of the endocrine and nervous systems

  • Secretes hormones

  • Produces emotions and behavioral drives

  • Coordinates voluntary and autonomic functions

  • Regulates body temperature

  • Coordinates circadian cycles of activity


The hypothalamus in sagital section

The Hypothalamus in Sagital Section


The hypothalamus in sagital section1

The Hypothalamus in Sagital Section


Organization of the cns i

Hypothalamus:


The basal nuclei

The Basal Nuclei

  • Caudate nucleus

  • Globus pallidus

  • Putamen

    • Control muscle tone and coordinate learned movement patterns


The limbic system

The Limbic System


The brain in section

The Brain in Section


The brain in section1

The Brain in Section


The cerebral cortex

The Cerebral Cortex

  • Surface contains gyri and sulci or fissures

    • Longitudinal fissure separates two cerebral hemispheres

    • Central sulcus separates frontal and parietal lobes

    • Temporal and occipital lobes also bounded by sulci


Laminar organization of the cerebral cortex

Laminar Organization of the Cerebral Cortex

  • All cortical regions are organized in layers.

  • Most cortical regions in humans are the most advanced form (neocortex, isocortex).

  • Allocortex – phylogeneticaly older, has fewer layers: 2 types:

    i. Paleocortex – sense of smell, emotions (olf bulb).

    ii. Archicortex – memories (hipp, 3 layers)


Laminar organization of the cerebral cortex1

Laminar Organization of the Cerebral Cortex

C. Brodmann’s Areas – Thickness of each of the 6 layers varies between these areas, which are also distinct functionally.

Areas that subserve sensation have a thick layer IV (thalamic n. project here)

1° motor areas have a thick layer V.


The white matter of the cerebrum

The White Matter of the Cerebrum


The cerebral hemispheres

The Cerebral Hemispheres

PLAY


Association areas

Association areas

  • Control our ability to understand sensory information and coordinate a response

    • Somatic sensory association area

    • Visual association area

    • Somatic motor association area


General interpretive and speech areas

General Interpretive and Speech Areas

  • General interpretive area

    • Receives information from all sensory areas

    • Present only in left hemisphere

  • Speech center

    • Regulates patterns of breathing and vocalization


Cortex functions and hemispheric differences

Cortex Functions and Hemispheric Differences

  • Prefrontal cortex

    • Coordinates information from secondary and special association areas

    • Performs abstract intellectual functions

  • Hemispheric differences

    • Left hemisphere typically contains general interpretive and speech centers and is responsible for language based skills

    • Right hemisphere is typically responsible for spatial relationships and analyses


Hemispheric lateralization

Hemispheric Lateralization

PLAY


Focus cranial nerves

Focus: Cranial Nerves

  • 12 pairs of cranial nerves

    • Each attaches to the ventrolateral surface of the brainstem near the associated sensory or motor nuclei


Origins of the cranial nerves

Origins of the Cranial Nerves

PLAY


Origins of the cranial nerves1

Origins of the Cranial Nerves

PLAY


Origins of the cranial nerves2

Origins of the Cranial Nerves

PLAY


The limbic system or motivational system includes

The Limbic System or Motivational System includes

  • Amygdaloid body

  • Cingulated gyrus

  • Parahippocampal gyrus

  • Hippocampus

  • Fornix

  • Functions of the limbic system involved emotions and behavioral drives


The cerebral cortex1

The Cerebral Cortex

  • Surface contains gyri and sulci or fissures

    • Longitudinal fissure separates two cerebral hemispheres

    • Central sulcus separates frontal and parietal lobes

    • Temporal and occipital lobes also bounded by sulci


White matter of the cerebrum

White Matter of the Cerebrum

  • Contains association fibers

  • Commissural fibers

  • Projection fibers


Association areas1

Association Areas

  • Control our ability to understand sensory information and coordinate a response

    • Somatic sensory association area

    • Visual association area

    • Somatic motor association area


General interpretive and speech areas1

General Interpretive and Speech Areas

  • General interpretive area

    • Receives information from all sensory areas

    • Present only in left hemisphere

  • Speech center

    • Regulates patterns of breathing and vocalization


Cortex functions and hemispheric differences1

Cortex Functions and Hemispheric Differences

  • Prefrontal cortex

    • Coordinates information from secondary and special association areas

    • Performs abstract intellectual functions

  • Hemispheric differences

    • Left hemisphere typically contains general interpretive and speech centers and is responsible for language based skills

    • Right hemisphere is typically responsible for spatial relationships and analyses


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