chapter 9a
DESCRIPTION
Chapter 9a. The Central Nervous System. About this Chapter. Anatomy of the central nervous system The spinal cord The brain Brain function. The Embryonic Nervous System. The neural tube specializes into the seven major regions of the central nervous system - PowerPoint PPT PresentationTRANSCRIPT
Chapter 9a
The Central Nervous System
About this Chapter
• Anatomy of the central nervous system• The spinal cord• The brain• Brain function
Figure 9-3a
Forebrain Midbrain
Hindbrain
Lumen of neural tube
Spinalcord
The Embryonic Nervous System
• The neural tube specializes into the seven major regions of the central nervous system
• A 4-week human embryo showing the anterior end of the neural tube, which has specialized into three brain regions (a)
The Embryonic Nervous System
• At 6 weeks, the neural tube has differentiated into the brain regions present at birth. The central cavity (lumen) shown in the cross section will become the ventricles of the brain. (see Fig. 9.5)
Figure 9-3b
Cerebrum
Diencephalon
MidbrainEye Medullaoblongata
Spinalcord
(b)
CerebrumDiencephalon
Midbrain
Medullaoblongata
Cerebellumand Pons
Forebrain
Hindbrain
The Embryonic Nervous System
• By 11 weeks of embryonic development, the growth of the cerebrum is noticeably more rapid than that of the other divisions of the brain.
Figure 9-3c
Cerebrum
Diencephalon
Midbrain
Medullaoblongata
Cerebellum
Spinalcord
Pons
(c)
Early Developmental Regions
Late Developmental Regions
Structure Derived from Regions
Thalamus
Encephalons Development
CNS: Bone and Connective Tissue
• Brain is encased in bony skull or cranium• Spinal cord runs through vertebral column• Meninges lies between bone and tissues• Dura mater• Arachnoid membrane• Pia mater• Meningeal layers of the brain cushion and
protect delicate neural tissue
Anatomy of the Central Nervous System
Figure 9-4
Cerebralhemispheres
Cerebellum
Cranium
Cervical spinalnerves
Cranium
Dura mater
Subduralspace
Subarachnoidspace
Pia mater
Arachnoidmembrane
Brain
Thoracic spinalnerves
Lumbar spinalnerves
Sacral spinalnerves
Coccygealnerve
Spinalnerve
Central canal
Spinalnerve
(b) Meningeal layers of the brain cushion and protect delicate neural tissue.
(c) Posterior view of spinal cord and vertebra
(a) Posterior view
Body ofvertebra
Spinalcord
Autonomicganglion
Arachnoidmembrane
Pia mater
Dura mater
White matterGray matter
Meninges
Sectionedvertebrae
CENTRAL NERVOUS SYSTEM SECTIONAL VIEWS OF THE CNS
ANATOMY SUMMARY
Venous sinus
CNS: Gray and White Matter
• Gray matter• Unmyelinated nerve cell bodies• Dendrites• Axon terminals
• White matter• Myelinated axons• Contains very few cell bodies
Thoracic spinalnerves
Lumbar spinalnerves
Sacral spinalnerves
Coccygealnerve
Central canal
Spinalnerve
(c) Posterior view of spinal cord and vertebra
(a) Posterior view
Body ofvertebra
Spinalcord
Autonomicganglion
Arachnoidmembrane
Pia mater
Dura mater
White matterGray matter
Meninges
Sectionedvertebrae
CENTRAL NERVOUS SYSTEM
ANATOMY SUMMARY
Spinalnerve
CNS: Gray and White Matter
Figure 9-4 (2 of 2)
CNS: Gray and White Matter
Figure 9-4c
Spinalnerve
Central canal
Spinalnerve
(c) Posterior view of spinal cord and vertebra
Body ofvertebra
Spinalcord
Autonomicganglion
Arachnoidmembrane
Pia mater
Dura mater
White matterGray matter
Meninges
CENTRAL NERVOUS SYSTEM
ANATOMY SUMMARY
CNS: Bone and Connective Tissue
Figure 9-4 (1 of 2)
Cerebralhemispheres
Cerebellum
Cranium
Cervical spinalnerves
CraniumDura mater
Subduralspace
Subarachnoidspace
Pia mater
Arachnoidmembrane
Brain
(b) Meningeal layers of the brain cushion andprotect delicate neural tissue.
CENTRAL NERVOUS SYSTEM SECTIONAL VIEWS OF THE CNS
ANATOMY SUMMARY
Venous sinus
Dural Sinses• drain CSF • only between dura
CNS: Bone and Connective Tissue
Figure 9-4b
CraniumDura mater
Subduralspace
Subarachnoidspace
Pia mater
Arachnoidmembrane
Brain
(b) Meningeal layers of the brain cushion and protect delicate neural tissue.
CENTRAL NERVOUS SYSTEM
SECTIONAL VIEWS OF THE CNS
ANATOMY SUMMARY
Venous sinus
CNS: Ventricles of the Brain
Figure 9-5a
ANATOMY SUMMARY
VENTRICLES OF THE BRAIN
CerebrumLateral ventricles
Third ventricle
Fourth ventricleCerebellum
Central canalSpinal cord
Lateral view Frontal view(a)
CNS: Cerebrospinal Fluid
Figure 9-5b-d
ANATOMY SUMMARY
CEREBROSPINAL FLUID CIRCULATION
Choroid plexusof third ventricle
Arachnoidvilli
Pia mater
(b)Sinus
Arachnoidmembrane
Arachnoidmembrane
Dura mater
Subarachnoidspace
Central canal
Choroid plexusof fourth ventricleSpinal cord
Cerebralcortex
EndothelialliningBlood invenous sinusFluidmovementArachnoidvillusDura mater(inner layer) Subduralspace
Arachnoidmembrane
Subarachnoidspace
Piamater
Cerebrospinal fluidBone of skullDura mater
(d)
CNS: Cerebrospinal Fluid
Figure 9-5d
ANATOMY SUMMARY
CEREBROSPINAL FLUID CIRCULATION
Cerebralcortex
EndothelialliningBlood invenous sinusFluidmovementArachnoidvillusDura mater(inner layer)Subduralspace
Arachnoidmembrane
Subarachnoidspace
Piamater
Cerebrospinal fluidBone of skullDura mater
(d)
CSF Flow
CNS: Blood-Brain Barrier
Figure 9-6a
(a)
Astrocyte
★★Astrocyte foot processes
secrete paracrines thatpromote tight
junction formation.
Tight junction preventssolute movement
between endothelial cells.
CNS: Blood-Brain Barrier
Figure 9-6b
CNS: Neural Tissue – Metabolic Needs
• Oxygen• Passes freely across blood-brain barrier• Brain receives 15% of blood pumped by heart
• Glucose• Brain responsible for about half of body’s
glucose consumption• Membrane transporters move glucose from
plasma into the brain interstitial fluid• Progressive hypoglycemia leads to confusion,
unconsciousness, and death
Spinal Cord: Overview
Figure 9-4a
Cerebralhemispheres
Cerebellum
Cranium
Cervical spinalnerves
Thoracic spinalnerves
Lumbar spinalnerves
Sacral spinalnerves
Coccygealnerve
(a) Posterior view
Sectionedvertebrae
CENTRAL NERVOUS SYSTEM
ANATOMY SUMMARY
• Central nervous system, posterior view
Spinal Cord: Anatomy
• Specialization in the spinal cord
Figure 9-7a
Gray matter
White matter
(a) One segment of spinal cord,ventral view, showing its pair of nerves.
Dorsal root:carries sensory
(afferent)information
to CNS.Ventral root:carries motor
(efferent) informationto muscles and
glands.
Spinal Cord: Anatomy
Figure 9-7b
(b) Gray matter consists of sensory and motor nuclei.
Dorsal rootganglion
Ventralroot
Ventralhorn
Lateralhorn
Dorsalhorn
Visceral sensory nuclei
Somaticsensorynuclei
Autonomicefferentnuclei
Somaticmotor nuclei
Spinal Cord: Anatomy
• Propriospinal tracts remain within the cord
Figure 9-7c (1 of 2)
Spinal Cord: Anatomy
Figure 9-7c (2 of 2)
Spinal Cord: Integrating Center
Figure 9-8
Stimulus
Response
Command tomuscles or
glands
Sensoryinformation
Sensory informationgoes to the brain
A spinal reflex initiatesa response without input
from the brain.★
Spinalcord
Integratingcenter Interneuron
Anatomy of the Brain
Figure 9-9
Temporallobe
Occipitallobe
Parietallobe
Temporallobe
Parietal lobe
Occipital lobe
Frontal lobe Frontal lobe
(a)
(b) Lateral view of brain
(e) The skull
(c) Mid-sagittal view of brain
(d) Lateral viewof brain stem
CerebellumCerebellum
Medulla oblongata
Medullaoblongata
PonsMedulla oblongata
Pons
Corpus callosumThalamus
Cingulate gyrus
Thalamus
Spinal cord
Cut edges of tractsleading to cerebellum
Midbrain
Cerebrum
Spinalcord
Vertebrae
Parietalbone
Occipitalbone
Frontalbone
Cranialnerves
Optic tractCut edge of
ascendingtracts to
cerebrumPons Temporal
bone
LATERAL VIEWOF THE CNS
ANATOMY OF THE BRAINANATOMY SUMMARY
The Brain: The Brain Stem
• Most cranial nerves originate along brain stem• Cranial nerves can include sensory fibers,
efferent fibers, or both (mixed nerves)• Many nuclei are associated with reticular
formation• Medulla• Somatosensory and corticospinal tracts in
white matter - • Pyramids
The Brain: The Brain Stem
Figure 9-9d
(d) Lateral viewof brain stem
Medullaoblongata
Thalamus
Spinal cord
Cut edges of tractsleading to cerebellum
Midbrain
Cranialnerves
Optic tractCut edge ofascending
tracts tocerebrum
Pons
ANATOMY OF THE BRAIN
ANATOMY SUMMARY
The Brain: Cerebellum
Figure 9-9b
Temporallobe
Occipitallobe
Parietallobe
Frontal lobe
(b) Lateral view of brain
Cerebellum
Medulla oblongata
Pons
ANATOMY OF THE BRAIN
ANATOMY SUMMARY
The Brain: Diencephalon
Figure 9-10
Thalamus
Hypothalamus
Posterior pituitaryAnteriorpituitary
Pinealgland
ThalamusEpithalamusHypothalamus
The Brain: Hypothalamus
• Activates sympathetic nervous system• Maintains body temperature• Controls body osmolarity• Controls reproductive functions• Controls food intake• Interacts with limbic system to influence behavior
and emotions• Influences cardiovascular control center in medulla
oblongata• Secretes trophic hormones that control release
of hormones from anterior pituitary gland
The Brain: Mid-Sagittal View
Figure 9-9c
Temporallobe
Parietal lobe
Occipital lobe
Frontal lobe
(c) Mid-sagittal view of brain
Cerebellum
Medulla oblongata
Pons
Corpus callosumThalamus
Cingulate gyrus
ANATOMY SUMMARY
ANATOMY OF THE BRAIN
The Brain: Gray Matter of the Cerebrum
Figure 9-11
Basalganglia
Lateralventricle
Corpuscallosum
Gray matter ofcerebral cortex
Tip of lateralventricle
Tracts ofwhite matter
The Brain: Cell Bodies in the Cerebral Cortex Form Distinct Layers
Figure 9-12
The Brain: The Limbic System
• Emotion, memory, and learning
Figure 9-13
Thalamus
Hippocampus isinvolved in learningand memory.Amygdala isinvolved in emotionand memory.
Cingulate gyrusplays a rolein emotion.