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Chapter 9a

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

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Chapter 9a

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  1. Chapter 9a The Central Nervous System

  2. About this Chapter • Anatomy of the central nervous system • The spinal cord • The brain • Brain function

  3. 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 Hindbrain Spinalcord Forebrain Midbrain Lumen of neural tube (a) Figure 9-3a

  4. Hindbrain Medullaoblongata Cerebellumand Pons Midbrain Forebrain Diencephalon Cerebrum Spinalcord Cerebrum Diencephalon Eye Midbrain Medullaoblongata (b) 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

  5. Cerebrum Diencephalon Midbrain Cerebellum Pons Medullaoblongata Spinalcord (c) 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

  6. Late Developmental Regions Structure Derived from Regions Early Developmental Regions Thalamus

  7. Encephalons Development

  8. CNS: Bone and Connective Tissue • Brain is encased in bony skull or cranium • Spinal cord runs through vertebralcolumn • Meninges lies between bone and tissues • Dura mater • Arachnoid membrane • Pia mater • Meningeal layers of the brain cushion and protect delicate neural tissue

  9. Anatomy of the Central Nervous System ANATOMY SUMMARY CENTRAL NERVOUS SYSTEM SECTIONAL VIEWS OF THE CNS Cranium Cranium Dura mater Cerebralhemispheres Venous sinus Arachnoidmembrane Pia mater Cerebellum Brain Subarachnoidspace Subduralspace Cervical spinalnerves (b) Meningeal layers of the brain cushion and protect delicate neural tissue. Central canal Gray matter White matter Thoracic spinalnerves Spinalnerve Pia mater Arachnoidmembrane Spinalcord Meninges Dura mater Sectionedvertebrae Body ofvertebra Autonomicganglion Lumbar spinalnerves Sacral spinalnerves Spinalnerve Coccygealnerve (c) Posterior view of spinal cord and vertebra (a) Posterior view Figure 9-4

  10. CNS: Gray and White Matter • Gray matter • Unmyelinated nerve cell bodies • Dendrites • Axon terminals • White matter • Myelinated axons • Contains very few cell bodies

  11. CNS: Gray and White Matter ANATOMY SUMMARY CENTRAL NERVOUS SYSTEM Central canal Gray matter White matter Thoracic spinalnerves Spinalnerve Pia mater Spinalcord Arachnoidmembrane Meninges Dura mater Sectionedvertebrae Body ofvertebra Autonomicganglion Lumbar spinalnerves Spinalnerve Sacral spinalnerves Coccygealnerve (c) Posterior view of spinal cord and vertebra (a) Posterior view Figure 9-4 (2 of 2)

  12. CNS: Gray and White Matter ANATOMY SUMMARY CENTRAL NERVOUS SYSTEM Central canal Gray matter White matter Spinalnerve Pia mater Arachnoidmembrane Spinalcord Meninges Dura mater Body ofvertebra Autonomicganglion Spinalnerve (c) Posterior view of spinal cord and vertebra Figure 9-4c

  13. ANATOMY SUMMARY CENTRAL NERVOUS SYSTEM SECTIONAL VIEWS OF THE CNS Cranium Cranium Dura mater Cerebralhemispheres Venous sinus Arachnoidmembrane Pia mater Cerebellum Brain Subduralspace Subarachnoidspace Cervical spinalnerves (b) Meningeal layers of the brain cushion andprotect delicate neural tissue. CNS: Bone and Connective Tissue • Dural Sinses • drain CSF • only between dura Figure 9-4 (1 of 2)

  14. ANATOMY SUMMARY CENTRAL NERVOUS SYSTEM SECTIONAL VIEWS OF THE CNS Cranium Dura mater Venous sinus Arachnoidmembrane Pia mater Brain Subduralspace Subarachnoidspace (b) Meningeal layers of the brain cushion and protect delicate neural tissue. CNS: Bone and Connective Tissue Figure 9-4b

  15. CNS: Ventricles of the Brain ANATOMY SUMMARY VENTRICLES OF THE BRAIN Cerebrum Lateral ventricles Third ventricle Fourth ventricle Cerebellum Central canal Spinal cord (a) Lateral view Frontal view Figure 9-5a

  16. CNS: Cerebrospinal Fluid ANATOMY SUMMARY Cerebrospinal fluid CEREBROSPINAL FLUID CIRCULATION Arachnoidvilli Bone of skull Dura mater Endotheliallining Choroid plexusof third ventricle Blood invenous sinus Fluidmovement Arachnoidvillus Pia mater Cerebralcortex Dura mater(inner layer) Arachnoidmembrane Piamater Subarachnoidspace Arachnoidmembrane Subduralspace (d) (b) Sinus Choroid plexusof fourth ventricle Spinal cord Central canal Subarachnoidspace Arachnoidmembrane Dura mater Figure 9-5b-d

  17. CNS: Cerebrospinal Fluid ANATOMY SUMMARY CEREBROSPINAL FLUID CIRCULATION Cerebrospinal fluid Bone of skull Dura mater Endotheliallining Blood invenous sinus Fluidmovement Arachnoidvillus Cerebralcortex Dura mater(inner layer) Piamater Subarachnoidspace Arachnoidmembrane Subduralspace (d) Figure 9-5d

  18. CSF Flow

  19. CNS: Blood-Brain Barrier ★★ Astrocytefoot processessecrete paracrines thatpromote tightjunction formation. Astrocyte Tight junction preventssolute movementbetween endothelial cells. (a) Figure 9-6a

  20. CNS: Blood-Brain Barrier Figure 9-6b

  21. 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

  22. Cranium ANATOMY SUMMARY Cerebral hemispheres CENTRAL NERVOUS SYSTEM Cerebellum Cervical spinal nerves Thoracic spinal nerves Sectioned vertebrae Lumbar spinal nerves Sacral spinal nerves Coccygeal nerve (a) Posterior view Spinal Cord: Overview • Central nervous system, posterior view Figure 9-4a

  23. White matter Gray matter Dorsal root:carries sensory(afferent)informationto CNS. Ventral root:carries motor(efferent) informationto muscles andglands. (a) One segment of spinal cord,ventral view, showing its pair of nerves. Spinal Cord: Anatomy • Specialization in the spinal cord Figure 9-7a

  24. Visceral sensory nuclei Somaticsensorynuclei Dorsalhorn Dorsal rootganglion Autonomicefferentnuclei Lateralhorn Ventralhorn Ventralroot Somaticmotor nuclei (b) Gray matter consists of sensory and motor nuclei. Spinal Cord: Anatomy Figure 9-7b

  25. Spinal Cord: Anatomy • Propriospinal tracts remain within the cord Figure 9-7c (1 of 2)

  26. Spinal Cord: Anatomy Figure 9-7c (2 of 2)

  27. Spinal Cord: Integrating Center Sensory informationgoes to the brain Spinalcord Stimulus Sensoryinformation Integratingcenter Interneuron Command tomuscles orglands A spinal reflex initiatesa response without inputfrom the brain.★ Response Figure 9-8

  28. Anatomy of the Brain ANATOMY SUMMARY ANATOMY OF THE BRAIN LATERAL VIEWOF THE CNS Frontal lobe Frontal lobe Cingulate gyrus Parietallobe Cerebrum Parietal lobe Corpus callosum Thalamus Occipitallobe Occipital lobe Temporallobe Spinalcord Cerebellum Temporallobe Pons Cerebellum Pons Vertebrae Medulla oblongata Medulla oblongata (b) Lateral view of brain (c) Mid-sagittal view of brain Thalamus Cut edge ofascendingtracts tocerebrum Optic tract Frontalbone Parietalbone Midbrain Pons Temporalbone (a) Cut edges of tractsleading to cerebellum Cranialnerves Occipitalbone Medullaoblongata (d) Lateral viewof brain stem (e) The skull Spinal cord Figure 9-9

  29. 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 • Somatosensoryand corticospinaltracts in white matter - • Pyramids

  30. The Brain: The Brain Stem ANATOMY SUMMARY ANATOMY OF THE BRAIN Thalamus Cut edge ofascendingtracts tocerebrum Optic tract Midbrain Pons Cut edges of tractsleading to cerebellum Cranialnerves Medullaoblongata (d) Lateral viewof brain stem Spinal cord Figure 9-9d

  31. The Brain: Cerebellum ANATOMY SUMMARY ANATOMY OF THE BRAIN Frontal lobe Parietallobe Occipitallobe Temporallobe Pons Cerebellum Medulla oblongata (b) Lateral view of brain Figure 9-9b

  32. The Brain: Diencephalon Thalamus Epithalamus Hypothalamus Thalamus Hypothalamus Pinealgland Anteriorpituitary Posterior pituitary Figure 9-10

  33. 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

  34. The Brain: Mid-Sagittal View ANATOMY SUMMARY ANATOMY OF THE BRAIN Frontal lobe Cingulate gyrus Parietal lobe Corpus callosum Thalamus Occipital lobe Cerebellum Temporallobe Pons Medulla oblongata (c) Mid-sagittal view of brain Figure 9-9c

  35. The Brain: Gray Matter of the Cerebrum Corpuscallosum Basalganglia Lateralventricle Tracts ofwhite matter Tip of lateralventricle Gray matter ofcerebral cortex Figure 9-11

  36. The Brain: Cell Bodies in the Cerebral Cortex Form Distinct Layers Figure 9-12

  37. The Brain: The Limbic System • Emotion, memory, and learning Cingulate gyrusplays a rolein emotion. Thalamus Hippocampus isinvolved in learningand memory. Amygdala isinvolved in emotionand memory. Figure 9-13

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