1. Copyright © 2007 by Allyn and Bacon Chapter 2 The Anatomy of the Brain The Systems, Structures, and Cells that Make Up Your Nervous System This multimedia product and its contents are protected under copyright law. The following are prohibited by law: any public performance or display, including transmission of any image over a network; preparation of any derivative work, including the extraction, in whole or in part, of any images; any rental, lease, or lending of the program.

2. Copyright © 2007 by Allyn and Bacon General Layout of the Nervous System Central Nervous System (CNS)  Brain (in the skull)  Spinal Cord (in the spine) Peripheral Nervous System (PNS)  Located outside of the skull and spine  Serves to bring information into the CNS and carry signals out of the CNS

3. Copyright © 2007 by Allyn and Bacon General Layout of the Nervous System PNS – 2 divisions  Somatic Nervous System  Afferent nerves (sensory)  Efferent nerves (motor)  Autonomic Nervous System  Sympathetic and parasympathetic nerves

4. Copyright © 2007 by Allyn and Bacon Autonomic Nervous System Sympathetic “fight or flight” Second stage neurons are far from the target organ Parasympathetic “rest and restore” Second stage neurons are near the target organ

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6. Meninges, Ventricles, and CSF CNS - encased in bone and covered by three meninges  Dura mater - tough outer membrane  Arachnoid membrane - weblike  Pia mater - sticks to CNS surface Cerebrospinal fluid (CSF)  Fluid serves as cushion

7. Copyright © 2007 by Allyn and Bacon Protecting the Brain Chemical protection  The blood-brain barrier – tightly-packed cells of blood vessel (endothelial cells) walls prevent entry of many molecules Physical protection  Skull  Meninges  Cerebrospinal fluid (CSF)

8. Copyright © 2007 by Allyn and Bacon Cells of the Nervous System Generally two types Neurons – specialized for reception, conduction, and transmission Glial cells – Support cells; outnumber neurons by 10 to 1.

9. Copyright © 2007 by Allyn and Bacon Anatomy of Neurons Neurons – structural classes  Multipolar  Unipolar  Bipolar  Interneurons

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11. Anatomy of Neurons Nuclei – clusters of cell bodies in the CNS Ganglia – clusters of cell bodies in the PNS Tracts – bundles of axons in the CNS Nerves – bundles of axons in the PNS

12. Copyright © 2007 by Allyn and Bacon Glial Cells: The Forgotten Majority Myelin producers  Oligodendrocytes (CNS)  Schwann cells (PNS) Astrocytes – largest, many functions (composed the blood-brain barrier) Microglia – smallest, involved in response to injury or disease

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14. Terminology Note CNSPNS Myelin- providing glia Oligodendrocytes Schwann Cells Clusters of cell bodies Nuclei (singular nucleus) Ganglia (singular ganglion) Bundles of axons TractsNerves

15. Copyright © 2007 by Allyn and Bacon Neuroanatomical Directions Anterior (rostral) – towards the nose Posterior (caudal) – towards the tail Dorsal – towards the surface of the back or the top of the head Ventral – towards the surface of the chest or the bottom of the head

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18. The Five Divisions of the Brain

19. Copyright © 2007 by Allyn and Bacon Major Structures of the Brain Myelencephalon = medulla  Composed largely of tracts  Origin of the reticular formation Metencephalon  Many tracts  Pons – ventral surface  Cerebellum - coordination

20. Copyright © 2007 by Allyn and Bacon Major Structures of the Brain Mesencephalon  Tectum (dorsal surface) Inferior colliculi – audition Superior colliculi - vision  Tegmentum (ventral) – 3 ‘colorful’ structures Periaqueductal gray – analgesia Substantia nigra – sensorimotor Red nucleus– sensorimotor

21. Copyright © 2007 by Allyn and Bacon Major Structures of the Brain Diencephalon  Thalamus – sensory relay nuclei  Hypothalamus  Regulation of motivated behaviors  Controls hormone release by the pituitary Telencephalon  Cerebral cortex  Limbic system  Basal ganglia

22. Copyright © 2007 by Allyn and Bacon Telencephalon – Cerebral Cortex Convolutions serve to increase surface area. Longitudinal fissure – a groove that separates right and left hemispheres Corpus callosum – largest hemisphere-connecting tract

23. Copyright © 2007 by Allyn and Bacon Limbic System Regulation of motivated behaviors “a circuit of midline structures that circle the thalamus” Consists of  Primitive cortex - hippocampus and cingulated cortex  Subcortical structures - mammillary bodies, amygdala, fornix, septum

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