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.
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
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
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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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
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)
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.
Copyright © 2007 by Allyn and Bacon Anatomy of Neurons Neurons – structural classes Multipolar Unipolar Bipolar Interneurons
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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
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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Terminology Note CNSPNS Myelin- providing glia Oligodendrocytes Schwann Cells Clusters of cell bodies Nuclei (singular nucleus) Ganglia (singular ganglion) Bundles of axons TractsNerves
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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The Five Divisions of the Brain
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
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
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
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
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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