Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings C h a p t e r 14 The Brain and Cranial Nerves PowerPoint® Lecture Slides prepared by Jason LaPres Lone Star College - North Harris Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings An Introduction to the Brain and Cranial Nerves  The Adult Human Brain  Ranges from 750 cc to 2100 cc  Contains almost 97% of the body’s neural tissue  Average weight about 1.4 kg (3 lb)

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  Four Main Regions of the Brain  Cerebrum  Cerebellum  Diencephalon  Brain Stem 3D Peel-Away of the Brain

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  Cerebrum  Largest part of brain  Controls higher mental functions  Divided into left and right cerebral hemispheres  Surface layer of gray matter (neural cortex)

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  Cerebrum  Neural cortex  Also called cerebral cortex  Folded surface increases surface area  Elevated ridges (gyri)  Shallow depressions (sulci)  Deep grooves (fissures)

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  Cerebellum  Second largest part of brain  Coordinates repetitive body movements  Two hemispheres  Covered with cerebellar cortex

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  Diencephalon  Located under cerebrum and cerebellum  Links cerebrum with brain stem  Three divisions  Left thalamus  Right thalamus  Hypothalamus

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  Diencephalon  Thalamus  Relays and processes sensory information  Hypothalamus  Hormone production  Emotion  Autonomic function  Pituitary gland  Major endocrine gland  Connected to hypothalamus  Via infundibulum (stalk)  Interfaces nervous and endocrine systems

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  The Brain Stem  Processes information between  Spinal cord and cerebrum or cerebellum  Includes  Mesencephalon  Pons  Medulla oblongata

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  The Brain Stem  Mesencephalon  Also called midbrain  Processes sight, sound, and associated reflexes  Maintains consciousness  Pons  Connects cerebellum to brain stem  Is involved in somatic and visceral motor control

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Brain  The Brain Stem  Medulla oblongata  Connects brain to spinal cord  Relays information  Regulates autonomic functions: –heart rate, blood pressure, and digestion

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  Physical protection  Bones of the cranium  Cranial meninges  Cerebrospinal fluid  Biochemical isolation  Blood–brain barrier

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  The Cranial Meninges  Have three layers:  Dura mater  Arachnoid mater  Pia mater  Are continuous with spinal meninges  Protect the brain from cranial trauma

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  The Cranial Meninges  Dura mater  Inner fibrous layer (meningeal layer)  Outer fibrous layer (endosteal layer) fused to periosteum  Venous sinuses between two layers  Arachnoid mater  Covers brain  Contacts epithelial layer of dura mater  Subarachnoid space: between arachnoid mater and pia mater  Pia mater  Attached to brain surface by astrocytes

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  Cerebrospinal Fluid (CSF)  Surrounds all exposed surfaces of CNS  Interchanges with interstitial fluid of brain  Functions of CSF  Cushions delicate neural structures  Supports brain  Transports nutrients, chemical messengers, and waste products

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  Cerebrospinal Fluid (CSF)  CSF circulates  From choroid plexus  Through ventricles  To central canal of spinal cord  Into subarachnoid space around the brain, spinal cord, and cauda equina

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  Blood–Brain Barrier  Isolates CNS neural tissue from general circulation  Formed by network of tight junctions Between endothelial cells of CNS capillaries  Lipid-soluble compounds (O 2, CO 2 ), steroids, and prostaglandins diffuse into interstitial fluid of brain and spinal cord

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  Blood–CSF Barrier  Formed by special ependymal cells  Surround capillaries of choroid plexus  Limits movement of compounds transferred  Allows chemical composition of blood and CSF to differ

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  Four Breaks in the BBB  Portions of hypothalamus  Secrete hypothalamic hormones  Posterior lobe of pituitary gland  Secretes hormones ADH and oxytocin  Pineal glands  Pineal secretions  Choroid plexus  Where special ependymal cells maintain blood– CSF barrier

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Brain Protection and Support  Meninges stabilize brain in cranial cavity  Cerebrospinal fluid protects against sudden movement  CSF provides nutrients and removes wastes  Blood–brain barrier and blood–CSF barrier  Selectively isolate brain from chemicals in blood that might disrupt neural function

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Pons  The Pons  Links cerebellum with mesencephalon, diencephalon, cerebrum, and spinal cord  Sensory and motor nuclei of cranial nerves V, VI, VII, VIII

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Mesencephalon  Structures of the Mesencephalon  Tectum  Two pairs of sensory nuclei (corpora quadrigemina): –superior colliculus (visual) –inferior colliculus (auditory)  Cerebral peduncles  Contain: –descending fibers to cerebellum –motor command fibers

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Diencephalon  Thalamus, epithalamus, and hypothalamus  The pineal gland  Found in posterior epithalamus  Secretes hormone melatonin

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Diencephalon  The Thalamus  The third ventricle  Separates left thalamus and right thalamus  Interthalamic adhesion (or intermediate mass): –projection of gray matter –extends into ventricle from each side

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cerebrum  The Cerebrum  Is the largest part of the brain

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cerebrum  Gray matter  In cerebral cortex and basal nuclei  White matter  Deep to basal cortex  Around basal nuclei

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cerebrum  Structures of the Cerebrum  Gyri  Increase surface area (number of cortical neurons)  Longitudinal fissure  Separates cerebral hemispheres  Lobes  Divisions of hemispheres

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cerebrum  Structures of the Cerebrum  Central sulcus divides  Anterior frontal lobe from posterior parietal lobe  Lateral sulcus divides  Frontal lobe from temporal lobe  Parieto-occipital sulcus divides  Parietal lobe from occipital lobe