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The Brain and Cranial Nerves

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14 The Brain and Cranial Nerves PowerPoint® Lecture Presentations prepared by Jason LaPres Lone Star College—North Harris © 2012 Pearson Education, Inc. An Introduction to the Brain and Cranial Nerves • Learning Outcomes • 14-1 Name the major brain regions, vesicles, and ventricles, and describe the locations and functions of each. • 14-2 Explain how the brain is protected and supported, and discuss the formation, circulation, and function of cerebrospinal fluid. • 14-3 Describe the anatomical differences between the medulla oblongata and the spinal cord, and identify the main components and functions of the medulla oblongata. © 2012 Pearson Education, Inc. An Introduction to the Brain and Cranial Nerves • Learning Outcomes • 14-4 List the main components of the pons, and specify the functions of each. • 14-5 List the main components of the cerebellum, and specify the functions of each. • 14-6 List the main components of the midbrain, and specify the functions of each. • 14-7 List the main components of the diencephalon, and specify the functions of each. © 2012 Pearson Education, Inc. An Introduction to the Brain and Cranial Nerves • Learning Outcomes • 14-8 Identify the main components of the limbic system, and specify the locations and functions of each. • 14-9 Identify the major anatomical subdivisions and functions of the cerebrum, and discuss the origin and significance of the major types of brain waves seen in an electroencephalogram. • 14-10 Describe representative examples of cranial reflexes that produce somatic responses or visceral responses to specific stimuli. © 2012 Pearson Education, Inc. • In the pre-synaptic neuron, an Synapse electrical signal comes in, opens up to voltage-gated channels, and signals the vesicles containing neurotransmitters (chemical signal) to be released into the synaptic cleft. Pre-synaptic neuron • Receptors on the post-synaptic neuron bind to the neurotransmitter signaling it to open its gate and let ions flow through. • The flow of ions will generate a current that changes the resting Synaptic cleft membrane potential. If the membrane Glutam potential passes the threshold, then ate an action potential is produced. • The action potential is then propagated to the next neuron, and Post-synaptic the communication continues from neuron neuron to neuron. AMP NMD AR AR Picture adapted from MRC Centre for Synaptic Plasticity © 2012 Pearson Education, Inc. 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) © 2012 Pearson Education, Inc. Brain Summary • Important component of the CNS. • Site for coordination and integration of sensations, emotions, memory, and behavior. • Divided into 6 regions (cerebrum, cerebellum, diencephalon, mesencephalon, pons, and medulla oblongata) • Protected by 3 connective tissue meninges: dura mater, arachnoid, and the pia mater—just like the spinal cord. • Large blood vessels called dural sinuses can be found between 2 layers of dura mater. • The subarachnoid space is filled with CSF • Cranial nerves emerge from various parts of the brain • The brain contains both gray matter and white matter • Gray = interneurons and neuroglia • White = fiber tracts © 2012 Pearson Education, Inc. 14-1 The Brain • Six Regions of the Brain 1. Cerebrum 2. Cerebellum 3. Diencephalon 4. Mesencephalon (midbrain) 5. Pons Brain Stem 6. Medulla oblongata © 2012 Pearson Education, Inc. 14-1 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) © 2012 Pearson Education, Inc. 14-1 The Brain • Cerebrum • Neural cortex • Also called cerebral cortex • Folded surface increases surface area • Elevated ridges (gyri) • Shallow depressions (sulci) • Deep grooves (fissures) © 2012 Pearson Education, Inc. 14-1 The Brain • Cerebellum • Second largest part of brain • Coordinates repetitive body movements • Two hemispheres • Covered with cerebellar cortex © 2012 Pearson Education, Inc. Figure 14-1 An Introduction to Brain Structures and Functions Left cerebral hemisphere Gyri CEREBRUM Sulci • Conscious thought processes, Fissures intellectual functions • Memory storage and processing • Conscious and subconscious regulation of skeletal muscle contractions CEREBELLUM • Coordinates complex Spinal somatic motor cord patterns • Adjusts output of other somatic motor centers in brain and spinal cord © 2012 Pearson Education, Inc. 14-1 The Brain • Diencephalon • Located under cerebrum and cerebellum • Links cerebrum with brain stem • Three divisions of the diencephalon 1. Epithalamus 2. thalamus 3. Hypothalamus © 2012 Pearson Education, Inc. 14-1 The Brain • Diencephalon • Thalamus • Relays and processes sensory information • Hypothalamus • Hormone production • Emotion • Autonomic function © 2012 Pearson Education, Inc. 14-1 The Brain • Diencephalon • Pituitary gland • Major endocrine gland • Connected to hypothalamus © 2012 Pearson Education, Inc. 14-1 The Brain • The Brain Stem • Processes information between: • Spinal cord and cerebrum or cerebellum • Includes: • Midbrain • Pons • Medulla oblongata © 2012 Pearson Education, Inc. 14-1 The Brain • Midbrain • Also called mesencephalon • Processes sight, sound, and associated reflexes • Maintains consciousness • Pons • Connects cerebellum to brain stem • Is involved in somatic and visceral motor control © 2012 Pearson Education, Inc. 14-1 The Brain • Medulla Oblongata • Connects brain to spinal cord • Relays information • Regulates autonomic functions • Heart rate, blood pressure, and digestion © 2012 Pearson Education, Inc. Figure 14-1 An Introduction to Brain Structures and Functions DIENCEPHALON THALAMUS • Relay and processing centers for sensory information HYPOTHALAMUS • Centers controlling emotions, autonomic functions, and hormone production MIDBRAIN Brain • Processing of visual stem and auditory data • Generation of reflexive somatic motor responses • Maintenance of consciousness PONS • Relays sensory MEDULLA OBLONGATA information to cerebellum and • Relays sensory information to thalamus and thalamus to other portions of the brain stem • Subconscious • Autonomic centers for regulation of visceral somatic and visceral function (cardiovascular, respiratory, and motor centers digestive system activities) © 2012 Pearson Education, Inc. 14-1 The Brain • Ventricles of the Brain • Within the brain are 4 spaces called ventricles • 2 lateral ventricles • Third ventricle • Fourth ventricle • Connects with third ventricle via narrow canal in midbrain called the cerebral aqueduct © 2012 Pearson Education, Inc. Figure 14-2a Ventricles of the Brain Cerebral hemispheres Ventricles of the Brain Lateral ventricles Third ventricle Cerebral aqueduct Fourth ventricle Pons Medulla oblongata Spinal cord Central canal Ventricular system, lateral view © 2012 Pearson Education, Inc. Figure 14-2b Ventricles of the Brain Ventricles of Cerebral hemispheres the Brain Lateral ventricles Third ventricle Fourth ventricle Central canal Cerebellum Ventricular system, anterior view © 2012 Pearson Education, Inc. 14-1 The Brain • The Brain • The brain is a large, delicate mass of neural tissue • Containing internal passageways and chambers filled with cerebrospinal fluid • Each of the six major brain regions has specific functions • Ascending from the medulla oblongata to the cerebrum, brain functions become more complex and variable • Conscious thought and intelligence • Are produced in the neural cortex of the cerebral hemispheres © 2012 Pearson Education, Inc. 14-2 Brain Protection and Support • Physical Protection of the Brain • Bones of the cranium • Cranial meninges • Cerebrospinal fluid • Biochemical Isolation • Blood–brain barrier © 2012 Pearson Education, Inc. 14-2 Brain Protection and Support • The Cranial Meninges • Have three layers 1. Dura mater 2. Arachnoid mater 3. Pia mater • Are continuous with spinal meninges • Protect the brain from cranial trauma © 2012 Pearson Education, Inc. 14-2 Brain Protection and Support • The Cranial Meninges • Dura mater • Inner fibrous layer • 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 © 2012 Pearson Education, Inc. 14-2 Brain Protection and Support • Dural Folds • Folded inner layer of dura mater • Extend into cranial cavity • Stabilize and support brain • Contain collecting veins (dural sinuses) © 2012 Pearson Education, Inc. Figure 14-3a The Relationship among the Brain, Cranium, and Meninges Dura mater (endosteal layer) Dural sinus Cranium (skull) Dura mater (meningeal layer) Subdural space Arachnoid mater Subarachnoid space Arachnoid trabeculae Pia mater Cerebral cortex Cerebral cortex Cerebellum Medulla oblongata Spinal cord A lateral view of the brain, showing its position in the cranium and the organization of the meninges © 2012 Pearson Education, Inc. 14-2 Brain Protection and Support • Cerebrospinal Fluid (CSF) – subarachnoid space is filled with 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 © 2012 Pearson Education, Inc. 14-2 Brain Protection and Support • Cerebrospinal Fluid (CSF) • Choroid plexus—site of CSF production • Specialized ependymal
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