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Principal Parts of the Brain
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Protection The brain is protected by: Cranial bones Cranial meninges Pia, arachnoid, and dura mater Cranial dura mater is composed of 2 layers Cerebrospinal fluid Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Cranial Bones and Meninges
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Extensions of the Dura Mater
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Blood Flow to the Brain Blood flows to the brain via the vertebral and carotid arteries and flows back to the heart via the jugular veins Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Importance of Blood Flow to the Brain
The brain utilizes about 20% of the body’s oxygen supply Any interruption of the oxygen supply can result in weakening, permanent damage, or death of brain cells Glucose deficiency my produce mental confusion, dizziness, convulsions, and unconsciousness Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Blood –Brain Barrier (BBB)
The BBB protects brain cells from harmful substances and pathogens by serving as a selective barrier to prevent passage of many substances from the blood into the brain The BBB can prevent the entry of therapeutic drugs Injury to the brain may cause a breakdown of the BBB, permitting the passage of normally restricted substances into the brain tissue Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Cerebrospinal Fluid (CSF)
CSF is a liquid that protects the brain and spinal cord against chemical and physical injuries and it carries oxygen, glucose, and other important substances from the blood to nervous tissue cells Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Ventricles and the Choroid Plexus
The ventricles of the brain contain CSF The choroid plexuses make CSF Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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CSF Flow Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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The Brain Stem The brain stem is composed of the: Medulla oblongata Pons Midbrain Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Medulla Oblongata The medulla oblongata is continuous with the superior aspect of the spinal cord and contains portions of both motor and sensory tracts Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Medulla Oblongata Structural regions Pyramids – crossing over of motor fibers from the brain/cerebral cortex Functional regions Heart rate, respiratory rate, vasoconstriction, swallowing, coughing, vomiting, sneezing, hiccupping Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Pons The pons is located superior to the medulla oblongata and it links parts of the brain with one another by way of tracts Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Pons Functional regions Relays nerve impulses related to voluntary skeletal muscle movements from cerebrum to cerebellum Pneumotaxic and apneustic areas (control of respiration) Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Midbrain The midbrain is located superior to the medulla oblongata and extends from the pons to the diencephalon Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Midbrain Functional regions Conveys motor impulses from the cerebrum to the cerebellum and spinal cord, sends sensory impulses from the spinal cord to the thalamus, and regulates auditory and visual reflexes Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Reticular Formation The reticular formation helps regulate muscle tone, alerts the cortex to incoming sensory signals, and is responsible for maintaining consciousness and awakening from sleep Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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The Cerebellum The cerebellum occupies the inferior and posterior aspects of the cranial cavity and consists of two hemispheres and a central vermis Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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The Cerebellum The cerebellum functions in the coordination of skeletal muscle contractions and in the maintenance of normal muscle tone, posture, and balance Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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The Diencephalon The diencephalon is composed of the: Thalamus Hypothalamus Epithalamus Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Thalamus –primary sensory relay station
The thalamus is located superior to the midbrain and contains nuclei that serve as relay stations for all sensory impulses (except smell) to the cerebral cortex Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Hypothalamus The hypothalamus is found inferior to the thalamus, has four major regions, controls many body activities, and is one of the major regulators of homeostasis Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Epithalamus The epithalamus lies superior and posterior to the thalamus and contains the pineal gland which secretes melatonin and habenular nuclei which are involved in olfaction Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Circumventricular Organs (CVOs) of the Diencephalon
Parts of the diencephalon, the CVOs, can monitor chemical changes in the blood because they lack a blood-brain barrier CVOs include the hypothalamus (a portion of it), pineal gland, and the pituitary gland CVOs coordinate homeostatic activities of the endocrine and nervous systems Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
The Cerebrum The cerebral cortex is composed of gray matter which contains billions of neurons Gyri, fissures, and sulci can be identified on the cortex Deep to the cortex is white matter composed of tracts of neurons that connect parts of the brain to each other and the spinal cord A bundle of white matter tracts called the corpus callosum connects the right and left hemispheres of the cerebrum Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Anatomical Details of the Cerebral Cortex
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Lobes of the Cerebrum The cerebrum can be divided into the: Frontal lobe Parietal lobe Temporal lobe Occipital lobe Insula Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Cerebral White Matter Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Basal Nuclei of the Cerebrum
The basal nuclei are paired masses of gray matter in each cerebral hemisphere Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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The Limbic System – emotional brain
The limbic system is found in the cerebral hemispheres and diencephalon Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Functional Organization of the Cerebral Cortex
Specific types of sensory, motor, and integrative signals are processed in certain regions of the cerebral cortex. There are: Sensory areas Motor areas Association areas Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Sensory Areas of the Cerebral Cortex
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Sensory Areas of the Cerebral Cortex
Primary Sensory Area – post central gyrus/ parietal lobe Primary Visual Area – occipital lobe Primary Olfactory Area – parietal lobe Primary Auditory Area – temporal lobe Primary Gustatory Area – parietal lobe Wernicke’s Area – temporal lobe in dominant hemisphere, understanding spoken language Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Motor Areas of the Cerebral Cortex
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Motor Areas of the Cerebral Cortex
Primary Motor Area – precentral gyrus/frontal lobe Broca’s Area – motor functions associated with speech in frontal lobe of dominant hemisphere Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Cranial Nerves Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Olfactory, I – pure sensory
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Optic, II – pure sensory Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Oculomotor, III – mixed; motor and sensory to muscles of eyeball
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Trochlear, IV mixed; motor and sensory to muscles of eyeball
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Trigeminal, V - mixed; sensory from face; motor to muscles of face
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Abducens, VI mixed; motor and sensory to muscles of eyeball
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Facial, VII mixed; main motor to muscles of face, sensory for taste anterior 2/3 of tongue Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Vestibulocochlear, VIII – main sensory for hearing
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Glossopharyngeal, IX - mixed; sensory taste from posterior 1/3 of tongue; motor to muscles of swallowing Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Vagus, X - mixed; sensory and motor to muscles of mouth, throat, thoracic and abdominal region Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
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Accessory, XI mixed; sensory and motor to muscles of head and shoulder
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Hypoglossal, XII - mixed; sensory and motor to muscles of swallowing
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