Central Nervous System - The Brain PDF

Central Nervous System The Brain  General Terminology Rostral Caudal Gyri (singular, gyrus) = folds Sulci (singular, sulcus) = grooves – Central sulcus – Parieto-occipital sulcus – Lateral sulcus Fissures = deeper grooves – Longitudinal Fissure...

Central Nervous System The Brain  General Terminology Rostral Caudal Gyri (singular, gyrus) = folds Sulci (singular, sulcus) = grooves – Central sulcus – Parieto-occipital sulcus – Lateral sulcus Fissures = deeper grooves – Longitudinal Fissure – Transverse Fissure Corpus callosum  General Terminology Major Portions – Cerebrum – Brainstem (green) – Diencephalon (purple) – Cerebellum  Gray and White Matter Gray Matter – Cerebral cortex – Neuron cell bodies (nuclei), Dendrites, Synapses – Unmyelinated White Matter – Deep – Tracts – bundles of axons – Myelinated  Meninges Dura Mater Arachnoid Mater Pia Mater  Dura mater – Periosteal layer Meninges – Meningeal layer Falx cerebri Tentorium cerebelli Falx cerebelli – Dural sinus Superior sagittal sinus Transverse sinus  Arachnoid mater Meninges – Subarachnoid space Pia mater  Ventricles Cerebrospinal Fluid Circulation – 4 Fluid filled chambers – Continuous to one another and to central canal of spinal cord Lateral ventricles (2) – Interventricular foramen (2) Third ventricle – Cerebral aqueduct Fourth ventricle – Lateral, median apertures – Central canal Ventricles Choroid Plexus – Blood capillary mass – Ependymal cells  Cerebrospinal Fluid (CSF) Clear, colorless liquid Ventricles and canals of CNS Flows through and around CNS Absorbed by arachnoid granulations (villi) – growths of arachnoid mater into the dural sinuses  Video Test your ability to walk someone through the flow of CSF through the brain and into the spinal cord Purposes of Cerebrospinal Fluid Buoyancy – Brain hangs from fibroblast – Brain weighs 1500 g; in CSF 50 g Protection – Keep brain from striking cranium – Brain injuries still occur Shaken baby syndrome/concussions Chemical stability – Rinses metabolic waste Removal of Wastes by Venous Blood Figure 12.24a  Blood Brain Barrier (BBB) Least permeable capillaries in body Endothelial cells – Tight junctions Astrocytes surround capillaries signal endothelial cells to make tight junctions www.studyblue.com  Blood Brain Barrier (BBB) What passes through? What doesn’t? Glucose Blood-borne metabolic waste O2 , CO2 Blood cells Lipids K+ ions Select drugs - Alcohol, Nicotine, Certain toxins Caffeine Most drugs Anesthetics  Major Brain Portions Cerebrum Diencephalon (purple) Brainstem (green) Cerebellum  Cerebrum Largest, most obvious Higher brain functions – Perception – Storage – Processing and Reasoning – Instinctual and Emotional Left and Right Hemispheres – Longitudinal fissure – White fibrous tracts – Corpus callosum – Cerebral gyri and sulci  Cerebral Hemispheres Four major divisions – White matter internally – Basal nuclei deep within white matter – Limbic system – Cerebral cortex of gray matter superficially (covered under corresponding lobes)  Cerebral White Matter Myelinated fibers and tracts Communication between cerebral areas, and between cortex and lower CNS – Association tracts—horizontal; connect different parts of same hemisphere – Commissural tracts—horizontal; connect gray matter of two hemispheres – Projection tracts—vertical; connect hemispheres with lower brain or spinal cord  Cerebral White Matter Myelinated fibers and tracts Communication between cerebral areas, and between cortex and lower CNS – Association tracts—horizontal; connect different parts of same hemisphere – Commissural tracts—horizontal; connect gray matter of two hemispheres – Projection tracts—vertical; connect hemispheres with lower brain or spinal cord Association fibers Gray Commissural fibers matter Corpus callosum Projection fibers Corona radiata Internal capsule Parasagittal section and dissection  Basal Nuclei Masses of gray matter deep in white matter Corpus striatum – Caudate nucleus – Putamen – Globus pallidus  Functions of Basal Nuclei Associated with subthalamic nuclei (diencephalon) and substantia nigra (midbrain) Functions thought to be – Influence muscle movements Regulate intensity of slow movements Inhibit antagonistic/unnecessary movements – Role in cognition and emotion  Limbic System Includes the amygdala, hippocampus, and cingulate gyrus Nuclei – Hypothalamic, thalamic, basal Frontal lobe Emotion and memory (learning) – Reacts emotionally to what we are aware of – Consciously aware of our emotions – Interpret emotions of others – Responsible for psychosomatic illness 23  Lobes of the Cerebrum Hemispheres subdivided by deep sulci or fissures Divided into 5 lobes 4 on the surface 1 Deep Frontal Parietal Temporal Occipital Insula  The Cerebrum – Frontal Lobe Rostral to central sulcus Voluntary motor functions Higher intellectual functions – motivation, foresight, planning, memory Verbal communication Personality mood, emotion, social judgment, aggression Primary motor (somatic) cortex is in the precentral gyrus Primary Motor Cortex Precentral Gyrus Motor homunculus  The Cerebrum – Parietal Lobes Between central sulcus and parieto-occipital sulcus Primary site for receiving and interpreting signals of the general senses Primary somatosensory cortex is in the postcentral gyrus Primary Somatosensory Cortex Postcentral Gyrus Sensory homunculus  Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Cerebrum – Occipital Lobe Caudal to parieto-occipital sulcus Principal visual center of the brain – Perceive visual stimuli – Eye movement (frontal eye field) – Correlating images with previous experiences  Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Cerebrum – Temporal Lobe Lateral sulcus Auditory centers – Hearing Smell centers Learning, memory, and some aspects of vision and emotion  Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Cerebrum – Insula Small mass of cortex deep in the brain Made visible only by retracting or cutting away some of the overlying cerebrum Taste, pain perception, hearing, visceral sensation, emotional response  Special Senses Vision Equilibrium Occipital lobe Cerebellum Primary visual cortex Taste Visual association area Parietal lobe and insula Hearing Primary gustatory cortex Temporal lobe and insula Smell Primary auditory cortex Temporal Auditory association area Primary olfactory cortex  Special Senses Language – Wernicke area Recognition of spoken and written language Formulates phrases and transmits a plan of speech Left temporal lobe – Broca area Motor program for the muscles of speech Frontal lobe Diencephalon Thalamus Epithalamus Hypothalamus  Diencephalon - Thalamus 4/5 of the diencephalon Gateway to cerebral cortex Sorts, edits, and relays ascending input – Impulses from cerebellum and basal nuclei to help direct motor cortices – Impulses for memory, sensory integration, regulation of emotion (limbic system) Mediates sensation, motor activities, cortical arousal, learning, and memory  Diencephalon - Hypothalamus Mammillary bodies Pituitary gland – Infundibulum Major control center – Autonomic nervous system and endocrine system Homeostatic regulation of nearly all organs of the body – Hormone secretion – Memory – Thermoregulation – Food and water intake – Sleep and circadian rhythms Emotional responses – Anger, aggression, fear, pleasure,  Diencephalon - Epithalamus Consists mainly of the pineal gland – An endocrine gland – Melatonin Habenula Thin roof over the third ventricle  Brainstem Midbrain Pons Medulla oblongata  Brainstem - Midbrain Short segment – Connects hindbrain and forebrain Contains cerebral aquaduct Corpora quadrigemina – Superior colliculi (function in visual attention) – Inferior colliculi (receive and process auditory input and relay to the thalamus) Cerebral peduncles – Substantia nigra  Brainstem - Pons Anterior bulge in the brainstem – Between midbrain and medulla oblongata 4 cranial nerves originate here Contains parts of the reticular formation – Sleep, respiration, and posture – (reticular formation does so much more!)  Brainstem - Medulla Oblongata Foramen magnum up 3 cm All nerve fibers that travel between the brain and spinal cord Pyramid – Pyramidal decussation of motor signals from cerebral cortex – Contralateral control Medulla Oblongata, Pons, Midbrain Reticular formation – loose network of nuclei Other centers regulate: extending throughout – Vomiting brainstem – Hiccupping Cardiovascular center – Swallowing – Cardiac center adjusts force – Coughing and rate of heart contraction – Sneezing – Vasomotor center adjusts blood vessel diameter for blood pressure regulation Respiratory centers – Generate respiratory rhythm – Control rate and depth of breathing  Cerebellum Cerebellar hemispheres Vermis Folia (gyri) Arbor vitae Coordinate skeletal muscle contractions – receives impulses from cerebral cortex of intent to initiate voluntary muscle contraction – calculates the best way to smoothly coordinate muscle contraction Several sensory, linguistic, emotional, and other non-motor functions