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Lecture

Nervous System notes.docx

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Department
Kinesiology & Health Science
Course Code
KINE 2031
Professor
Neil Smith

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Nervous System 11/24/2012 8:08:00 PM Function: 1. Sensory Input: detects internal & external changes 2. Integration: processes sensory info and decides on a response 3. Motor Output: if response required, NS sends message to respond Organization: Central Nervous System: o Brain & spinal cord o Neurons: sensory, motor, interneuron Peripheral Nervous System: o Sensory (afferent):  Receives info from receptors and transmits info to CNS  Subdivided into: o Sensory Somatic o Visceral – generally aren’t conscious; exceptions are present o Motor (efferent):  Transmits motor impulses from CNS to muscles or glands  Subdivided: o Somatic – voluntary o Visceral motor (autonomic)  Parasympathetic  Sympathetic Neuron structure: o Cell body o Dendrites: extension of cytoplasm; direct info towards cell body o Axon: extension of cytoplasm; direct info away from cell body Cells in CNS o Astrocyte:  blood brain barrier  between capillary and neuron  regulate what substances come into contact with the neuron  act like glue o Oligodentrocyte:  Produce myelin around axons o Micoglial:  Destroy viruses and bacteria o Ependymal:  Lines ventricles of the brain  Along with choroid plexi form CSF Cells in PSN o Schwann:  Forms myelin around axons o Satellite:  Surround and separate cell bodies in ganglia  Regulate exchange of nutrients & wastes between neuron and their environment The Brain: Forebrain o Cerebrum  2 hemispheres  cortex – outer covering; non myelinated, convoluted  sulci – grooves o Longitudinal fissure: groove separating the hemispheres o Central Sulcus: separates frontal lobe from parietal o Lateral sulcus: superiod border of temporal lobe o Parieto-occipital sulcus: separates parietal and occipital  gyri – valleys o Pre-central gyrus: directly in front of central sulcus  Motor in function o Post-central gyrus: behind central sulcus  Sensory  Insula lobe is deep to the temporal lobe  White matter tracts: join gyri in different hemispheres o Commisural tracts: join left and right hemisphere; ex. Corpus Collosum o Projection tracts: transmit sensory info up to cortex or motor axons that transmit info down through cerebrum  Association Tracts: join gyri in same hemisphere o Arculate fibers: connect gyri within the same lobe o Longitudinal/fasciculi fibers: connect different lobes within same hemisphere o Thalamus:  Major relay center for all sensory info going into cerebral cortex o Hypothalamus  Controller for autonomic NS (motor visceral) & endocrine system o Basal Ganglia  Receive info from cerebral cortex to regulate skeletal movement Midbrain: o Functions:  Eye movement  Visual & auditory reflex center o Superior Cerebellar Peduncles: motor signals from cerebellum to midbrain o Cerebral peduncle: connects midbrain to forebrain & cerebrum Hindbrain o Pons  Contains nuclei of canial nerves 5-7 and parts of 8  Regulates breathing  Middle Cerebellar Peduncles: brings motor signals from cerebellum to pons o Medulla Oblongata  Nuclei for cranial nerves 8-12  Regulates cardiac, respiratory, blood pressure  Inferior Cerebellar Peduncle: bring motor signals from cerebellum to medulla Cerebellum o 2 hemispheres o vermis: narrow band of cortex separating the hemispheres o coordinates motor movement o Arbor vitae: myelinated axons that resemble a tree Meninges o Dura Mater  Fold located in longitudinal fissure  2 layers in brain, 1 in spinal cord  Falx cerebri: splits cerebral hemispheres  Falx cerebelli: verical fold between lobes of cerebellum  Tentorium Cerebelli: horizontal fold between cerebellum and occipital  Diaphragma Sallae: roof dura over sella turcica  On the brain the dura can split and join back together; when they split it creates: o Venous Sinuses  Superior Saggital Sinus: top edge of falx cerebri  Inferior saggital sinus: bottom edge of falx cerebri  Straight sinus: inferior sinus continues post. to this sinus  Occipital sinus: in the falx cerebelli  * all meet at the confluence of sinuses  Right & Left Transverse Sinuses: outer edge of tentorium cerebelli  Sigmoid Sinus: transverse continues anteriorly to this sinus  Sigmoid sinus then turns inferiorly and exits the cranial cavity as the right and left internal jugular veins  Inferior saggital straight occipital confluencetransversesigmoid internal jugular vein  For superior it does not go to straight sinus; rest is the same  Right and Left Cavernous Sinuses: found in diaphragma sellae  Right and Left Inferior and Superior Petrosal Sinuses: drain back to sigmoid sinus  Cavernous petrosal  sigmoid  internal jugular vein o Dural partition/folds – membranous layers that divide parts of the brain o Arachnoid Mater  Connected to pia mater by strands called trabeculae  Space between arachnoid and pia is the subarachnoid space (CSF flows here)  Arachnoid granulations/villi are extensions unto superior saggital sinuses o These areas are extremely permeable; clear out waste and old CSF o Pia Mater  Delicate inner meningeal layer  Sits right on the brain and spinal cord Ventricles of the Brain: o Right and Left ventricles  Located in cerebrum rd  Communicate with 3 ventricle via the interventricular foramina o 3 Ventricle  Located between the two thalami  Continues down to the midbrain as the cerebral aqueduct which then continues in the pons o 4 ventricle  cerebral aqueduct continues in the pons region as the 4 th  it continues as the central canal in the spinal cord  there are 3 apertures/openings that allow for communication of the ventricles with the subarachnoid space Cerebral Spinal Fluid o CSF= plasma + fluid from ependymal cells o Formed by choroid plexi  Made up of capillary network on the roof of the ventricles with ependymal cells  Blood plasma is filtered through ependymal cells and trapped in ventricles (now called CSF)  CSF can exit ventricles through the apertures and flow through the subarachnoid space o Functions:  Protect the brain  Buoyancy for the brain  Diagnostic tool for health of the nervous system Spinal Cord o Outer surface of the cord has 2 depressions: anterior & posterior median fissures o Conus medullaris: bottom of the cord at the level of the 2 limbar vertebrae; end of solid spinal cord before it turns into cauda equnia o covered by same 3 meningeal layers o Filum terminale: continuation of pia mater from conus medullaris to the sacrum/coccyx  Anchors spinal cord to coccyx o Central canal of the cord is the continuation in the spinal cord of the 4 ventricle o *generally sensory comes in through the back and motor leaves through the front o Gray matter: located centrally  Posterior (dorsal) horn: contains axons of sensory neurons (somatic afferent & visceral sympathetic afferent); brings sensory info into posterior of spinal cord  Anterior (ventral) horn
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