introduction

د. فرح نبيل عباسطبيبة اختصاص في علم وظائف الجسم و الفسلجة العصبيةدكتوراه في طب الفسلجة العصبية(تخطيط الدماغ-الأعصاب-العضلات)رئيس فرع الفسلجة و الفيزياء الطبية في كلية الطب/جامعة بابلمدير وحدة الفسلجة العصبية في مستشفى مرجان التعليمي عضو الجمعية العراقية لأطباء الفسلجة العصبيةعضو الاتحاد البريطاني للعلوم العصبية/جامعة كامبرجعضو الاتحاد الدولي للفسلجة العصبيةشهادة التدريب في مستشفى الجامعة الأمريكية/بيروت MBChB, MSc, PhD, BNA, Neurophysiology

GENERAL DESIGN

100 billion neuronsIncoming signalsSynaptic connectionsOut put signalsSignal transmission through synapses  forward direction

SENSORY PARTS OF NS

Sensory experience  excites sensory receptors immediate reactionmemory of experienceInformation enters the CNS:Spinal cord at multiple levels, Reticular substances of medulla, pons and mesencephalon.CerebellumThalamusAreas of cerebral cortex

MOTOR PARTS OF NS

Control different body functions Control of skeletal MM from: Spinal cord Reticular substances of medulla, pons and mesncephalon. Basal ganglia Cerebellum Motor cortex

INTEGRATIVE FUNCTION OF NS

Incoming information  NS  processing  mental and motor functions99% of sensory information discarded by the brain:Only the important information excites the mind

Synapses & Information Processing

Junction point Determine the directions of signals. Easy and difficult transmission of signals Synaptic transmission controlled by facilitatory and inhibitory signals from other areas in the NS Postsynaptic respones Synapses perform a selective action



MAJOR LEVELS OF CNS FUNCTION
Spinal cord level (not simple conduit )Lower brain or subcortical level: medulla, pons, and mesencephalon (Control subconscious body activities).Higher brain or cortical levelLarge memory storageWorks in association with lower centersWithout  imprecise function

THE BRAIN

100 billion neural cells Adult brain weighs 1.5 Kgm. Adult brain receives about 20% of the total blood flow to the body/minute.

4 Parts Cerebrum Diencephalon Brain Stem Cerebellum

Embryological Development
The Forebrain (Prosencephalon)Telencephalon  two cerebral hemispheresDiencephalone  thalamus, hypothalamus, and part of the pituitary gland.The midbrain (Mesencephalon)Corpora QuadrigeminaCerebral PeduncleRed nucleusSubstantia Nigra

Embryological Development

The Hindbrain (Rhombencephalon)Metencephalon  pons and cerebellumMyeloencephalon  medulla oblongata

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Parts of the Brain

Cerebral Cortex
The cortex – superficial gray matter; accounts for 40% of the mass of the brainIt enables sensation, communication, memory, understanding, and voluntary movementsEach hemisphere acts contralaterally (controls the opposite side of the body)Hemispheres are not equal in functionNo functional area acts alone; conscious behavior involves the entire cortex

Functional Areas of the Cerebral Cortex

The three types of functional areas are:Motor areas – control voluntary movementSensory areas – conscious awareness of sensationAssociation areas – integrate diverse information

Cerebral White Matter

Consists of deep myelinated fibers bundled into tractsThe tracts are classified according to the direction in which they run:Commissures – connect corresponding gray areas of the two hemispheres allowing them to work as one unitThe largest is the corpus callosumAnterior and posterior commisuresAssociation fibers – connect different parts of the same hemisphereProjection fibers – enter the hemispheres from lower brain or cord centers