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1、Nervous System,Dept. of Anatomy Zhou Hong Ying,Introduction and overview,Introduction and overview,Division of nervous system Organization of central nervous systemTerm of central nervous system(Development of CNS),Peripheral nervous system:31 pairs of spinal nerves 12 pairs of cranial nervesAutonom
2、ic nervous fibersganglia,The human nervous system,Central nervous system :-Spinal cord & brainBrain stem medulla pons midbrainDiencephalonsCerebellumCerebral hemisphere,The human nervous system,The brain occupied the cranial cavityThe spinal cord located in spinal canal,The cranial nerves attached t
3、o the brainThe spinal nerves attached to spinal cord,Components and organisation of the nervous system,The basic structural and functional unit of the nervous system is the nerve cell or neuron.,Neuron,Basic structure:BodyDendrites a axonAxons may be highly branched=collaterals,Types of neurons,by f
4、unction: Afferent neuron/sensory neuron Efferent neuron/motor neuron Interneurons / relay neurons,Types of neurons,by structure : multipolar neuron bipolar neuron unipolar neuron (pseudounipolar),The nervous system is made up of millions, perhaps billions, of neurons.,Information is passed between n
5、eurones at specialised regions called synapses.,Synapse,Synapse is the junction between two neurons where the electrical activity in one neuron influences the excitability of the second neuron. At this point (the synapse), Chemical and Electrical reaction occurs.,Chemical synapses,neurons neuroglia.
6、,Terms of NS,Grey matter some regions in the CNS are relatively enriched in nerve cell bodies White matter some regions in CNS are relatively enriched in processes (usually axons) Ganglia some regions in the PNS are relatively enriched in nerve cell bodies Nerve cell bodies in the CNS with similar a
7、natomical connection and function are called nuclei,Terms of NSnerve,Nerve the processes (usually axons) in the PNS often myelinated formed by nerve fibers of neurons: including the AXONS and their glial envelopes (myelin sheath),Terms of NS,Tracts that nerve processes sharing common connections and
8、 functions tend to follow same course are called running in pathways or tractAfferent tracts are called ascending tract or affect (sensory ascending tract or pathway )Efferent tracts are called descending tract or effect (motor descending tract or pathway ),Terms of NS -Decussation,pathway conveying
9、 sensory(or motor) information to a conscious level (or motor area) crossover, or decussate the median plane , from one side to the other are called Decussation.In general, each cerebral hemisphere perceives sensations from, and controls the movements of , the contralateral side of the body.,Decussa
10、tion,Decussate partly,optic NChiasma Optic tract,Summary,Definitions of NS neuron (axon, dendrite, cell body) grey matter, nuclei, ganglion white matter, tract , (pathway) decussation,Overview of CNS,Brain & Spinal Cord,callosum,cerebellum,MedullaPonsmidbrain,hemispheres diencephalonthalamus hypotha
11、lamus,Median sagittal section of brain showing the principal subdivision and some important landmarks in brain,Telencephalon,Diencephalon,Brain stem,cerebellum,spinal cord & spinal nerves,2 enlargements conus medullaris terminal filum cauda equina,Spinal cord,Transverse sections of spinal cord,Spina
12、l cord: external features,Spinal cord: external features,Nerves connected to spinal cord:Dorsal & ventral rootsDorsal & ventral ramiStructures of spinal cordSulcus: ventral median fissure, dorsal medianGray matter: anterior horn, posterior horn, lateral horns, commissureCentral canal,Spinal nerves,A
13、nterior root is motor Posterior root is sensory Anterior and posterior roots united to form spinal nerve at the IV foramen. Spinal nerve divides into anterior and posterior rami,Each of the 31 pairs of spinal nerves is mixed nerve,Somatic motor,Autonomic motor,Ventricular system,Ventricular system,Ventricular system,Development of CNS,
