الثلاثاء، 25 يوليو 2017

General topography of nervous system

General Topography of Nervous System 





Divisions of Nervous System :
1. Central Nervous System (CNS) :
Include :
 Brain (right and left hemispheres
 spinal Cord (C, T, L, S, Co)
2. Peripheral Nervous System (PNS)  :
 Nerves and receptors 
 Plexuses and ganglia 
3. Autonomic nervous system (ANS) :
Sympathetic 

 parasympathetic systems 
4. Enteric nervous system 
5. Conducting system of the heart

 Microscopic topography of CNS  
 Cell bodies = gray matter 
Cortex
Nuclei 
 Centers

Structures 
 Processes 
Tracts 

 Bundles   
 Types of fibers in the CNS :
1. Association 
2. Commissural fibers 
3. Projection 

 Microscopic topography in PNS 

Cell bodies 
 Ganglia 
 Processes 
 Nerves 
Trunks
Plexus 
 Central Nervous System 

 Intracranial part called brain
 Vertebral part called spinal cord .
Brain 
 Human brain starts functioning at 42 end day of IUL(intrauterine life)

Weight at birth 400gms, triple during 3yrs, maximum wt 1400gm reached at 18 yrs, after 50 yrs starts to decline to reach about 1100 gms. Wt range between 1100 to 1700 gm.
 Females lighter than males.
Topography of brain 
 Rapid proliferation of cells in limited area
Enfolding of external layer giving sulci & gyri.
Some cells burried within brain substances give deep nuclei of brain.
Functional Lobes
Frontal lobe deals with motor, thinking & idea formation, personality, insight and foresight, (higher functions).
Parietal lobe deals with sensation, language, orientation and perception.
 Occipital lobe deals with primary vision and visual association. 

 Diencephalon  composed of thalamus, epithalamus, hypothalamus and subthalamus
 Brain stem composed of midbrain, pons and medulla oblongata.
Deals with vital centers control, cranial nerves, subconciousness emotion and olfaction, memory and learning.
 Cerebellum: It is the structure of co-ordination and equilibrium. 
 Regulation of voluntary as well as involuntary movements.
 Role in learning and motor memory
 Spinal Cord

 Located in vertebral column.
Conduit functions i.e. conduction of informations from brain to target organs and vise versa.

Control of local reflexes.
 Autonomic Nervous System :
 Concerned with control of visceral activities i.e. CVS, RS, GIT, reproductive and glands
Composed of sympathetic and parasympathetic systems.

 Sympathetic is the system of stressful conditions while parasympathetic system is active during rest.





About Mohammed Abd Alkariem Ahmed

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