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.