Brain (Study - Encephology) || Brain Encephology || BRAIN IS DIVIDED INTO THREE PARTS WITH THE SUB DIVISIONS||

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                               Brain


                (Study - Encephology)

# Brain is the highly specalised organ of the body. Brain develops by the enlargement of embryonic neural tube... It is presemt in the cranial cavity of the skull and forms about 98% of the central nervous system..

# Brain is protected by connective tissue membrane called MENINGES..

# In fishes, only one protective covering is present called MENINX PRIMITIVA..

# In amphibians, reptiles, birds, brain is covered by two meninges: Inner- pia arachnoid and Outer - Duramater..

# In mammals three protective covering is present: Inner - piamater ; Middle - arachnoid and Outer - durameter...

 # Just below and above the arachnoid membrane space is present, called SUBARACHNOID and SUBDURAL respectively.. 

These space are filled with Cerebrospinal fluid protect the brain from mechanical injury while cerebrospinal fluid protect the brain from Mechanical shock and also helps in exchange of nutrients, gases and wastes, between the nervous tissue and blood.. 

  

   BRAIN IS DIVIDED INTO THREE PARTS WITH THE SUBDIVISIONS. 


    (1) Forebrain/ Prosencephalon 

    (2) Mid brain/ mesocephalon 

    (3) Hindbrain/ Rhombencephalon


Brain is formed of two types of matter - gray matter ( cyton, non medullated) and white matter ( medullated nerve fibre)..

 [NOTE]-- In medulla oblongata and pons varolii, gray matter is internal . 


                 1. FORE BRAIN


» Olfactory Lobes

These are paired, club shaped lobes consisting of olfactory bulb and olfactory track They enclose a cavity, rhinocoel. These lobes ate sensitive to smell.


» Cerebral Hemisphere 

These are largest sized lobes connected together by a band called corpus callosum, They enclose a cavity, paracoel/lateral/ventricles (I st and II nd venticles). The left half of the brain controls the right side of body and vice versa. Roof of the cerebral hemisphere is called pallium. The ventrolateral wall is called corpora striata controls all the voluntary activities of body and are concerned with perception of a number of sensory stimuli, It is a seat of memory, will, intelligence, reasoning, learning etc.


» Diencephalon

Diencephalon consists of epithalamusthalamus and hypothalamus Epithalamus is not formed of nervous tissue. Its anterior part is highly vascular forming anterior choroid plexus which secretes cerebrospinal fluid. Epithalamus also forms pineal body, an endocrine gland. Floor of diencephalon 

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