STRUCTURE OF BRAIN

Brain is divided in to three parts-

(A)Fore brain       (B) Mid brain    (C)Hind brain

(A)Fore brain or Prosencephalon:-

It is the frontal or anterior part of brain constists three parts-

(a)Cerebrum   (b)Thalamus   (c)Hypothalamus 

(a)Cerebrum:-

-It is the largest part of the brain.
-It is divided in to two halves called cerebral hemisphere.
-Both cerebral hemisphere is connected by corpus callosum.
-Corpus callosum is a long,thickand curved band of myelinated nerve fibre.
-Left hemisphere control right side and right hemisphere control left side.
-Surface of cerebrum is highly folded.
-The upper layer of cerebrum is known as cerebrum cortex made up of grey matter which control muscle movement and also involve in hearing,vision,memory,sensation and communications.
-Inner part of cerebrum is known as cerebrum medulla which is made up of mylinated nerve fibre and appears white.

(b)Thalamus:-

-It is the lateral part of diencephalon formed of mostly gray matter.
-Cerebrum extend around thalamus.
-Major function of thalamus to cordinate moter and sensory signals so also called relay station.

(c)Hypothalamus:-

-It is the floor of diencephalon where gray matter are scattered in white matter.
-It is very importent part of brain.
-It controls body temperature,appetite centre(urge for eating),osmoregulation,sweating,sleep,respiration,heart beat etc.
-Neurosecretory cells of hypothalamus secrete hypothalamic hormone also callrd super ,aster gland.

(B)Mid brain:-

-It is also called mesencephalon.
-It is small part of brain present between hypothalamus of the fore brain and pons of the hind brain.
-In this part nervr cells are scattered in white matter.
-A narrow canal passes through mid brain called cerebral aqueduct.
-Main function of mid brain is control to auditary reflex and visual reflex(movement of eye ball and head to focus on an object).
-Mid brain and hind brain form brain stem. 

(C)Hind brain:-

-It is also called rhomboencephalon.
-It is composed of three component.

1. Cerebellum    2.Medulla oblongata       3.Pons varolli

1.Cerebellum:-

-It lies behind the cerebrum.
-It is highly developed in bipedal mammals.
-It surface is highly convoluted to provide extra space for neurons.
-It controls body balance,rapid muscular activity such as cycling,running,typing etc.

2.Medulla oblongata:-

-It is the posterior part of hind brain which gradually tapers to form spinal cord.
-It controls respiration,cardiovascular reflex,gastric secretion and has reflex centre fore vomiting,sneezing,salivation etc.

3.Pons varolli:-

-Its nerve fibre connects cerebrum,cerebellum,medulla and spinal cord.


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