The Human Brain Anatomy is a quite important topic for biology class 12 .Brain is a vital and delicate organ of the human body so it is protected inside the skull(cranium). Its average weight is about 1200 to 1400 grams. It consists of about 10,000 million neurons.
It has 3 main parts. These are-
1.Fore brain
2.Mid brain
3.Hind brain
(Shown below is the human brain diagram)
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| The Human Brain Diagram |
1.Fore brain - This is the biggest part of the human brain. It further consists of three main parts.
(a) Olfactory Lobes - There are two very tiny club-shaped lobes which can be seen only on the ventral side of the brain. Each of them consists of two parts-
*Olfactory Bulb
*Olfactory Tract
(b) Cerebrum - This is the largest part of the brain. The cerebral hemispheres are connected to each other by corpus collasum which consists of about 200 million nerve fibres. The outer surface of cerebrum is called cerebral cortex and consists of gyri ( upward folds) and sulci (downward grooves) .Cerebral cortex is made up of grey matter.Each cerebral hemisphere is divided into four parts or lobes. These are-
*Frontal lobe
*Parietal lobe
* Occipital lobe
* Temporal lobe
The right part of the brain controls the left part of the body and vice-versa.Most of the activities take place in the cerebral cortex.
2.Mid brain - It consists of several groups of nuclei that are dispersed in white matter. It has two parts-
(a) Corpora Quadrigemina - These are two pairs of rounded projections present on the upper surface of the mid brain in which one pair is known as the superior colliculi and the second is known as the inferior colliculi . A pair of superior and inferior colliculi present on either side is called corpora bigemina.
(b) Cerebral Peduncles - These serve the purpose of joining the mid brain and the hind brain. They occur as two bundles of nerves and are found on the lower surface of the mid brain.
3.Hind brain - It has two parts-
(a) Cerebellum - Its surface is made up of cerebral cortex of grey matter while its medulla is made up of white matter with nuclei made up grey matter dispersed in it .It has the following parts-
*Cerebellar Hemispheres
*Vermis
It consists of purkinje cells in its middle layer. Like that of the cerebrum, three paired lemulles called peduncles join the cerebellum with the other parts of the brain. These are-
*Superior Cerebellar Peduncles - They connect it with mid brain.
* Middle Cerebellar Peduncles - They serve to communicate with the pons.
*Inferior Cerebellar Peduncles - They connect it with the medulla oblongata and the spinal cord.
(b) Brain Stem - It has two parts-
*Pons Varolii - It is found above the medulla oblongata and helps in controlling some aspects of respiration.
*Medulla Oblongata - It is connected above with the pons varolii and below with the spinal cord. It has a cavity called the fourth ventricle with a roof called posterior choroid plexus. There are three openings present below the roof. These are-
*two lateral apertures
*one median aperture
These apertures allow the cerebrospinal fluid in the spaces that surround the brain.
Hope you found this topic of The Human Brain Anatomy for notes of biology class 12 to be quite useful.You can also practice this topic using Worksheets for Science related to this topic.
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