HUMAN BRAIN (ENCEPHALON)

The human brain is well protected in the bony box called as cranium of the skull. It is soft, whitish, large-sized and slightly flattened. The weight brain is about 1300-1400 grams in weight and 1300-1500 cc in volume. The brain develops up to six years of age and it contains 30,000 million neurons. It can be divided into different parts as follows:

1 forebrain - It is also called as Prosencephalon. It is still divided into three main parts, Olfactory lobes Cerebrum and Diencephalon.

a. Olfactory lobes - These are paired small, solid bodies present ventrally in the forebrain. They are only covered from ventral side. Also they have olfactory bulbs and olfactory tracts.

b. Cerebrum - These are also called as telencephalon. It is the most prominent and the largest part of forebrain. It makes 80-85 % of the weight of the brain. It again divides into two cerebral hemispheres by a median longitudinal fissure. Both cerebral hemispheres are interconnected by a thick band of transverse nerve fibres called as corpus callosum.

c. Diencephalon - These are also called as Thalamencephalon. It is present below the corpus callosum and above the midbrain. It is covered by cerebral hemisphere It encloses a third cavity termed as ventricle (diocoel) which communicates with lateral ventricle through a narrow opening is known as foramen of Monro.

2. Midbrain - It is the middle part of the brain and is present between diencephalon and pons varolii. A narrow passage called as Iter. It again divides into two parts:

a. Corpora quadrigemina - It is present in dorsal thick wall of midbrain. Upper pair called as superior colliculi receives impulses from optic nerves. These colliculi controls and coordinate movement of heat in response to visual stimulus.

b. Crura cerebri - It is a pair of thick bands of longitudinal nerve fibres. These fibres connect cerebrum, cerebellum and spinal cord and also functions as relay function. It is also known as RAS network.

3. Hindbrain - It is present on the posterior side of the brain. It again divides into three parts cerebellum, Pons varolii and Medulla oblongata.

Cerebellum - It is the second most largest region of brain and is well develop in man. It weighs is about 11 %. It is made up of two lateral cerebellar, hemispheres and one median vermis. It has outer grey matter and inner white matter. Outer grey matter is called as cerebellar cortex also shows folds and gyri and sulci like cerebrum. The inner white matter is cerebellar medulla which sends branching tree like processes in grey cortex called as Arbor vitae.

b. Pons Varolii - It is present below cerebrum and in front of cerebellum above the medulla oblongata.It contains mainly the nerve fibres which forms bridges between cerebrum and medulla oblongata.

c. Medulla oblongata - It is the most posterior part of the brain which continues as a spinal cord. Medulla has inner grey matter and outer white matter. About 8 pairs of cranial nerves are arises form medulla. Medulla controls all the involuntary functions like heart beats, blood circulation, respiration and peristalsis

These are the some description of brain and it's parts
Follow me as @sanks7