Structure of Brain:
The human brain is divisible into 3 parts –
1. Forebrain
2. Cerebellum
3. Brain stem
1. Forebrain:
In human beings, the forebrain includes two parts –
1. Cerebral hemispheres or cerebrum
2. Diencephalon
2. Cerebrum:
- It forms 2/3 part of the brain and a longitudinal fissure divides it into two hemispheres.
- Both the hemispheres remain connected internally by the corpus callosum.
- Each cerebral hemisphere consists of five lobes –
1. Frontal lobe
2.Parietal lobe
3. Temporal lobe
4. Occipital lobe
5. Insula lobe
- The insula lobe is not visible externally.
- The frontal lobe is the largest. A central sulcus separates the frontal and parental lobes which are also called as the fissure of Ronaldo. Similarly, a lateral cerebral fissure separates the frontal and the temporal labels which are also called as the fissure of Sylvius.
- The parental and the occipital lobes remain separated by a parieto-occipital fissure. The outer 2 to 4 mm thick part of the cerebrum is called cortex or grey matter. It consists of 10% of the total neurons of the brain. The cortex exhibits distinct gyri (ridges) and sulci (furrows).
- These gyri and sulci increase the surface area of the cortex by 3-times. The inner mass of the cerebrum is called as white matter.
Functions of the cerebrum:
1. Frontal lobes: They control memory, reasoning, thinking, determination, emotions, judgment, planning, experience, concentration, will power and personality. They also control voluntary muscles and interpret many sensations.
2. Parietal lobes: They interpret sensory perception of touch, pain, cold, heat etc. They also control speech and handicraft. They also associated with the understanding of the thoughts.
3. Temporal lobes: They interpret and decode sound. In addition to language comprehension, they also interpret smell and auditory sensations.
4. Occipital lobes: The interpret and decode visual sensations particularly sensations concern with colours and shapes. They also control eye movements.
5. Insula lobes: They coordinate memory and other parts of the cerebrum.
2. MidBrain: It is the middle part of the brain and also called as mesencephalon. It consists of two parts –
1. Corpora Quadri-gamine:
- It includes four optic lobes which are collectively called as Corpora Qudrigemina.
- Out of 4 lobes, two lobes are superior optic lobes and two are inferior optic lobes.
- The optic lobes remain joined to the dorsal surface of the midbrain with the help of Tatum.
- The optic lobes receive stimuli related to vision & hearing.
2. Cerebral peduncle:
- It is also called as Crura Cerebri.
3. HindBrain:
- It is posterior or terminal part of the brain.
- It consists of three parts:
1. Cerebellum
2.Pons Varolli
3. Medulla Oblongata
