Give a brief account of the structure and functions of the brain of man.

Brain is the site of information processing and control.

• It is protected in the cranial cavity and covered by 3 cranial meninges.
• They are outer duramater, middle arachnoid membrane and inner piamater.
• Sub arachnoid space is filled with cerebro spinal fluid (CSF).
• It is divided into 3 parts:
  i) Fore brain
  ii) Mid brain
  iii) Hind brain

1. FORE BRAIN: It consists of 

i) Olfactory bulbs concerned with smell.

ii) Cerebrum: 

• It forms a major part of the brain. It is divided into 2 hemispheres and are joined by corpus callosum.
• Outer portion is cerebral cortex that shows gyri and sulci and inner cerebral medulla.
• Each hemisphere consists of 4 lobes namely frontal, parietal, temporal and occipital lobes.
• Cerebral cortex contains 3 functional areas - Sensory area, motor area and association areas (memory and communications).

iii) Diencephalon: 

• It contains 3 parts: epithalamus, thalamus and hypothalamus.
• Epithalamus has anterior choroid plexus and pineal gland.
• Hypothalamus has pituitary gland. It controls and integrates the activities of the ANS.
   

2. MID BRAIN: It consists of cerebral peduncles and 4 optic lobes called corpora quadrigemina. Superior colliculi are visual function while inferior colliculi are auditory in function.
 

3. HIND BRAIN: It comprises of cerebellum, pons Varolii and medulla oblongata.

• Cerebellum is the 2nd largest part of the brain. It consists of 2 cerebellar hemispheres and a central vermis. It has a branching tree like white matter called arbor vitae. It is the gyroscope of the body.
• Pons Varolii: It forms bridge between 2 cerebellar hemispheres and has pneumotaxic centre.
• Medulla Oblongata: It is the posterior part of brain and continuous with spinal cord below. It has posterior choroid plexus which secretes CSF into cavities of brain. It has cardiovascular and respiratory centres.
• The midbrain, pons and medulla oblongata are collectively referred to as brain stem.