Q.Which part of our brain occupies major area in the cranial cavity? Explain its functioning mechanism.

The cerebrum, the largest part of the brain filling most of the cranial cavity, is the centre of voluntary action, sensation, intelligence, memory, thought, speech and emotions.

The human brain is the master control organ, lodged and protected within the cranial cavity of the skull. It has three main regions — the forebrain, midbrain and hindbrain. Of all its parts, the cerebrum (part of the forebrain) is by far the largest and occupies the major area of the cranial cavity.

Structure of the cerebrum (in brief):

• It is divided by a deep longitudinal fissure into two halves, the right and left cerebral hemispheres, connected internally by a band of nerve fibres called the corpus callosum.
• Its outer surface, the cerebral cortex, is grey matter thrown into folds (gyri) and grooves (sulci) that greatly increase its surface area; beneath lies the white matter.
• Each hemisphere is marked into lobes — frontal, parietal, temporal and occipital.
• The cortex has three kinds of functional areas: sensory areas (receive sensations), motor areas (control voluntary movement) and association areas (integrate information for higher mental activity).

Functioning mechanism / functions of the cerebrum:

1. Control of voluntary actions: the motor areas of the cortex initiate and control the voluntary movements of skeletal muscles (walking, writing, speaking). Interestingly, each hemisphere controls the opposite side of the body (the left cerebrum controls the right side and vice versa).
2. Reception and interpretation of sensations: the sensory areas receive impulses from the sense organs and skin, so the cerebrum perceives and interprets touch, pressure, pain, temperature, sight, hearing, taste and smell.
3. Centre of intelligence and higher mental faculties: the association areas are responsible for intelligence, reasoning, thinking, judgement, learning, memory and imagination.
4. Seat of will, emotions and personality: it governs willpower, emotions (through links with the limbic system) and the personality of the individual. …