Disorders of the nervous system

Abstract

The highest centres of the brain, both anatomically and in terms of the special intellectual functions that distinguish man from the lower animals, are contained in the cerebrum with its left and right hemispheres. These consist of a cortex of grey matter containing the nerve cells or neurones, and the deeper white matter containing the nerve fibres. There are special areas of the cortex concerned with different functions — thus the motor area which governs control of movements, is anterior to the central sulcus or fissure, the sensory area is posterior to it. In general, the left hemisphere is responsible for the right side of the body and vice versa, due to a crossing of the nerve tracts to the opposite side lower in the brain or spinal cord. The speech centre is in the left side of the brain in right-handed people and in most left-handed people, lying below the motor area. Hearing is appreciated in the temporal lobe. Thought processes are dependent on an intact speech and language mechanism — we think in terms of specch. Vision is appreciated in the occipital lobes posteriorly. The function of a large part of the frontal lobe is uncertain, but it may be responsible for behaviour and personality traits.