Jade Whytell A06- Functions and Dysfunction of the nervous system 17/04/2013
The Brain- The brain, when fully developed, is a large organ which fulls the cranial cavity. Early in its development the brain becomes divided into three parts known as the forebrain, midbrain and hindbrain. The forebrain is the largest part and comprises the cerebrum, it is divided into right and left hemispheres by a deep longitudinal fissure. The separation is complete at the front and the back but in the centre the hempispheres are joined by a broad band of nerve fibres called the corpus callosum. the outer layer of the cerebrum is called the cerebral cortex, and is composed of grey matter thrown into numerous folds or convolutions called gyri, separated by fissures called sulci. This enables the surface area of the brain, and therefore the number of cell bodies, to be greatly increased. The general pattern of the gyri and sulci is the same in all humans; three main sulci divide each hemisphere into four lobes, each named after the skull bone under which it lies. The central sulcas runs downwards and forwards from the top of the hemisphere to a joint just above the lateral sulcas; the lateral sulcus runs backwards from the lower part of the front of the brain and the parieto-occipital sulcas runs downwards and forwarss for a short way fron the upper posterior part of the hemisphere. The lobes of the hemispheres are the frontal lobe, lying in front of the central sulcus and above the lateral sulcus, the parietal lobe lying between the central sulcas and the parieto-occipital sulcas and above the line of the lateral sulcas; the occipital lobe, which forms the back of the hemisphere and the temporal lobe lying below the lateral sulcus and extending back to the occipital lobe. The area lying immediately in front of the central sulcus is known as the pre-central gyrus and is the motor area from which arise many of the motor fibres if the central nervous system....
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