Royal Army Medical Corps training pamphlet / War Office.

Date:
1944
Catalogue details

Licence: Public Domain Mark

Credit: Royal Army Medical Corps training pamphlet / War Office. Source: Wellcome Collection.

    63/376 (page 51)
    CHAPTER 10 THE NERVOUS SYSTEM 73. The nervous system controls all the movements of the body. It consists of (a) nefve centres, (b) nerve cords, and (c) nerve-endings. The nervous system has two parts :— The cerebrospinal (or central) nervous system, controlling voluntary movements—e.g. of limbs. The autonomic (or sympathetic) nervous system, con- trolling involuntary movements—e.g. of heart and intestines. The cerebrospinal system comprises .brain, spinal cord and nerves, while the autonomic system works through small nerve centres called ganglia. 74. The brain.—The brain is the great nerve centre of the body, and is contained in and protected by the skull. It is enclosed in three distinct membranes or skins: an outer known as the dura mater ; a middle called the arachnoid ; and an inner called the pia mater. These membranes continue downwards over the spinal cord. Between the inner mem- brane, which covers the brain and cord, and the middle or arachnoid membrane, is a space containing the cerebrospinal fiuid (Fig. 28). This colourless fluid bathes and protects the brain and cord and also fills the cavities (ventricles) inside the brain. Itis continually changed, being formed in the ventricles and absorbed by large veins in the membrane lining the skull. The brain receives messages from nerve-endings, or outposts, in the eyes, ears, nose, skin, muscles, etc., and issues orders to the muscles to make them move in any desired way. It con- sists of countless nerve cells and nerve fibres. The chief parts of the brain are the cerebrum, the cerebellum, and the brain-stem (Fig. 28). The cerebrum lies uppermost in the skull and consists of two halves which look alike. The outer surface of the brain is covered with rounded ridges and furrows, and is plentifully supplied with blood-vessels which run into these furrows; but the main blood-supply of the brain passes into its base.