BOW-LEGS or BANDY LEGS.—Legs which are bent in an outward curve (see Fig. 99). They are the result of a curvature of the bones of the thighs and lower legs, usually due to rickets. In very small children, bow legs may straighten if the cause of the condition (rickets) is treated. In older children, one cannot with certainty count upon straight growth ; and splints must be used to act upon the deformity. Operation, consisting in breaking or chiselling of the curved bones, is necessary only in the most severe cases.
BRAIN.—The chief mass of nervous tissue in the body. In it are con nected all of the nervous fibres from the different parts of the body, and it serves as the chief organ whereby the different parts of the body arc co ordinated one with another ; more particularly it has the important function of fitting man to his environment, through the intellectual processes. The brain is an extremely complex organ. It may he likened very crudely, and in a rough mechanical way, to a telephone switchboard. It is the " Central " for all forms of activity within the body, as well as those in the outside world that may be brought in contact with the body. Through the brain all messages from the outside are received, and from it are issued all impulses to perform the different acts that constitute man's conduct.
The sense-organs of the body are acted upon by the various stimuli in nature ; and these, passing through the sensory nerves into the spinal cord, are received by the brain, constituting the unanalysable primary psychic atoms, or elements—the sensations. These, in turn, are perceived, recorded, remembered, compared, sorted, etc., and serve to make up thoughts, ideas,
judgments, etc., varying in complexity, in certainty, and in correctness according to the quality of the brain-material (its fibre connections) and the richness of its experience. As a resultant of these thoughts, ideas, and judgments, acts are performed, constituting a third primary division of the functions of the brain. These responses, or acts, may be voluntary, the tension of the impulses having passed into the field of consciousness ; or they may be involuntary, having resulted from reactions between the sense organs, spinal cord, and muscles (spinal reflexes, sympathetic reflexes) ; or the involuntary act may, after having been for years a voluntary act (as in walking), by constant repetition cease to be a dominant factor in the field of consciousness (so-called sub-conscious acts).
There is in the brain-substance a certain amount of division of labour, as yet only incompletely worked out. A motor area is known ; likewise a sensory one Areas for the understanding of things seen, heard, smelled, or touched have been localised. General areas in which complex ideas are elaborated are mapped out ; but the brain is so infinitely complex that all of the fibre-tracts, cell-groups, and connections will be known only after many more years of painstaking investigation of the human brain as well as of that of lower animals. The mass of known facts, however, fills many thousands of volumes. No one human mind knows more than a very small fraction of all the facts ascertained concerning the brain.