THE BODY’S COMPASS

Manawatu Times, Volume XLIX, Issue 3247, 18 January 1926, Page 7

THE BODY’S COMPASS

IN THE XJStNER EAR. CANALS AND LIMB MOVEMENTS. A discovery of importanee relating to the problem of why people with diseases of the inner ear and many deaf mutes, are apt to be seized with giddiness and vertigo and loss of control of thoir limbs, has been made by co-workers at McGill University, Professor John Tait, Morley Drake professor of physiology and director of experimental medicine, and Dr. W. J. WdNally, assistant- to Dr. Blrkott, professor of otolaryngology. These two men have carried out with complete success investigations on the as yet little understood mechanism of that part of the inner oar controlling equilibrium and posture of the human body. j Acts Like Compass.

The inner ear, on which the researches have been conducted, contains, in addition to the organ of hearing, an elaborate apparatus, which is analogous to the compass of an airplane and which gives information in relation to the field of gravity and to various accelerations and dis placements of the head and bpdy When this “compass” ia m good workmg order through the perfect condition of the inner ear mechanism, as in persons of normal hearing, there is full control of the limbs. In the case of a deaf mute or patient with car disease, this “compass” may not be in good working order, and giddiness, unsteadiness of the limbs and interference with equilibrium is the result. In the dark, when the assistance rendered by the eyes is interfered with, or when swimming with eyes shut under water and contact with the ground is lost, deaf mutes tend to lose their sense of direction an,d become disoriented. For this reason, it is pointed out. It is more dangerous for a deaf mute or a person with disease of the Inner ear 10 swim, since with the loss of contact with the ground sense of direction is less perfect and becomes lost when the eyes are closed. Automatic Adjustment,

In their researches. Professor Tait and Dr. McNally overcame experimental difficulties, and not only ad. vanced knowledge with regard to the general principles of the problem of equilibrium but obtained clear and definite knowledge of the function of each individual canal in the set of six in the Inner ear. They also established the function of the organ known os the utricular mascula. The semi-circular canals in the Inner ear are arranged in pairs in three rectangular divisions of space. They found that each of the four vertically placed canals is associated with the movements of one particular limb—• the right anterior with tno right forelimb, the right posterior with the right hind-limb, and so on. Adequate stimulation of any canal, it was found produces an excessively quick response. When a man in walking, catches his foot in some obstacle and trips, it is through one or other of the two anterior vertical canals that, even before he himself has time to plan any movement by his own will, the appropriate arm is automatically fiung forward and to one or other side to save him in his fall. The utricular mascula. it was found, is exclusively associated with reactions to a uniform field of force such as gravity, uniform linear acceleration or centrifugal foro%