WONDERFUL ORGANISATION

Hawera Star, Volume XLV, 16 January 1926, Page 11

WONDERFUL ORGANISATION

DISCOVERY of importance relating to the problem of why people with diseases of the inner car, and many deaf mutes, are apt to be seized with giddiness and vertigo and loss of control of their 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. McNally,. assistant to Dr. Birkett, 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 ear controlling equilibrium and posture of the human body. -The inner car, 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 displacements of the head and body. When this “compass-’ is in good working 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 cr patient with ear disease, this “compass” may not bo 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 eves shut under water and contact with the ground is lost, deaf mutes, tend to lose their sense of direc-

BODY'S COMPASS IN INNER EAR

tion and 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 to swim, since with the loss of contact with the ground sense of direction is less perfect and becomes lost when the eyes are closed. ,

In their researches, Professor Tait and Dr. McNally overcame outstanding experimental difficulties, and not only advanced 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 as the utricular mascula. The semicircular 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 move-ments-of one particular limb—the right anterior with the. right fore-limb, the right posterior with * the right hindlimb, and so on. Adequate stimulation of any canal, it . was found, produces an excessively quick response. When a man who is walking catches us foot in some obstacle and. trips, it i 3 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 flung forward and. to one or other side to save him in Ill's, 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 force.