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THE EQUILIBRIUM FUNCTION OF THE VERTEBRATE LABYRINTH
Author(s) -
LÖWENSTEIN. OTTO
Publication year - 1936
Publication title -
biological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.993
H-Index - 165
eISSN - 1469-185X
pISSN - 1464-7931
DOI - 10.1111/j.1469-185x.1936.tb00499.x
Subject(s) - vestibular system , reflex , otolith , anatomy , vertebrate , biology , inner ear , french horn , appendage , semicircular canal , organ of corti , neuroscience , physics , acoustics , fish <actinopterygii> , biochemistry , fishery , gene
Summary. 1. The vertebrate labyrinth can be divided into a pars superior, consisting of the utriculus and the semicircular canals, and a pars inferior, consisting of the sacculus and its various appendages. 2. Only the pars superior is concerned with the maintenance of muscle tone and with reflex reactions to gravity and to linear and angular accelerations. This has been demonstrated for fishes, amphibia and mammals, and, although the evidence is not completely satisfactory, it probably holds for reptiles and birds as well. The pars inferior takes no part in any of these functions (again with the above reservation as to reptiles and birds), but, even in those vertebrates which lack the organ of Corti, is concerned with sound reception. Breuer's theory of the localisation of the non‐acoustic function of the labyrinth has thus been shown to be erroneous. 3. Attempts have been made to discover which of the receptor endings of the pars superior are involved in each of its functions, by eliminating separately the various endings. The results obtained are not entirely consistent. Production of the static reflexes and of the reflexes to centrifugal force and fast linear acceleration is in all probability the main function of the otolith organ (utriculus). It appears, however, that the assumption that the otolith organ is purely static in function is incorrect, for it has been shown that the utriculus can be involved in dynamic responses to rotations. The main function of the semicircular canals is the release of the dynamic reflexes. It has, however, been claimed that the vertical canals take part in the production of static reflexes as well. Both the utriculi and the semicircular canals are involved in the maintenance of muscle tone. 4. In the discussion of the general conclusions as to the function of the utriculi and of the semicircular canals it is shown that one of the important functional differences between the two receptors consists in their different reaction time, which may be due to the difference in their auxiliary structures and to a different pattern of their nervous connection with the effector organs.