The membranous labyrinth lies enclosed in the very hard petrous part of
the temporal bone and, as the name implies, its structure is extremely
complex. This may explain why our knowledge of this organ and the
vestibular sensory regions within it, is not yet satisfactory. In recent
years the rapid development of space research has provided a power- ful
stimulus to our interest in the vestibular apparatus. This has found
expression in annual symposia, in which the role of the vestibular
organs in the exploration of space is discussed. However, little is
known as yet about the influence upon the equilibrial apparatus, during
space flight, of weightlessness and other related conditions. The inner
ear has also acquired increased significance from an otosurgical point
of view. Operations are today performed in regions previously
inaccessible to surgery. This requires exact knowledge of anatomical
details and of relations between the different structures in the inner
ear.