Breuer’s Experiments on the Semicircular Canals and Otolith Organs

After his groundbreaking work in the mid-1860s, Josef Breuer continued to perform experiments on the inner ear balance receptors in animals. He studied the macules of fish, reptiles, and birds and noted that all these creatures had three macules arranged in the planes of the semicircular canals, perpendicular to one another. By contrast, mammals had only two macules located in the utricle (horizontal plane) and saccule (vertical plane), again perpendicular to each other. He developed the concept of “slip” to describe the movement of the otoconial membrane over the underlying sensory epithelium that occurred with linear displacement or gravity. He developed a mathematical model to hypothesize that in humans there was only one combination of responses from the two macules on each side for a single head position in space.