Axon Trajectories in the Auditory Brainstem

Abstract

Abstract This chapter summarizes what is known about the organization of the axons that make up the white matter of the auditory brainstem. The sources of the axons in each of the major fiber bundles (the dorsal and intermediate acoustic striae, the ventral acoustic stria or trapezoid body, and the lateral lemniscus) are reviewed, and, where information is available, the organization of specific groups of axons within the fiber bundles is described. The chapter collects the extensive but scattered information about axon trajectories into one place, both to provide a summary of what is known and also to indicate important gaps in our knowledge. The emphasis is almost entirely on the routes followed by groups of axons over the relatively long distances between structures and on the organization of specific types of axons within the fiber bundles; information about the termination patterns of the axons can be obtained from the references cited and throughout the chapter. Because knowledge about axon trajectories has considerable practical value (as, for example, in designing and interpreting both anatomical and physiological studies), the most useful information is species specific. Fortunately, at least at our current level of understanding, the components and relative positions of the major fiber bundles are remarkably similar across species (undoubtedly reflecting a common mammalian developmental plan).