Anatomical relationships of the cochlear nuclei and the pontobulbar body: possible significance for neuroprosthesis placement.
The pontobulbar body (PBB) is located in the cerebellopontine angle caudally to the cochlear nuclear complex (CN). We found the common boundary between these two structures on the surface of the brain stem as well as within it. We used the Kluver-Barrera staining technique to characterize different neuronal types adjacent to the boundary. Although the majority of them in the CN were globular, we also saw a substantial number of spherical neurons. Neurons in the PBB were substantially different in shape and were mainly angular. The boundary between the PBB and CN at their closest contact runs around the caudal side of the ventral cochlear nucleus and the most proximal part of the eighth nerve. In the more dorsal region, the PBB is completely separated from the CN by the brain stem tissue. In the ventral region, the PBB runs between the seventh and eighth nerves, and it is adjacent to both. These results might aid accurate placement of the central electroauditory prosthesis and further understanding of the general anatomy of the cerebellopontine angle.