Three-dimensional computer-aided reconstruction of the pontobulbar body.

The pontobulbar body (PBB) has a crescent-like shape and runs along the caudal border of the cochlear nuclei (CN) on the lateral surface of the brain stem and then extends rostrally to the root of the trigeminal nerve. Three-dimensional computerized reconstruction methods have been used to produce two models that show the surface topography of the PBB and CN together, while other models revealed the appearance of different sides of the PBB only. The models accurately localized the common boundaries between the PBB and CN. Inside the brain stem, the boundary between the ventral CN and PBB was not always clear in sections stained for cell bodies and myelinated fibers. Close relationships between the PBB and pontine nuclei in the ventral portions of the pons were demonstrated. The reconstructions also showed the position of the tenia of the inferior velum of the fourth ventricle in relation to the PBB and CN. In contrast to the CN, only a relatively small portion of the PBB was located within the fourth ventricle. Results may be useful to work underway in this institution on implantation of the central electro-auditory prosthesis. Results might also be useful for further development of the surgical anatomy of the cerebellopontine angle.