Cerebellar Vermis - Comparative Anatomy - in Fish

In Fish

In vertebrates, the cerebellar vermis develops between two bilaterally symmetrical formations located dorsal to the upper end of the medulla oblongata, or rhombencephalon. This is the region of termination for the fibers of the vestibular nerve and lateral line nerves; thus, these are the oldest afferent paths to the cerebellum and cerebellar vermis. In bony fish, or teleosts, it has been proposed that the cerebellar auricles, which receive a large amount of input from the vestibulolateral line system, constitute the vestibulocerebellum and are homologues of the flocculonodular lobe of higher vertebrates along with the corpus cerebelli, which receives spinocerebellar and tectocerebellar fibers. The labyrinth and the lateral line organs of lampreys have structural and functional similarity. An important difference between the two structures is that the arrangement of the lateral line organs are such that they are sensitive to relative motion of the fluid surrounding the animal, whereas the labyriths, having very similar sensing mechanisms, are sensitive to endolymph, providing information concerning the animal's own equilibrium of the body and orientation in space