Figure 1.

Anatomy and morphology of the EVS across vertebrates. Studies that directly investigated EVS anatomy and morphology were separated under the following categories-cell body clustering, innervation pattern, and dendritic arborization. Studies that assessed more than one category are mentioned in each respective category they investigated. Where more than one cell body cluster was observed, the number of clusters is labeled and depicted with the respective number of blue pictorial clusters. Asterisk next to Lysakowski and Singer (2000) denotes one cluster likely projecting to middle ear instead of peripheral vestibular labyrinth. Uni- and bilateral projections are also labeled and depicted with pink lines from a coronal brainstem schematic out towards the inner ear (drawings not to scale). Only one bilateral projection is drawn for Meredith and Roberts (1987) eel as they denoted it as a minor finding. Expansive green lines along the brainstem tegmentum denote widespread arborization of dendrites, and shorter green lines depict restricted arborization, as labeled. Nonmammalian species included all animals groups not classified as mammals.