The Vestibular Nuclear Complex and Related Structures

Abstract

The reptilian vestibular complex is usually divided into at least five nuclei (Weston 1936), i.e., the nucleus vestibularis dorsolateralis (also described as the superior vestibular nucleus: Beccari 1911 ; Larsell 1926; Stefanelli 1944a), the nucleus vestibularis ventrolateralis, the nucleus vestibularis tangentialis, the nucleus vestibularis ventromedialis, and the nucleus vestibularis descendens (or inferior: Beccari 1911; Stefanelli 1944a). In turtles, in addition a nucleus vestibularis superior can be distinguished as a subdivision of the dorsolateral vestibular nucleus (Weston 1936; Cruce and Nieuwenhuys 1974; Miller and Kasahara 1979; ten Donkelaar and Nieuwenhuys 1979; Bangma et al. 1983). Stefanelli (1944 a, b; see also Schwab 1979; ten Donkelaar and Nieuwenhuys 1979) noted the considerable differences in the development of the vestibular nuclei and their connections. The ventrolateral and dorsolateral vestibular nuclei are strongly developed in those reptiles with wholly or partly quadrupedal locomotion, whereas the tangential nucleus is particularly large in species with serpentine movements.