Histological demonstration of muscle spindles in the tongue of the rat.

The presence and distribution of neuromuscular spindles in the lingual musculature of the laboratory rat is described. The findings counter the commonly held belief that neuromuscular spindles are not found in the tongue musculature of non-primate mammals. The hypothesis that fundamentally different neural systems control lingual movements in primate and non-primate mammals therefore cannot be supported. The differences in the distribution of spindles in primate and non-primate mammals may be related to the patterns of lingual movements and the distribution of muscle fibre types.