Physiological Role of Neck Muscles in the Occurrence of Optic Eye Nystagmus: Relationship of Optic Head Nystagmus to Optic Eye Nystagmus in Case of Procainization of Neck Muscles

Abstract

Three guinea-pigs were administered injections of 3 cc of 0.3% procaine solution into the superficial and the deep group of the nuchal muscles respectively, and the optic head and eye nystagmus were observed before and after the injection. Procainization of the superficial group of the nuchal muscles was not found to influence seriously the occurrence of the optic reflexes. On the contrary, procainization of the deep group of the nuchal muscles was noted to inhibit the appearance of the optic reflexes. Inhibition of the optic head nystagmus was paralleled with that of the optic eye nystagmus.

From this fact the conclusion was drawn that the role of the optic head nystagmus in the maintenance of body equilibrium is to facilitate the occurrence of the optic eye nystagmus. As for this mechanism, our opinion is that centripetal impulses from the proprioceptors in the neck muscles, especially those in the deep group of the nuchal muscles, possibly cooperate with impulses from the labyrinth, which also are produced by the head nystagmus, in promoting the activity of the oculomotor nuclei, and thus the optic organ can increase its adaptability to environmental changes.