The Afferent Course of the Oculorespiratory Reflex of the third, fourth, and sixth Cranial Nerves

¹ Department of Ophthalmology and the Oscar Johnson Institute, Washington University School of Medicine, St. Louis, Mo.

Afferent components of the motor nerves to the extrinsic eye muscles were investigated by stimulation and degeneration studies. These studies revealed that: 1. Afferent fibers mediating respiratory responses were present only in the intraorbital portions of the third, fourth, and sixth cranial nerves. 2. These afferents were distributed to, and carried by, the ophthalmic division of the fifth cranial nerve prior to its exit from the cavernous sinus. 3. Muscle twitch threshold and the threshold for production of respiratory responses were identical, suggesting that the afferent components were of the large fiber-sized variety. 4. Histologic studies following intracranial sectioning of the third nerve confirmed the presence of surviving large-sized afferent fibers.