THE AURICULO-GENITAL REFLEX IN CATS

¹ The Division of Neurology and Neuro-surgery of the University of Chicago Clinics, Chicago, Illinois

A reflex is described which can be obtained in about 90 per cent. of cats by manual stimulation of the external ear. The response consists of contraction of subcutaneous muscle about the genital organs. The pathway involved is shown to be afferent over the auricular branch of the vagus, efferent over the eighth cervical and first thoracic anterior roots, the brachial plexus, and over a long nerve coursing down the lateral abdomen and then medially to the genitalia. The efferent pathway crosses above the second cervical segment, probably in the brain stem (fig. 2). The response to aural stimulation is strictly a crossed one, the almost symmetrical contraction of the muscle being due to partial dual innervation of the muscle by the nerves of the two sides. Evidence is adduced to show that the absence of the reflex in certain instances is probably due to local conditions affecting the ears. The subcutaneous muscle of the genitalia is probably a separated portion of the cutaneus maximus muscle.