Electromyographic studies on the coordination of antagonistic muscles in cases of abducens and facial palsy.

FROM earlier electromyographic investigations of the human eye muscles (Bjork and Kugelberg, 1953b), we know that the internal and external recti muscles manifest a pronounced activity on direct forward gaze. During slow lateral movements of the eyeball, a gradual increase in this activity takes place in the agonist and a corresponding decrease in the antagonist, but even in extreme positions of the gaze the activity in the antagonist does not usually disappear entirely. In rapid movements, on the other hand, there occurs a brief acceleration of activity in the agonist and complete inhibition in the antagonist. The levator palpebrae superioris muscle also shows intense activity with the gaze forward. Lowering of the lid is accompanied by a gradual diminution of the activity which only disappears entirely when the eye has reached the position of extreme downward gaze. Blinking causes an abrupt inhibition of all activity in the levator with a simultaneous contraction of the orbicularis oculi. The object of the present paper is further to illustrate, with the aid ofelectromyography, the coordination of antagonistic muscles acting upon the human eye and eyelids by an analysis of cases in which movement is grossly disturbed. Thus cases have been studied of total abducens palsy and total facial palsy, and, furthermore, of non-paretic cases in which the action of the muscles was artificially opposed by traction on the eyeball. These investigations are closely related to Sherrington's classical studies on the posture and movements of the eye of the monkey after the intracranial section of nerves. Sherrington considered the cooperation between the eye muscles to be a typical example of reciprocal innervation of the kind which he had demonstrated in the limbs.