Function and innervation of the involuntary m. retroauricularis.

Beside the automatic, obligatory and tonic coinnervation of the involuntary m. retroauricularis in conjugate lateral gaze (oculoauricular phenomenon, nystagmus) several other physiological ways of accidental coinnervation are described. In talking, chewing, swallowing and during involuntary inspiration irregular bursts of innervation may be registered. In sleep regular rhythmic inspiratory innervation is demonstrated as well as myoclonic jerks. With reservation, an allusion is made to rem-sleep. In "nervous subjects" irregular involuntary innervation of the m. retroauricularis might serve as a measurement instrument for the involuntary somatomotor nervous system, i.e. the degree of neurotic tensity. An early myasthenic reaction is gained from the M. retroauricularis in patients with ocular forms of the disease. A common motor nucleus of abducens and facial nerve is discussed. Complementary studies are announced on the various forms of facial paralysis, strabismus and nystagmus. A further diagnostic use is presumed.