Observations on the innervation of the sternomastoid muscle.

Nine out of fifteen cases having division of the spinal component of the accessory nerve and the upper cervical motor roots as treatment for spasmodic torticollis had residual movements in the sternomastoid of sufficient magnitude to make further surgery necessary before the muscle was effectively paralysed. These observations imply a more complex innervation for the muscle than is to be found in most anatomical texts.