SPINAL ACCESSORY. 169 



called the muscular branch, penetrates and passes through 

 the posterior portion of the upper third of the sterno-cleido- 

 mastoid muscle, goes to the anterior surface of the trape- 

 zius, which muscle receives its ultimate branches of distri- 

 bution. In its passage through the sterno-cleido-mastoid, 

 it joins with branches from the second and third cervical 

 nerves, and sends filaments of distribution to the muscle. 

 Although the two muscles just mentioned receive numerous 

 motor filaments from the spinal accessory, they are also sup- 

 plied from the cervical nerves ; and, consequently, they are 

 not entirely paralyzed when the spinal accessory is divided. 



Properties and Functions of the Spinal Accessory. Not- 

 withstanding the great difficulty in exposing and operating 

 upon the roots of the spinal accessory, it has been demon- 

 strated that their galvanization produces convulsive move- 

 ments in certain muscles. The most satisfactory experi- 

 ments with relation to the general properties of the roots 

 were made by Bernard. This physiologist cut through 

 the occipito-atloid membranes and galvanized the filaments 

 within the spinal canal. By galvanizing the filaments aris- 

 ing from the medulla oblongata, he produced contractions 

 of the muscles of the pharynx and larynx and no move- 

 ments of the sterno-mastoid and trapezius. Galvanization 

 of the roots arising from the spinal cord produced move- 

 ments of the two muscles just mentioned, and absolutely 

 no movements in the larynx. 1 Bernard has further shown 

 that the roots of the nerve are endowed with recurrent 

 sensibility from the posterior roots of the first three pairs 

 of cervical nerves. 2 In view of these experiments, it is evi- 

 dent that the true filaments of origin of the spinal accessory 

 are motor ; and it is further evident that the filaments from 



J BERNARD, Recherche* experimentales sur leg fonctions du nerf spinal, p. 731. 

 It is stated in a note that this memoir was printed in the Archives de medecine^ 

 in 1844. 



s Loc. cit., p. 730. "We have already fully considered the subject of recur- 

 rent sensibility in the anterior roots of the spinal nerves (see page 81). 



