THE ELEVENTH OR SPINAL ACCESSORY NERVE. 753 



is altered and weak in timbre. The recurrent laryngeal nerves may be paralyzed in bulbar 

 paralysis or after diphtheria, when it usually affects both sides ; or they may be affected by the 

 pressure of aneurisms of the aorta, innominate or subclavian arteries; by mediastinal tumors; 

 by bronchocele; or by cancer of the upper part of the oesophagus, when the paralysis is often 



unilateral. 



The Eleventh Pair (Figs. 403, 404). 



The Eleventh or Spinal Accessory Nerve consists of two parts : one, the acces- 

 sory part to the vagus, and the other the spinal portion. 



The bulbar or accessory part is the smaller of the two. Its superficial origin 

 is by four or five delicate filaments from the side of the medulla, below the roots 

 of the vagus. Its deep origin may be traced to a nucleus of gray matter at the 

 back of the medulla, dorao-lateral to the hypoglossal nucleus, and extending as far 

 down as the intermedio-lateral tract of the spinal cord. It passes outward to the 

 jugular foramen, where it interchanges fibres with the spinal portion or becomes 

 united to it for a short distance ; it is also connected, in the foramen, with the 

 upper ganglion of the vagus by one or two filaments. It then passes through the 

 foramen, and becoming again separated from the spinal portion it is continued 

 over the surface of the ganglion of the trunk of the vagus, being adherent to its 

 surface, and is distributed principally to the pharyngeal and superior laryngeal 

 branches of the pneumogastric. Through the pharyngeal branch it probably sup- 

 plies the muscles of the soft palate (see page 331). Some few filaments from 

 it are continued into the trunk of the vagus below the ganglion, to be dis- 

 tributed with the recurrent laryngeal nerve, and probably also with the cardiac 

 nerves. 



The spinal portion is firm in texture. Its superficial origin is by several fila- 

 ments from the lateral tract of the cord, as low down as the sixth cervical nerve. 

 Its deep <>ri</iti may be traced to the intermedio-lateral tract of the gray matter of 

 the cord. This portion of the nerve ascends between the ligamentum denticulatum 

 and the posterior roots of the spinal nerves, enters the skull through the foramen 

 magnum, and is then directed outward to the jugular foramen, through which it 

 passes, lying in the same sheath as the pneumogastric, but separated from it by a 

 fold of the arachnoid. In the jugular foramen it receives one or two filaments 

 from the accessory portion. At its exit from the jugular foramen it passes back- 

 ward, either in front of or behind the internal jugular vein, and descends obliquely 

 behind the Digastric and Stylo-hyoid muscles to the upper part of the Sterno- 

 mastoid. It pierces that muscle, and passes obliquely across the posterior triangle, 

 to terminate in the deep surface of the Trapezius. This nerve gives several 

 branches to the Sterno-mastoid during its passage through it, and joins in its sub- 

 stance with branches from the second cervical, which supply the muscle. In the 

 posterior triangle it joins with the second and third cervical nerves, while beneath 

 the Trapezius it forms a sort of plexus with the third and fourth cervical nerves, 

 and from this plexus fibres are distributed to the muscle. 



Surgical Anatomy. In cases of spasmodic torticollis in which all palliative treatment has 

 failed, division or excision of a portion of the spinal accessory nerve has been resorted to. This 

 may be done either along the anterior or posterior border of the Sterno-mastoid muscle. The 

 former operation is performed by making an incision from the apex of the mastoid process, 

 three inches in length, along the anterior border of the Sterno-mastoid muscle. The anterior 

 border of the muscle is denned and pulled backward, so as to stretch the nerve, which is then to 

 be sought for beneath the Digastric muscle, about two inches below the apex of the mastoid 

 process. The other operation consists in making an incision along the posterior border of the 

 muscle, so that the centre of the incision corresponds to the middle of this border of the mus- 

 cle. The superficial structures having been divided and the border of the muscle defined, the 

 nerve is to be sought for as it emerges from the muscle to cross the occipital triangle. When 

 found, it is to be traced upward through the muscle, and a portion of it excised above the point 

 where it gives off its branches to the Sterno-mastoid. In this operation one of the descending 

 branches of the superficial cervical plexus is liable to be mistaken for the nerve. 

 48 



