294 THE NERVOUS SYSTEM 



Eleventh Nerve (Spinal Accessory). 



Origin. This nerve consists of a cranial portion, acces- 

 sory to the tenth, and a spinal portion. The apparent origin 

 of the cranial root is from the side of the medulla just below 

 the vagus. Its deep origin is in the medulla to the posterior 

 and outer side of the nucleus of the ninth. The apparent 

 origin of the spinal portion is by several filaments from the 

 side of the cord as low down as the sixth cervical nerve. Its 

 deep origin is from a column of cells in the anterior cornu 

 of gray matter of the cord. 



Course and Distribution (Accessory Portion). Passing 

 out to the jugular foramen it is joined by the spinal portion, 

 and sends a few filaments to the ganglion of the root of the 

 tenth ; then leaving the spinal portion it finds exit from the 

 cranium by the jugular foramen, passes over the ganglion of 

 the trunk of the tenth (adherent to it), and is continued 

 chiefly in the pharyngeal and superior laryngeal branches of 

 that nerve (Gray), but in the recurrent laryngeal as well. 



Spinal Portion. Running upward between the two roots 

 of the spinal nerves the spinal portion enters the cranial cav- 

 ity by the foramen magnum, passes outward to the jugular 

 foramen, where it joins the accessory portion to separate 

 from it on passing through that foramen. After leaving the 

 skull it takes a course backward, pierces the sterno-mastoid, 

 crosses the occipital triangle and terminates in the trapezius. 

 It gives branches to the sterno-mastoid and to the cervical 

 plexus. 



Functions. Both roots of this nerve are purely motor, but 

 communication with other nerves gives it a degree of sensi- 

 bility. The fibers from the medulla (accessory) go exclu- 

 sively to the muscles of the larynx and pharynx, while 

 those from the cord (spinal) go exclusively to the sterno- 

 mastoid and trapezius; and section of either root separately 

 is followed by phenomena corresponding to these facts. 

 When both roots are divided there is loss of voice, disturb- 



