344 NERVOUS SYSTEM. 



to the cartlia, others along the small curvature, which communi- 

 cate with the ramifications of the right nerve : the other set 

 cross above the stomach to the left side, taking the course of 

 the gastric artery, and join the great semilunar ganglion. The 

 right nerve, smaller than the left, as soon as it reaches the car- 

 dia, splits into many branches which traverse the small curva- 

 ture, where they form communications with the left, and spread 

 their ramifications upon the under part of the organ : some of 

 them run to the pylorus likewise, and others go to join the he- 

 patic plexus. 



Accessory Nerves to the Eighth Pair. 



These nerves are considered as accessory to the two former, in con- 

 sequence of their being all three found together in close connexion 

 at their issue from the cranium. The accessory nerve itself is form- 

 ed within the vertebral canal, by the concurrence and union of se- 

 veral filaments derived from the side of the medulla spinalis, one or 

 two of which may generally be traced down to the place of origin 

 of the fourth or fifth cervical nerve. Along its course into the 

 head it receives many other fine threads from the marrow, and 

 in the cranial cavity joins the par vagum ; with which, and with 

 the nervus glosso-pharyngeus, all inclosed in one and the same 

 sheath, it descends through the foramen lacerum basis cranii. 

 Beneath the atlas, the accessory nerve leaves its companions, 

 and splits into two divisions. — The anterior division runs down- 

 ward and forward, and penetrates the belly of the sterno-max- 

 illaris, among the fasciculi of which it may be followed, trans- 

 mitting numerous lateral twigs in its course, down to the very ori- 

 gin of the muscle. The posterior division turns round the trans- 

 verse process of the atlas, and takes a waving course between 

 the levator humeri and splenius, obliquely across the side of the 

 neck, to the top of the scapula ; where it plunges into the rhom- 

 boideus brevis, and vanishes in the muscular substance. This 

 division receives filaments of communication from several of the 

 cervical nerves, and furnishes ramifications to the muscles over 

 which it passes. The branches of the trunk of the accessory 

 nerve are — 1. To the par vagum, at its exit from the skull. 2. 

 Some twigs to the anterior cervical ganglion. 3. A filament of 

 communication with the sub-occipital nerve. 



Ninth Pair, or Lingua/, 



Arise, behind the eighth pair, from the corpora olivaria ; pass 

 out of the cranium through the foramina condyloidea anteriora ; 

 and are first found, in company with the par vagum, against the 



