NEEVES OF THE NECK 335 



F. The Nerves of the Neck. 



Expose and clean the following nerves on either the right 

 or the left side of the neck. 



1. The spinal accessory nerve, the eleventh cranial nerve, 



leaves the skull at the foramen lacerum posterius, 

 between the auditory capsule and the ex-occipital 

 bone, in company with the pneumogastric and glosso- 

 pharyngeal nerves. Outside the skull it runs almost 

 vertically downwards for about half an inch, and then 

 divides into branches distributed to the sterno-mastoid 

 and other muscles. 



The branch to the sterno-mastoid has already been seen 

 (p. 333). Follow this bach to its junction with the main stem 

 of the nerve, and then trace this latter up to the base of the 

 skull. 



2. The hypoglossal nerve, the twelfth cranial, is a stout 



nerve which leaves the skull by the condylar fora- 

 mina, immediately behiad the foramen lacerum pos- 

 terius, and lies at first very close to the pneumo- 

 gastric, glosso-pharyngeal, and spinal accessory nerves. 

 Outside the skuU it runs downwards and inwards 

 for about half an inch, and then turns forwards, 

 crossing ventral to the carotid artery at its point 

 of division into internal and external carotids. It 

 then runs forwards and inwards, along the dorsal 

 surface of the stylo-hyoid muscle, and parallel to 

 the posterior comu of the hyoid, to the base of the 

 tongue, the muscles of which it supplies. 



The hypoglossal nerve is readily found, where it turns for- 

 wards between the carotid artery and the stylo-hyoid muscle ; 

 and should be followed from this point backwards to the skull, 

 and forwards to the tongue. 



a. The ramus descendens noni is a branch of the hypo- 

 glossal, which arises from the main nerve just 

 before it reaches the carotid artery. It runs 

 back along the outer border of the carotid for 



