408 



HYPOGLOSSAL NERVE. 



SPINAL ACCESSORY NERVE. The spinal accessory nerve arises by 



several filaments from the side of the 

 spinal cord as low down as the fourth 

 or fifth cervical nerve, and ascends 

 behind the ligamentum denticulatum, 

 and between the anterior and poste- 

 rior roots of the spinal nerves, to the 

 foramen lacerum posterius. It com- 

 municates in its course with the pos- 

 terior root of the first cervical nerve, 

 and entering the foramen lacerum 

 becomes applied against the poste- 

 rior aspect of the ganglion jugulare 

 of the pneumogastric, being con- 

 tained in the same sheath of dura 

 mater. In the jugular fossa it di- 

 vides into two branches ; the smaller 

 joins the pneumogastric immediately 

 below the jugular ganglion, and con- 

 tributes to the formation of the pha- 

 ryngeal nerve ; the larger or true 

 continuation of the nerve passes 

 backwards behind the internal jugu- 

 lar vein, and descends obliquely to the upper part of the sterno-mastoid 

 muscle. It pierces the sterno-mastoid, and then passes obliquely across 

 the neck, communicating w r ith the second, third, and fourth cervical 

 nerves, and is distributed to the trapezius. The spinal accessory sends 

 numerous twigs to the sterno-mastoid in its passage through that muscle, 

 and in the trapezius the nervous filaments may be traced downwards to 

 its lower border. 



The pneumogastric and spinal accessory nerves together (nervus vagus 

 cum accessorio) resemble a spinal nerve, of which the former with its 

 ganglion is the posterior and sensitive root, the latter the anterior and 

 motor root. 



NINTH PAiR.f HYPOGLOSSAL NE#VE (lingual). The hypoglossal nerve 

 arises from the groove between the corpus pyramidale and corpus olivare 



* The anatomy of the side of the neck, showing the nerves of the tongue. 1. A frag- 

 ment of the temporal bone containing the meatns auditorius externus, mastoid, and sty- 

 loid process. 2. The stylo-hyoid muscle. 3. The stylo-glossus. 4. The stylo-pharyn- 

 geus. 5. The tongue. 6. The hyo-glossus muscle ; its two portions. 7. The genio-hyo- 

 glossus muscle. 8. The genio-hyoideus ; they both arise from the inner surface of the 

 symphysis of the lower jaw. 9. The sterno-hyoid muscle. 10. The sterno-thyroid. 

 11. The thyro-hyoid, upon which the thyro-hyoidean branch of the hypoglossal nerve is 

 seen ramifying. 12. The omo-hyoid crossing the common carotid artery (13), and in 

 '.ernal jugular vein (14). 15. The external carotid giving , off its branches. 10. The 

 internal carotid. 18. The gustatory nerve giving off a branch to the submaxillary gan 

 glion (18), and communicating a little further on with the hypoglossal nerve. 19. The 

 submaxillary, or Wharton's duct, passing forwards to the sublingual gland. 20. The 

 giosso-pharyngeal nerve, passing in behind the hyo-glossus muscle. 21. The hypoglos- 

 sal nerve curving around the occipital artery. 22. The descendens noni nerve, form- 

 ing a loop with (23) the communicans noni, which is seen to be arising by fila- 

 ments from the upper cervical nerves. 24. The pneumogastric nerve, emerging from 

 I'etween the internal jugular vein and common carotid artery, and entering the chest. 

 5/5. The faHal nerve, emerging from the stylo-mastoid foramen, and crossing the exter- 

 mil carotid artery. 



t The twelfth pair according to the arrangement of Soemmermg. 



