THE PNEUMO-GASTRIC XERVE. 657 



supplies nerves to the organs of voice and respiration, to the alimentary 

 canal as far as the stomach, and to the heart. 



Surface attachment. — This nerve arises from the restiform body 

 of the medulla, by twelve or fifteen fine roots, beneath and in a line 

 Avith the roots of the glosso-pharyngeal nerves. 



Deep origin. — The fibres pass inwards and backwards thronoh the 

 medulla to a column of nerve-eclls beneath the lowest part of the floor 

 of the fourth ventricle, where they cause a prominence on the surface. 

 At the point of the calamus scriptorius the nuclei are in contact in 

 the middle line, but a little higher up they are separated by the nuclei 

 of the hypoglossal nerve. 



Course and distribution. — The filaments by which this nerve 

 springs from the medulla oblongata close below those of the glosso- 

 pharyngeal nerve are arranged in a flat fasciculus, which is directed 

 outwards with that nerve, across the flocculus to the jugular foramen. 



Fig. 347. — Diagram of the Roots Fig. 347. 



AND Anastomosing Branchks of 

 THE Nerves of the Eighth Pair 

 and Neighbouring Nerves (from 

 Sappey after Hii-scbfeld and Le- 

 veille). 



1, facial nerve ; 2, glosso-pharyn- 

 gealwitli tbe petrous ganglion repre- 

 sented; 2', connection of the digastric 

 branch of the facial nerve with 

 theglosso-ijharyngeal neiTe; 3, pncu- 

 mo-gastric, with both its ganglia re- 

 piesented ; 4, spinal accessory ; 5, 

 hypoglossdl ; 6, superior cervical 

 ganglioQ of the sympathetic ; 7, loop 

 of union betweea the two tirst cer- 

 vical nerves; 8, carotid branch of 

 the sympathetic ; 9, nerve of Jacoh- 

 r-ou (tympanic), given off from the 

 ■petrous ganglion ; 10, its filaments 

 to the iympathetic ; 11, twig to the 

 Eustachian tube; 12, twig to the 

 fenestra ovalis ; 13, twig to the 

 fenestra rotunda ; 14, twig of union 

 with the small superficial petrosal; 

 15, twig of union with the large 

 superficial petrosal; 1*5, otic gang- 

 lion ; 17, branch of the jugular 

 fossa, giving a filament to the 

 petrous ganglion ; 18, union of the 

 spinal accessory with tlie pneumo- 

 gastric ; 19, union of the hypo- 

 glossal with the first cervical nerve ; 

 20, union between the sterno-mastoid 

 branch of the spinal accessory and 

 that of the second cervical nerve ; 21, pharyngeal plexus ; 22, superior laryngeal nerve ; 

 23, external laryngeal ; 24, middle cervical ganglion of the sympathetic. 



In passing through the opening at the base of the skull the pneumo- 

 gastric nerve is contained in the same sheath of dura mater, and sur- 

 rounded by the same tube of arachnoid membrane as the spinal 

 accessory nerve ; but it is separated from the glosso-pharyngeal nerve 

 by a process of membrane. In the foramen the filaments of the nerve 



