THE SYMPATHETIC, MIDDLE CERVICAL GANGLION. 871 



ganglion, and distributes filaments to the wall of the internal carotid. The 

 branch of communication with the third nerve joins it at its point of division; 

 the branch to the fourth nerve joins it as it lies on the outer wall of the cavernous 

 sinus ; other filaments are connected with the under surface of the trunk of the 

 ophthalmic nerve; and a second filament of communication joins the sixth nerve. 



The filament of connection with the ophthalmic ganglion arises from the 

 anterior part of the cavernous plexus ; it accompanies the nasal nerve or con- 

 tinues forward as a separate branch. 



The terminal filaments from the carotid and cavernous plexuses are prolonged 

 along the internal carotid, forming plexuses which entwine round the cerebral and 

 ophthalmic arteries ; along the former vessels they may be traced on to the pia 

 mater ; along the latter, into the orbit, where they accompany each of the sub- 

 divisions of the vessel, a separate plexus passing, with the arteria centralis retinae, 

 into the interior of the eyeball. The filaments prolonged on to the anterior com- 

 municating artery form a small ganglion, the ganglion of Ribes, 1 which serves, as 

 mentioned above, to connect the sympathetic nerves of the right and left sides. 



The inferior or descending branch of the superior cervical ganglion communi- 

 cates with the middle cervical ganglion. 



The external branches are numerous, and communicate with the cranial nerves 

 and with the four upper spinal nerves. Sometimes the branch to the fourth 

 s.->inal nerve may come from the cord connecting the upper and middle cervical 

 ganglia. The branches of communication with the cranial nerves consist of 

 delicate filaments, which pass from the superior cervical ganglion to the ganglion 

 of the trunk of the pneumogastric and to the hypoglossal nerve. A separate 

 filament from the cervical ganglion subdivides and joins the petrosal ganglion of 

 the glosso-pharyngeal and the ganglion of the root of the pneumogastric in the 

 jugular foramen. 



The internal branches are three in number the pharyngeal, laryngeal, and 

 tup <!{<. cardiac nerve. The pharyngeal branches pass inward to the side of the 

 pharynx, where they join with branches from the glosso-pharyngeal, pneumogastric, 

 and external laryngeal nerves to form the pharyngeal plexus. The laryngeal 

 hi- mi-lies unite with the superior laryngeal nerve and its branches. 



The superior cardiac nerve (nervus superficialis cordis) arises by two or more 

 branches from the superior cervical ganglion, and occasionally receives a filament 

 from the cord of communication between the first and second cervical ganglia. It 

 runs down the neck behind the common carotid artery, lying upon the Longus 

 colli muscle, and crosses in front of the inferior thyroid artery and recurrent 

 larvngeal nerve. 



The right superior cardiac nerve, at the root of the neck, passes either in front 

 of or behind the subclavian artery, and along the arteria innominata, to the back 

 part of the arch of the aorta, where it joins the deep cardiac plexus. This nerve, 

 in its course, is connected with other branches of the sympathetic : about the 

 middle of the neck it receives filaments from the external laryngeal nerve ; lower 

 down, one or two twigs from the pneumogastric ; and as it enters the thorax it is 

 joined by a filament from the recurrent laryngeal. Filaments from this nerve 

 communicate with the thyroid branches from the middle cervical ganglion. 



The left superior cardiac nerve, in the chest, runs by the side of the left com- 

 mon carotid artery and in front of the arch of the aorta to the superficial cardiac 

 plexus, but occasionally it passes behind the aorta and terminates in the deep 

 cardiac plexus. 



The anterior branches ramify upon the external carotid artery and its branches, 

 forming round each a delicate plexus, on the nerves composing which small ganglia 

 are occasionally found. These ganglia have been named, according to their posi- 

 tion, intercarotid 2 (placed at the angle of bifurcation of the common carotid), 

 lingual, temporal, and pharyngeal. The plexuses accompanying some of these 



1 The existence of this ganglion is doubted by some observers. 



2 This ganglion is of the same structure as the coccygeal gland (Luschka). 



