136 INNERVATION. [CHAP. XXI. 



and subdividing as they ascend, so as to form a plexus around that 

 artery, the cavernous or carotid plexus. With this plexus numerous 

 communications take place : there is one with Meckel's ganglion, 

 another with the tympanic plexus; a branch to the ophthalmic gan- 

 glion, and one or two large ones to the sixth nerve, which formerly 

 were regarded as roots of the sympathetic from that nerve; also one 

 or two filaments to the third pair, and small branches attaching them- 

 selves to the ramifications of the carotid artery within the cranium. 

 Communications exist between the superior cervical ganglion, and 

 the several portions of the eighth pair, and the ninth pair at their 

 exit from the cranium. 



Inferiorly the superior cervical ganglion is continued into a cord 

 of communication with the middle, or, when that is wanting, with 

 the inferior cervical ganglion. 



The arterial and visceral branches of the superior cervical ganglion, 

 are, 1 . The delicate gray nerves to the internal carotid artery, (nervi 

 molles of Scarpa,) which, with branches from the glosso-pharyngeal, 

 and vagus, form a plexus round the internal, external and common 

 carotid arteries. 2. Pharyngeal branches, which, with filaments from 

 the vagus and glosso-pharyngeal, form the pharyngeal plexus. 3. La- 

 ryngeal branches accompanying the superior laryngeal branch of the 

 vagus. 4. A cardiac nerve, not always present, and very variable 

 in size, (the superior cardiac nerve of Scarpa,) which either united 

 with a similar nerve from the middle, or inferior cervical ganglion, 

 or alone, passes along the carotid artery into the chest, to contribute 

 to form the plexus of nerves belonging to the heart. 



The middle cervical ganglion is very inconstant; it is placed 

 opposite the fifth or sixth cervical vertebra, and besides the branches 

 of continuation with the third, fourth, and fifth cervical nerves, it 

 gives off one visceral branch, namely, the middle cardiac nerve, (nervus 

 cardiacus magnus of Scarpa,) which is the largest of the three, and 

 in default of the ganglion comes off from the intercommunicating 

 cord. This nerve has a similar course to the inferior one; it 

 is often absent, and its place is then supplied by filaments, which 

 take a similar course, but are derived from the superior nerve, or 

 from the vagus. 



The inferior cervical ganglion. This ganglion is situate very low 

 down in the neck, and is very deep seated; it corresponds to the 

 transverse process of the last cervical vertebra, to the head of the 

 first rib, and is closely connected with the origin of the vertebral 

 artery. It is frequently fused with the first thoracic ganglion, and 

 is connected above with the middle, or, in its absence, with the 



