1036 THE' NERVOUS SYSTEM 



(3) Four or five laryngo-pharyngeal branches come from the superior ganglion and the 

 plexus extending downward from it, and pass forward and medialward, lateral to the carotid 

 vessels, to the wall of the pharynx, where they unite on the middle constrictor with the pharyn- 

 geal branches of the glosso-pharyngeus and vagus, forming with them the pharyngeal plexus, 

 from which branches are distributed to the walls of the pharynx and to the superior and 

 external laryngeal nerves (fig. 787). 



(4) The superior cervical cardiac nerve springs from the lower part of the ganglion or from 

 the trunk immediately below it. It passes downward behind the carotid sheath, either in front 

 of or dorsal to the inferior thyreoid artery, and in fi-ont of the longus colli, and estabUshes 

 communications with the upper cervical cardiac branch of the vagus, the middle cervical cardiac 

 branch of the sympathetic, and with the inferior and external laryngeal nerves. At the root 

 of the neck the nerve of the right side passes in front of or behind the first part of the right sub- 

 clavian artery, and is continued along the innominate artery to the front of the bifurcation of 

 the trachea, where it ends in the deep part of the cardiac plexus. The left nerve passes into the 

 thorax along the front of the left common carotid artery, crosses the front of the arch of the aorta 

 immediately anterior to the vagus, and terminates in the superficial part of the cardiac plexus 

 (fig. 789). Filaments from both the right and left nerves pass to the inferior thyreoid plexus. 



(5) The external carotid nerves (fig. 787) pass forward from the superior cervical ganglion 

 to the external carotid artery, where they divide into branches which anastomose freely to form 

 around the artery the external carotid plexus. This plexus extends to the beginning of the 

 artery, and is continued upon the common carotid artery as the common carotid plexus. From 

 the external carotid plexus, filaments pass to form secondary plexuses around each of the 

 branches of the external carotid artery. These plexuses take the names of the arteries which 

 they follow, namely, the superior thyreoid plexus, lingual plexus, etc. Filaments pass from 

 the external carotid plexus to the glomus caroticum (the carotid gland), and from the superior 

 thyreoid plexus to the thyreoid gland. 



From the external maxillary (facial) plexus passes the sympathetic root of the submaxillary 

 ganglion. 



A part of the internal maxillary plexus is continued upon the middle meningeal artery as 

 the meningeal plexus. From this plexus filaments pass to the otic ganglion, and sometimes 

 a branch, called by English anatomists the external superficial petrossal nerve, passes to the 

 geniculate gangHon. 



(6) Small branches to the ligaments and bones of the upper part of the vertebral column. 



(7) The internal carotid nerve (ascending branch) and plexus have been described with 

 the cephalic portion of the sympathetic system. 



2. The Middle Cervical Ganglion 



The middle cervical ganglion is small and somewhat triangular in outline. It 

 is sometimes absent. Its position is variable, but it commonly lies about the 

 level of the cricoid cartilage, in front of the bend of the inferior thyreoid artery 

 (fig. 787), and it is associated with the superior cervical ganglion and with the 

 inferior cervical ganglion by the trunk of the gangliated cord. From the lower 

 part of the middle ganglion some filaments pass dorsal to the subclavian artery, 

 while others pass in front of and beneath that artery and anastomose with the 

 first-mentioned filaments to form a loop, the ansa subclavia (ansa Vieussenii) 

 (figs. 751, 787). Filaments from this loop to the inferior cervical ganglion thus 

 form another communication between the middle and inferior cervical ganglia. 



Connections. — The middle cervical ganghon gives off four or more rami. 

 Two (a and h) are grey rami communicantes which connect the middle ganglion with the 

 anterior primary branches of the fifth and sixth cervical nerves. 



(c) One or more peripheral branches pass along the inferior thyreoid artery and anastomose 

 with branches from the superior and middle cardiac nerves and from the inferior cervical 

 ganghon, thus taking part in the formation of the inferior thyreoid plexus, from which branches 

 pass to the thyreoid gland. 



(d) The middle cardiac nerve arises by one or more branches from the ganglion, or from 

 the trunk of the cord, and pas.ses downward dorsal to the common carotid artery and, on the 

 right side, either in front of or dorsal to the subclavian artery, and then along the innominate 

 artery to the deep part of the cardiac plexus (figs. 787 and 780). It is frequently larger than 

 the superior cardiac nerve. On the left side the nerve runs between the subclavian and common 

 carotid arteries. On both sides the nerve communicates with the inferior laryngeal nerve and 

 external laryngeal nerve. 



The middle cervical ganglion also gives branches to the common carotid plexus. 



3. The Inferior Cervical Ganglion 



The inferior cervical ganglion is irregular in form. It is larger than the 

 middle cervical ganglion, and it lies deeply in the root of the neck dorsal to the 

 vertebral artery or the first part of the su})clavian artery, and ventral to the 

 interval bcstween the transverse processes of the last cervical and the first thoracic 

 vertebrie (figs. 759, 701). It is connected with the middle cervical ganglion by 



