THE SYMPATHETIC SYSTEM OF NERVES. 1359 



cranium. The small ganglia connected with the trigeminal nerve the ciliary, the 

 spheno-palatine, the otic and the submaxillary are regarded as outlying nodes be- 

 longing to the cephalic continuation of the gangliated cord. 



The dominant characteristic of this portion is the absence of white rami, the 

 spinal fibres present reaching the cervical region from the upper thoracic nerves by 

 way of the association cord between the highest thoracic and lowest cervical gang- 

 lion, around whose cells, as well as those of the higher cervical ganglia, the processes 

 of the spinal neurones end. 



The distribution of the cervical portion of the cord includes pupillo-dilator 

 fibres, cardio-accelerator fibres, vasomotor fibres to the arteries of the head, neck and 

 upper extremities, pilomotor fibres to the integument of the head and neck, motor 

 fibres to the involuntary muscles of the orbit and eyelids and secretory fibres to the 

 glands. The branches consist, as elsewhere, of two groups, somatic and visceral, the 

 former reaching their area of distribution by way of certain cranial and spinal nerves, 

 and the latter, either alone or in conjunction with other nerves, forming plexuses 

 which accompany blood-vessels and supply various viscera and vessels of the head, 

 neck and thorax. 



The ganglia of the cervical portion include a superior, a middle and an inferior. 



The Superior Cervical Ganglion. The superior cervical ganglion (g. cervi' 

 cale superius) (Fig. 1077) is the largest of the entire sympathetic series, measuring 

 2-3 cm. in length and 4-6 mm. in width. It rests posteriorly on the rectus capitis 

 anticus major muscle opposite the second and third cervical vertebrae, with the 

 internal carotid artery anterior to it and the vagus nerve to its lateral aspect. With 

 the typical reddish-gray hue of the sympathetic ganglia, it is fusiform in outline, 

 although it may present constrictions, usually three, which indicate its composition of 

 four fused ganglia. 



The somatic branches consist of (i) rami communicantes and (2) some of 

 the communicating branches to the cranial nerves. 



1. The rami communicantes consist of four gray rami which join the anterior 

 primary divisions of the first four cervical nerves. 



2. The communicating branches to the cranial nerves are given off from the 

 upper portion of the ganglion, (i) one joining the petrous ganglion of the glosso- 

 pharyngeal, (2) others entering the ganglia of the root and trunk of the vagus and 

 (3) another joining the hypoglossal nerve. In addition to these there is frequently 

 given off from the lower portion of the ganglion (4) a branch which joins the exter- 

 nal laryngeal nerve. 



The visceral branches comprise : (i) the pharyngeal , (2) the superior cervi- 

 cal cardiac , (3) the vascular and (4) the vertebral. 



1. The pharyngeal branch or branches (rr. laryngopharyngei) arises from 

 the antero-mesial aspect of the ganglion and courses obliquely inward and downward 

 posterior to the carotid sheath to reach the surface of the middle constrictor of the 

 pharynx. Here it unites with the pharyngeal branches of the glosso-pharyngeal and 

 vagus nerves to form the pharyngeal plexus (page 1269), from which fibres are 

 distributed to the muscles and mucous membrane of the pharynx, a few filaments 

 pining the superior and external laryngeal nerves. 



2. The superior cervical cardiac nerve (n. cardiacus superior) (Fig. 1131) 

 arises as two or three twigs from the ganglion, with sometimes an additional filament 

 from the association cord between the superior and middle ganglia. It courses down- 

 ward anterior to the longus colli muscle in the posterior part of the carotid sheath, 

 crosses the anterior or the posterior surface of the inferior thyroid artery, and then 

 descends in front of the inferior laryngeal nerve. At the base of the neck the course 

 of the nerve begins to differ on the two sides. 



The right nerve enters the thorax either anterior or posterior to the subclavian 

 artery and accompanies the innominate artery to the aorta, where it enters the deep 

 cardiac plexus, a few fibres passing to the anterior surface of the aorta. On the way 

 down a few twigs join the inferior thyroid artery and with it enter and supply the 

 substance of the thyroid body. 



The left nerve upon entering the thorax joins the common carotid artery, along 

 whose lateral and anterior surfaces it courses to the aorta, upon reaching which it 



