534 SYMPATHETIC NERVE. CERVICAL GANGLIA. 



The trunk of the Sympathetic Nerve descends, on the front of 

 the neck, from this ganglion, as has been already stated. In 

 its course it receives very small twigs from the fourth and fifth 

 cervical nerves, and sends some very small twigs which appear 

 to go to the oesophagus, and some which unite to the laryngeal 

 nerve and go to the thyroid gland. Some twigs which are 

 larger proceed from it into* the thorax, and go to the cardiac 

 plexus hereafter to be described. 



Opposite to the interval between the fifth and sixth cervical 

 vertebrae it forms another ganglion, of an irregular shape, much 

 smaller than the first. This ganglion, in different subjects, 

 differs in size as well as in several other respects. Sometimes 

 it is entirely wanting, and sometimes it is doubled. It is denom- 

 inated the Middle Cervical or Thyroid Ganglion. When the 

 fourth, fifth, and sixth cervical nerves do not send ramifications 

 to the sympathetic nerve, this ganglion receives twigs from 

 them. 



The Middle Cervical, or Thyroid Ganglion sends many 

 ramifications downwards. Some of them enter the thorax 

 and contribute to the formation of the Cardiac Plexus ; others 

 accompany the inferior thyroid artery, and, with twigs from 

 the recurrent nerve, form a plexus which extends towards the 

 thyroid gland. Some proceed downwards before, and others 

 behind, the subclavian artery, to the next ganglion ; among 

 them is generally one which may be regarded as the trunk of 

 the Sympathetic. 



This third Ganglion is denominated the Inferior Cervical, 

 or the First Thoracic. It is almost constantly found in the 

 same situation, viz. between the transverse process of the last 

 cervical vertebra and the head of the first rib, and is partly 

 covered by the origin of the vertebral artery. It is generally 

 larger than the middle ganglion. It receives branches from 

 the sixth and seventh cervical, and the two first dorsal nerves. 

 Ramifications pass from it to the par vagum and recurrent 

 nerve, and also to the cardiac and pulmonary plexus. 



From this ganglion the Sympathetic Nerve proceeds down- 

 wards on the side of the spine, as will be described hereafter. 



