CERVICAL GANGLIA OF SYMPATHETIC. 117 



two pieces, which enter the canal for the carotid, one on each side of that 

 vessel : and are continued to the eyeball and the pia mater of the brain, 

 forming secondary plexuses on the ophthalmic and cerebral arteries. In 

 the carotid canal communications are formed with the tympanic nerve (p. 

 Ill) and with the spheno-palatine ganglion (p. 141) ; with the former near 

 the lower, and with the latter near the upper opening of the canal. The 

 communications and plexuses which these nerves form in their course to 

 the base of the brain are described at p. 33. 



The pharyngeal nerves pass inwards to the side of the pharynx, where 

 they join with other branches of the cranial nerves in the pharyngeal 

 plexus (p. 113). 



Cardiac nerves enter the thorax to join in the plexuses of the heart. 

 There are three cardiac nerves on each side, viz., superior, middle, and 

 inferior, each taking its name from the ganglion of which it is an offset. 



The superior cardiac nerve (superficial) of the right side courses behind 

 the sheath of the carotid vessels, and enters the thorax beneath the sub- 

 clavian artery. In the neck the nerve is connected with the cardiac 

 branch of the vagus, with the external laryngeal, and with the recurrent 

 nerve. In some bodies it ends by joining one of the other cardiac nerves. 



The MIDDLE CERVICAL GANGLION (gang, thyroideum) is of small size, 

 and is situate opposite the fifth cervical vertebra, usually on or near the 

 inferior thyroid artery. It has a roundish shape, and lies beneath the 

 great vessels. Its branches are the following: 



* Connecting branches with the spinal nerves sink between the borders 

 of the longus colli and anterior scalenus, to join the fifth and sixth cervi- 

 cal nerves. 



Branches for Distribution. These consist of nerves to the thyroid 

 body, together with the middle cardiac nerve. 



The thyroid branches ramify around the inferior thyroid artery, and 

 end in the thyroid body ; they join the external and recurrent laryngeal 

 nerves. 



The middle or great cardiac nerve descends to the thorax across the 

 subclavian artery ; its termination in the cardiac plexus will be learnt in 

 the chest. In the neek it communicates with the upper cardiac and re- 

 current laryngeal nerves. 



The INFERIOR CERVICAL GANGLION is of large size but irregular in 

 shape, and occupies the interval between the first rib and the lateral mass 

 of the last cervical vertebra, its position being internal to the superior 

 intercostal artery. Oftentimes it extends in front of the neck of the rib, 

 and joins the first swelling of the knotted cord in the thorax. Its branches 

 are similar to those of the other two ganglia. 



One or two branches surround the trunk of the subclavian artery, and 

 supply filaments to that bloodvessel. 



* Connecting branches join the last two cervical nerves. Other nerves 

 accompany the vertebral artery, forming a plexus vertebral, around it, 

 and communicate with the spinal nerves as high as the fourth. 



Only one branch for distribution, the inferior cardiac nerve, issues from 

 the lower ganglion. It lies beneath the subclavian artery, joining in that 

 position the recurrent laryngeal nerve, and enters the thorax to terminate 

 in the deep cardiac plexus behind the arch of the aorta. 



Directions. The student now proceeds to dissect the left side of the 

 neck, but the remains of the right half should be carefully preserved during 

 the time occupied in the examination of the left half. 



