THE INFERIOR CERVICAL GANGLION. 639 



ieliternal to the superior intercostal artery. Oftentimes it extends on neck of 



front of the neck of the rib, and joins the first ganglion of the 

 ielord in the thorax. Its branches are similar to those of the other 



ganglia. 



it| Connecting branches join the last two cervical nerves. Other Branches to 

 erves accompany the vertebral artery, forming the vertebral plexus nerves and 

 udiround it, and communicating with the cervical nerves. 



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

 orfrom the lower ganglion. It lies beneath the subclavian artery, 

 ir joining in that position the recurrent laryngeal nerve, and enters 

 he thorax to terminate in the deep cardiac plexus behind the arch 

 >n pf the aorta. 

 ir I DIRECTIONS. The student will now observe, so far as they are left, Directions. 



e structures in the upper opening of the thorax, and will then pro- 

 eed to the dissection of the orbit whilst the skull is whole, in the 

 neantinie carefully wrapping up and treating with preservative the 

 mrts left in the neck. 



PARTS IN THE UPPER APERTURE OF THE THORAX (fig. 171, p. 467). Parts in the 

 The relative position of the several parts entering or leaving the thorax 

 thorax by the upper opening may be now observed. 



In the middle line lie the remains of the thymus gland, and the in middle 

 [trachea and oesophagus. In front of the trachea are the lower ends ine ' 

 of the sterno-hyoid and sterno-thyroid muscles with layers of the 

 cervical fascia, and the inferior thyroid veins ; and behind the gullet 

 and windpipe are the longi colli muscles. Between the two tubes 

 is the recurrent nerve on the left side. 



On each side the dome of the pleura and the apex of the lung q n each 

 project into the neck ; and in the interval between the pleura and side: 

 the trachea and oesophagus, are placed the vessels and nerves passing 

 between the thorax and the neck. Most anteriorly on both sides partly the 

 lie the innominate vein, the phrenic nerve, and the internal mam- SJthSdes, 

 mary artery ; but the vessels and nerves next met with are different and partly 

 on the two sides : On the right side are the innominate artery, dl 

 with the vagus, the cardiac nerves and the right lymphatic duct. 

 On the left side are the left vagus, the left common carotid artery, 

 the thoracic duct and the left subclavian artery with the cardiac 

 nerves. Lastly, altogether behind on each side are part of the first 

 dorsal nerve, the cord of the sympathetic, and the superior intercostal 

 artery. 



SECTION X. 



DISSECTION OF THE ORBIT. 



Position. In the examination of this cavity the head is to be Position of 

 placed in the same position as for the dissection of the sinuses of the tnehead - 

 base of the skull. 



Dissection. The cotton- wool beneath the eyelids should be taken How to open 

 away, and the bone forming the roof of the orbit may be removed in 



