376 DISSECTION OF THE RABBIT. 



the neck, lying alongside the trachea, and 

 dorsal to the carotid artery, or slightly to its 

 inner side. It supplies almost all the muscles 

 of the larynx. 



On the left side, the nerve is not given off 

 until after the pneumogastric has entered the 

 thorax. It loops round the ductus arteriosus, 

 and then runs forwards along the neck to the 

 larynx (see fig. 65). 



Find the nerve, as it loops round the subclavian artery, or 

 on the left side the ductus arteriosus and arch of the aorta ; 

 and follow it forwards along the neck to the larynx. 



The curious course of the recurrent laryngeal 

 nerves is explained by the shifting backwards 

 of the heart which occurs during development. 

 As this shifting involves the roots of the great 

 vessels, these nerves, which are originally straight, 

 become pulled out into loops. 



c. Branches of the pneumogastric to the heart, lungs, 

 and oesophagus. These are of small size, and 

 are given off in the thorax : the cardiac branches 

 end in a plexus, lying between the roots of the 

 aorta and pulmonary artery. 



Turn the lungs and heart over to one side : follow the 

 pneumogastric backwards through the thorax, alongside the 

 cesophagus, and trace out its branches. 



4. The cervical sympathetic nerve lies alongside the 

 trachea, to the inner side of the carotid artery, 

 and close to the pneumogastric and depressor 

 nerves. 



About the level of the angle of the jaw it 

 has a small oval swelling, the anterior cervical 

 ganglion, and at the posterior end of the neck, 

 a short distance in front of the subclavian 

 artery, there is a similar swelling, the middle 

 cervical ganglion. In the thorax this sympa- 



