370 DISSECTION OF THE EABBIT. 



lateral depressions of the mucous membrane of the 

 inner surface of the larynx. 



6. The vocal cords are a pair of folds of mucous membrane, 



strengthened by elastic ligaments, and forming the 

 posterior lips of the ventricles. They are attached 

 dorsally to the arytenoids, and at their ventral ends 

 to the thyroid cartilage. It is by their vibration 

 that the ' voice ' is produced. 



7. The glottis is the median slit between the vocal cords, 



through which the air passes to and from the lungs. 



8. The false vocal cords are folds of mucous membrane 



similar to the vocal cords : they form the anterior 

 boundaries of the ventricles. 



VIII. THE SYMPATHETIC NEEVOUS SYSTEM. 



The sympathetic nervous system consists of a double chain 

 of ganglia, lying at the sides of and ventral to the spiaal 

 column ; and of the commissural cords connecting them with 

 one another, and with the spinal nerves. From the gangha 

 nerves are given oft', some of which follow the arteries, and 

 end in their muscular coats, while others unite to form 

 plexuses, with gangUonic enlargements, in the thorax and 

 abdomen, in relation with the heart and the abdominal viscera. 



The dissection of the sympathetic nervous system, which 

 is not easy, is best performed on a freshly killed rabbit. 



A. The gangliated sympathetic cords are a pair of longi- 

 tudinal nerve trunks running alongside the vertebral column, 

 and linking together the series of ganglia through which the 

 sympathetic system communicates with the spinal and cranial 



nerves. 



1. The cervical sympathetic nerve has already been seen 

 in the dissection of the neck (p. 368). It runs along- 

 side the depressor nerve and close to the trachea, 

 and presents three ganglionic enlargements. 



