NERVI ACCELERANTES 65 



VII. Detach the tracheal cannula from the flexible tube which connects it Obs. 40. 

 with the ventilation-nozzle on operation table and quickly insert a short length Q'^^'^ity ^^^ *^*- 

 (e.g. 30 cm.) of suitably sized rubber tube, joining tracheal cannula to flexible tube 



from ventilation-nozzle, rotating the nozzle in the table-top so that it is directed 

 to side on which kymograph stands. The junction between preparation and 

 ' blower ' having been thus lengthened, place the small board (provided) under 

 the preparation and lift it somewhat off the table without disturbing the 

 connexion of carotid with kymograph, while your colleague moves the table 

 aside from under the board. Keeping the carotid of the preparation at its 

 previous level, and while your colleague takes the other end of the board and 

 prevents the preparation from slipping, tilt the board until it and the 

 preparation are nearly vertical, the neck-stump retaining its old level in regard 

 to manometer, the trunk and limbs being below it, the ' feet-down ' position. 

 Observe the effect on the carotid pressure. After a minute restore the board 

 and preparation to their former position. Replace it on the table. Detach the 

 extra length of respiration-tubing, and rejoin the tracheal tube to the ' blower '- 

 nozzle as before. 



The kymographic part of the exercise is now complete. 



VIII. Turn to the neck-stump of the preparation. Observe the epiglottis Obs. 41. 

 and by drawing it forward bring the glottis and vocal cords into view. The i^ec^^rent 

 latter exhibit no movement because the vagus trunks have been severed by the the vocal cords, 

 decapitation, and the laryngeal nerves are branches of these. 



IX. Expose the trachea above the tracheal cannula. Note a small nerve 

 running along its ventrolateral aspect, on either side ; this is recurrent laryngeal. 

 Dissect it carefully for about 15 mm. Ligate it at the posterior end of the 

 portion you have dissected up. Cut it posterior to the ligature. Lift the 

 freed portion by the ligature. Faradize the distal end. Observe the move- 

 ment of the corresponding vocal cord. 



ANNOTATION 



Obs. 39. The quickening of the heart The operative procedure followed here for 



obtained by stimulating the sympathetic reachmg the stellate ganglion is that intro- 



nerve-branches passing ventrally from gang- duced by H. K. Anderson, 1904 {Jnl of 



lion stellatum was discovered (in the dog) by Physiol vol. xxxi ; Froc. Physiol Soc. p. 



the Russian physiologists M. and E, de Cyon xxxi). 



in 1866 {Centralblf. Med. Wiss.) ; they gave Ohs. 40. See L. Hill, 1895 {Jnl of Physiol 



the name nervi accelerantes to these branches, vol. xviii, p. 15) ; also Hill on the Circulation, 



E. de Cyon was the discoverer also of the Sehafer's Texthh of Physiol vol. ii, p. 91, 



nervus depressor, 1870 (see later, exerc. XIV). 1900. 



