SALIVARY SECRETION 77 



Follow the lingual nerve beyond its crossing over the ducts distally for 

 15 mm. It runs a wavy course which straightens on protracting the tongue 

 by a clip-weight. Ligate the nerve-twigs as far distal as you can. Sever 

 distal to the ligature ; lifting the central stump with the thread, free it for 

 1 cm. Drawing the tongue forward and to the left with a clip-weight, dry ' 

 the mucosa with a cotton-wool pledget. Faradize the central stump of 

 lingualis nerve with the coil at about 12 cm. on the scale while your colleague 

 observes the mucous membrane to the right side and under the tongue. The 

 appearance of saliva as a bead will reveal the openings of the ducts in the 

 mucosa. Insert cannula {v. infra, § V) and repeat ; note flow. Take off the 

 clip-weight retracting digastric muscle ; note that the muscle contracts on 

 stimulation of central end of lingualis. The contraction is part of the reflex of 

 opening of the mouth which lingualis sometimes causes.] 



V. Note that the lingualis nerve, as traced in the distal direction along Obs. 55. 

 its course, gives off, proximal to crossing the ducts, two lateral branches actkm°7 d 

 (PI. VI, fig. 2) ; one, the larger, turns forward, the other, much smaller, tympani. 

 a delicate filament sometimes difficult to see, leaves the posterior edge of 

 lingualis to pass to the ducts and run along them aborally. This latter is 

 the corda tympani, the secretory nerve to the submaxillary gland. Ligate the 

 lingualis as far proximally as you can. Repeat the faradization of it as before 

 (in next preceding paragraph). Observe result. 



Sever lingualis central to the ligature, and lifting by the ligature the 

 distal clump thus made, free it by careful dissection with fine scissors, working 

 towards its crossing of the ducts, but stopping short of the point where the 

 corda tympani leaves it, usually about 4 mm. from the ducts. 



Under the ducts, as far forward as possible, pass a fine ligature well 

 anterior to the place of crossing of the ducts by lingualis nerve. Tie the ligature 

 tight. Have the duct cannula partly filled with saline solution ready to hand. 

 It is not a matter of importance if some air-bubbles be in the cannula ; the flow 

 of saliva will later soon expel them. See, however, before inserting the 

 cannula that it is patent ; a little blood may get into the fine capillary end 

 and clot there. Ascertain that it is really patent, e. g. by blowing through it 

 into your saline. Lifting the tied ligature on the ducts with the left hand, cut 

 an oblique opening in one of the ducts about half through it, 3 mm. or so 

 behind, i. e. on the gland side of, the ligature. It does not matter which of the 

 ducts you choose ; the glands of both are supplied by corda tympani. If one 

 of the ducts be obviously the larger choose that. Faradize the stump of 

 lingualis prepared proximal to its place of crossing the ducts, the coil being 

 about 15 cm. on the scale and the faradization lasting about 5". A bead of 



