81 



EXERCISE XIII 



KEFLEXES OF PHARYNX AND LARYNX. GRAPHIC OF RESPIRATORY 

 MOVEMENT OF CHEST AND ABDOMEN; INFLUENCE OF DEGLUTITION 

 UPON THEM. INFLUENCE OF SEVERANCE AND OF STIMULATION OF 

 THE VAGUS ON RESPIRATORY RHYTHM. 



I. The decerebrate preparation provided for you is supported by a 

 vertical standard so that pharynx is well above rest of carcase. See 

 that it rests in a position allowing freedom for the chest movements. 



II. Have in readiness, in addition to the ordinary apparatus, the 

 following : 



(1) Small laryngoscope mirror on wire handle, for insertion against 

 the fauces. If your working-place is in a good light the large laryngoscope 

 mirror for wearing on the forehead is not required, the pharynx being 

 open to inspection without it in the decerebrate preparation ; (2) large 

 watch-glasses containing (a) water, (b) 25 per cent, alcohol, (c) olive oil ; (3) a 

 fountain-pen filler with the usual rubber cap, and marked at a point indicating 

 •5 c.c. of content ; (4) a long bristle mounted on a penholder ; (5) the 

 wire stethograph (text-fig. 30). 



See that the kymograph is arranged for carrying the recording-paper 

 slowly ; see that the paper travels from right to left when viewed from 

 in front. 



III. Clear the faucial entrance to pharynx of mucus with a moist Obs. 60. 

 swab. Turn preparation so that light falls into faucial entrance. The i^^spectio^ o*" 

 head should not be flexed, but rather extended on neck. Observe soft movements of 

 palate ; draw tongue forward ; observe epiglottis, the free end of which larynx. 



is probably in its normal position, i. e. tucked up above edge of velum 

 palati. Stitch a beaded thread to tip of epiglottis. Keep tongue drawn 

 forward by clip-weight to tip. Observe the vocal cords by resting the warmed 

 laryngoscope mirror against the back of the soft palate : note the vocal 

 cords and their respiratory movements ; they move wider apart at each 

 inspiration. 



IV. Place 1 c.c. of water on middle of dorsum of tongue. No response. Obs. 61. 

 Place 1 c.c. of water on tongue farther back, so that it runs into the glosso- ^^^^^ ^wai- 

 epiglottidean pockets. Swallowing follows. Note that inspiration is inhibited °^^^^' 



at each swallow. 



2131 M 



