142 



ADVANCED LESSONS IN PRACTICAL PHYSIOLOGY 



Temporarily occlude the rubber tube attached to the tracheal cannula, 

 producing dyspnea and thereby rendering these variations more con- 

 spicuous. 



Stimulate the lining of the larynx with a tuft of cotton fastened to 

 a wooden stick. Note the resultant inhibition of respiration and the 

 forced efforts at expiration (act of coughing). Compare these effects 



FIG. 89. LATERAL VIEW OF LARYNX 

 TO ILLUSTRATE THE ACTION OF THE CRICO- 

 THYROID MUSCLE. 



H, Hyoid bone; M, thyrohyoid mem- 

 branes; PA, pomum Adami; T, thyroid 

 cartilage; C, cricoid cartilage; Tr, trachea; 

 CT, cricpthyroid muscle; P, vertical plate 

 of cricoid with (A) arytenoid cartilages 

 placed transversely upon its articulating 

 processes; VC, vocal cords; R, imaginary 

 center of rotation of cricoid. When crico- 

 thyroid muscle contracts, T and C are 

 brought closer together, while A is forced 

 away from PA. 



Er 



FIG. 90. THE INNERVATION OF THE 

 LARYNX (POSTERIOR VIEW; ONE SIDE). 



B, Base of tongue; E, epiglottis; A, 

 arytenoid muscles; CA, crico-arytenoid 

 muscle; T, trachea; V, vagus nerve; SL, 

 superior laryngeal nerve; J and O, its inner 

 and outer branches; JL, inferior laryngeal 

 nerve; Br, vagal fibers innervating bron- 

 chial musculature. 



with tfyose commonly observed after the entrance of a foreign body into 

 the larynx. 



5. The Superior Laryngeal Nerve. Place the intact superior laryn- 

 geal nerve in shielded electrodes and stimulate very briefly. Analyze 

 the effect produced thereby upon (a) the general character of the 

 respiratory movements, and (b) the action of the laryngeal muscles. 



Divide the superior laryngeal nerve between two ligatures. Stimu- 

 late its distal as well as its central end repeatedly, analyzing the effects 

 produced in each case. 



