338 HEAD AND NECK 



upon the lateral aspect of the cricoid cartilage, immediately 

 posterior to the crico-thyreoid joint. There it is joined by 

 the communicating twig from the internal laryngeal nerve, and 

 almost immediately afterwards it divides into two branches. 

 The forger of the two proceeds upwards, under cover of the 

 lamina of the thyreoid cartilage, and breaks up into filaments 

 which supply the lateral crico-arytsenoid, the thyreo-arytsenoid, 

 the vocalis and the thyreo-epiglottic muscles; the smaller or 

 posterior branch inclines upwards and backwards, upon the 

 posterior aspect of the cricoid cartilage, and under cover of 

 the posterior crico-arytsenoid muscle. It supplies twigs to 

 that muscle, and is then continued onwards to end in the 

 arytaenoid muscles. 



The inferior laryngeal nerve is, therefore, the motor nerve 

 of the larynx. It supplies all the muscles, with the exception 

 of the crico-thyreoid, which obtains its nerve-supply from the 

 external laryngeal. The inferior laryngeal nerve, however, 

 contains a few sensory fibres also. Those it gives to the 

 mucous membrane of the larynx below the rima glottidis. 



Laryngeal Arteries. The superior laryngeal artery, a 

 branch of the superior thyreoid, accompanies the internal 

 laryngeal nerve ; the inferior laryngeal artery, which springs 

 from the inferior thyreoid, accompanies the inferior laryngeal 

 nerve. The two vessels ramify in the laryngeal wall and 

 supply the mucous membrane, glands, and muscles. 



Laryngeal Cartilages and Joints. The cartilages which 

 constitute the skeleton of the larynx and give support to its 

 wall are the following : 



i. Thyreoid, 1 4 _ Arytgenoid> > 



3. Carnage of the \ sin le ' |- Consulate, paired, 



epiglottis, J 6 " Cuneiform, 



They are connected by certain ligaments. 



Dissection. The mucous membrane and muscles must be 

 carefully removed from the cartilages, and the ligaments must 

 be defined. Exercise great caution while cleaning the arytaenoid 

 cartilages and the corniculate cartilages, in order that the latter 

 may not be injured. 



Cartilage Epiglottica. The epiglottic cartilage is a thin, 

 leaf-like lamina of yellow nbro-cartilage which is placed posterior 

 to the tongue and the body of the hyoid bone, and anterior 

 to the upper aperture of the larynx. When divested of the 



