THE NECK. 127 



Diseases of the Larynx. Syphilis affects the larynx and produces ulcers. 

 These may involve almost any portion but usually they are anterior, involving the 

 epiglottis. They are often associated with syphilitic manifestations in the mouth. 

 Tuberculosis affects the posterior portion of the larynx and the bulb-like swellings of 

 the arytenoids are almost pathognomonic. Ulcers when they occur are most marked 

 posteriorly. This affection is associated with a blanching of the mucous membrane 

 of the mouth and the presence of a white frothy mucus, which will lead the laryn- 

 gologist to suspect the existence of the disease before a view of the larynx is obtained. 



Laryngitis of a simple nature produces a reddening of the cords and a swelling 

 of the membrane generally. 



In oedema of the larynx, the serous effusion puffs up the loose mucous membrane, 

 particularly of the aryepiglottic folds and epiglottis. 



Tumors both benign and malignant affect the larynx and can at times be seen to 

 arise from the vocal cords. 



Paralysis of the muscles is most frequent from interference with the recurrent 



Epiglottis 



Plica ventricularis 

 (false vocal cord) 



Ventriculus laryngis 



Plica vocalis (true vocal cord) 



Tuberculum Cuneiform! 

 (Wrisberg) 



Tuberculum corniculatum 

 (Santorini) 



FIG. 160. View of the larynx as seen in the laryngeal mirror. 



laryngeal nerve. This nerve supplies the abductor muscles and when paralyzed the 

 cords tend to fall together. The nerve may be injured in operations on the neck or 

 involved in cancer of the thyroid gland, or oesophagus, or in aneurisms. If one cord 

 is paralyzed, the voice is lost temporarily, and when it returns, it is changed in char- 

 acter. Paralysis of both nerves does not cause entire loss of voice because the cords 

 fall together, but may induce suffocative symptoms ending in 'death. 



THE NECK. 



The neck supports the head. It is a pedestal for the head, and is long in pro- 

 portion to its thickness; the apparent object of this being to elevate the head and 

 allow it to be moved freely in different directions. The animal is thus better enabled 

 to discover its enemies and to guard itself against them. 



The various structures of the neck are mostly long, running between the head 

 above and the trunk below. This is the case with the spine, the air- and food-pas- 

 sages, the blood-vessels, nerves, and even some muscles, as the sternomastoid and 

 trapezius. The shorter structures are either the component parts of the longer 

 ones, as the vertebrae of the spine and the rings of the trachea, or are separate 

 organs like the larynx, thyroid, and submaxillary glands. The presence of these 

 latter organs is not dependent on the length of the neck as is that of the others. In 

 the frog, which practically has no neck, the head being placed directly on the trunk, 

 there still exist both larynx and thyroid gland. In the singing birds the vocal 

 organ or syrinx is placed in the chest at the bifurcation of the trachea. As regards 

 the cervical spine, blood-vessels, air- and food-passages, and muscles, these evidently 

 are proportionate to the length of the neck. In the batrachians or frogs there is but 

 a single cervical vertebra; in the swan there are twenty-five cervical vertebrae, and in 

 the fishes none. In man of course the number of cervical vertebrae remains the same, 



