124 



APPLIED ANATOMY. 



between the buccopharyngeal fascia and prevertebral fascia. Its spread upward is 

 limited by the skull; laterally it is limited by the sheath of the carotid vessels; hence 

 it passes downward behind the oesophagus and may enter the posterior mediastinum. 

 Foreign bodies may become lodged at the lower end of the pharynx and at the 

 beginning of the oesophagus. As this is about 15 cm. (6 in.) from the teeth, it is 

 beyond the reach of the ringer. Luckily, this is below the opening of the larynx and 

 the need for immediate relief is not so urgent. 



THE LARYNX. 



The larynx extends from the top of the epiglottis to the lower edge of the 

 cricoid cartilage. It is composed of the three large cartilages epiglottis, thyroid, 

 and cricoid and three pairs of small ones the arytenoids, the cornicidce laryngis 

 or cartilages of Santorini, and the cuneiform or cartilages of Wrisberg. 



The position of the larynx in relation to the spine varies according to age. In 

 the infant it lies opposite the second, third, and fourth cervical vertebrae; in the adult 



Epiglottis 



Greater horn of hyoid bone 



Body of hyoid bone 



Superior cornu 



Opening for superior laryngeal 



nerve 



Thyrohyoid membrane 

 Thyroid cartilage 



Inferior cornu 

 Cricothyroid membrane 

 Cricoid cartilage 



Trachea 



FIG. 157. Anterior view of hyoid bone and larynx. 



it lies opposite the fourth, fifth, and sixth. The larynx being loosely attached varies 

 in relation to the vertebrae according to the position of the head, so that the anterior 

 portion of the cricoid cartilage may be opposite the seventh cervical vertebra in some 

 positions. 



Epiglottis. Usually the tip of the epiglottis lies lower than the dorsum of the 

 tongue, so that looking into the mouth it is not seen; it may, however, be brought 

 into view by depressing the base of the tongue and drawing it forward with a long 

 tongue depressor. As the epiglottis rises above the level of the hyoid bone, a cut- 

 throat wound passing above that bone may cut its tip entirely off. In viewing the 

 epiglottis from above downward it is seen to project somewhat backward in its middle. 

 This is visible in the laryngoscopic mirror and is called the cushion of the epiglottis. 



Running forward from the epiglottis to the base and the sides of the tongue are 

 three folds of mucous membrane, one median and two lateral, called the glosso- 

 epiglottic folds. These form four fossae; those on each side of the median line are 

 called the valleculce. In these fossae foreign bodies, such as fish-bones, etc. , may 

 become lodged. They are readily seen by the laryngoscopic mirror. 



