TOPOGRAPHIC AND APPLIED ANATOMY. 

 FIG. 25. The submaxillary and carotid triangles. 



the epiglottis. This mass of fat produces the so-called epiglottic tubercle, which projects into the 

 vestibule of the larynx. It will be seen that this fatty tissue is not particularly adapted for opera- 

 tive procedures. As a result of laryngitis, abscesses occasionally form in this mass of fat, which 

 may be evacuated externally by an incision through the thyrohyoid ligament. The subhyoid 

 region is broadest at its lower boundary, which is formed by the thyroid notch. In the median 

 line there is an inconstant bursa situated between the thyrohyoid membrane and the sternohvoid 

 muscle; it extends upward beneath the hyoid bone and occasionally leads to the development of 

 hygromata. There is also a bursa lower down over the angle of the thyroid cartilage. 



The largest portion of the laryngeal region is taken up anteriorly by the thyroid cartilage, 

 which causes the hard projection (in the male) known as the Adam's apple. The thyroid cartilage 

 is connected to the cricoid cartilage by the tense crico-thyroid ligament (or ligamentum conicum). 

 This is the situation in which the larynx may be most easily opened below the vocal cords. The 

 incision may be carried upward, dividing the thyroid cartilage (thyrotomy), or downward, divid- 

 ing the cricoid cartilage (cricotomy). The small cricothyroid artery, lying upon the cricothyroid 

 ligament, possesses no special surgical importance. A median sagittal section (see Fig. 26) shows 

 that abscesses resulting from perichondritic processes affecting the arytenoid cartilages and the 

 lamina of the cricoid cartilage, which form the posterior wall of the larynx, may rupture anteriorly 

 into the larynx, (producing respiratory disturbances) or posteriorly into the laryngeal portion of 

 the pharynx (causing dysphagia). Perichondritis of the anterior wall of the larynx (the thyroid 

 cartilage and the ring of the cricoid cartilage) may lead to the formation of abscesses which either 

 point anteriorly beneath the skin or rupture into the laryngeal cavity. 



The narrow thyroid region is situated just below the laryngeal region and corresponds to 

 the isthmus of the thyroid gland, which is in relation with the upper tracheal rings and frequently 

 touches the cricoid cartilage. In children the isthmus of the thyroid gland usually extends to a 

 higher level than in adults, but it does not reach beyond the cricoid cartilage; it is also more 

 firmly fixed to the trachea in the child than in the adult. When high tracheotomy is performed, 

 the isthmus must be separated from the trachea by blunt dissection and pushed downward, so 

 that the incision for the introduction of the tracheal tube will not injure the thyroid gland. The 

 performance of this operation is not infrequently complicated by the presence of a middle lobe of 

 the thyroid gland, which often extends up to the hyoid bone. It is situated either exactly in the 

 median line or somewhat to one side. The thyroid gland, covered by the sternothyroid and 

 sternohyoid muscles, extends laterally into the carotid triangle and comes in contact with the 

 lowest portion of the pharynx and the commencement of the esophagus. From the position of the 

 thyroid gland it is clear that thyroid swellings and tumors must lead, first of all, to pressure- 

 symptoms from the trachea with changes in the tracheal cartilage, and then to involvement of the 

 large vessels and nerves of the neck. The inferior laryngeal nerve runs upward behind the thyroid 

 gland between the trachea and the esophagus and should be carefully avoided in the extirpation of 

 goiters, as injuries of this nerve are followed by paralyses of the laryngeal muscles of the same side. 

 The trachea is situated considerably more deeply below than above the thyroid gland. This fact 

 in itself complicates the performance of tracheotomy in this situation (low tracheotomy), and 



