134 SURGICAL APPLIED ANATOMY. [Chap. ix. 



adds much to the difficulties of tracheotomy. In 

 this procedure the windpipe is opened in the middle 

 line by cutting two or three of its rings above, 

 below, or through the isthmus of the thyroid gland. 

 Since the trachea, as it descends, lies farther from the 

 surface, and comes in relation with more and more 

 important structures, it is obvious that, other things 

 being equal, the higher in the neck the operation can 

 be done the better. The length of trachea in the 

 neck is not so considerable as may at first appear, 

 and, according to Holden, not more than some 7 or 8 

 of the tracheal rings (which number 16 to 20 in all) 

 are usually to be found above the sternum. The 

 distance between the cricoid cartilage and the sternal 

 notch varies greatly, and depends upon the length of 

 the neck, the age of the patient, and the position of 

 the head. If 2 inches of trachea are exposed above 

 the sternum when the head rests easily upon the 

 spine, then in full extension of the head some f of 

 an inch more of the windpipe will, as it were, be 

 drawn up into the neck. According to Tillaux, the 

 average full distance between the cricoid cartilage and 

 the sternum is, in the adult, about 2| inches (7 cm.). 

 The full distance in a child between three and five 

 years is about \\ inches (4 cm.), in a child between 

 six and seven about 2 inches (5 cm.), and in children 

 between eight and ten years about 2^ inches (6 cm.). 

 As may be imagined, the dimensions of the trachea 

 on section vary greatly at different ages, and even in 

 different individuals of the same age. This leads to 

 the question as to the proper diameter of tracheotomy 

 tubes. Guersant, who has paid much attention to 

 this matter, says that the diameter of the tubes should 

 run from 6 mm. to 15 mm.* The tubes with a 

 diameter of from 12 mm. to 15 mm. are for adults. 



* The reader may be reminded that 12 mm. = about half an 

 inch, and 6 mm., therefore, = about a quarter of an inch. 



