ABSC£SS, CYST, SINUS, FISTULA, AND POLYPUS 63 



of the proximity to large vessels. In this situation it may 

 attain such a size as to interfere with respiration, and even 

 threaten asphyxia. They are also common between the 

 digits, where they sometimes cause great pain and lameness 

 (see Fig. 235). 



Should it be impossible to dissect out the cyst wall, the 

 interior should be freely curetted, and afterwards dressed 

 with pure tincture of iodine. 



An interesting and unusual situation in the spinal column 

 is illustrated by Fig. 209. 



Sinuses. 



By a sinus is understood a wound which has ' pocketed ' 

 or ' burrowed ' a certain depth into the surrounding tissues. 

 It may have more than one opening communicating with 

 the outside, and there may be more than one sinus communi- 

 cating with the same wound. 



Treatment, — The first thing necessary in dealing with a 

 sinuous wound is to ascertain its depth and the exact direc- 

 tion in which it goes. For this purpose a probe, usually 

 made of metal or whalebone, is carefully inserted into the 

 orifice and passed inwards as far as possible. This must be 

 done in a very delicate manner, especially in the case of 

 wounds in the neighbourhood of joints or of any vital 

 organs. One must not forget that it may reveal the presence 

 of a foreign body. Having ascertained the depth, if it is 

 thought desirable to open it up and so make a clean exposed 

 wound, a director (Fig. 39) is inserted, and the whole length 

 laid open by means of a sharp or blunt pointed bistoury, the 

 granulation tissue being scraped away with a Volkmann's 

 spoon. It is sometimes possible to dissect out the whole 

 sinus. 



If, instead of laying the sinus open, it is considered 

 desirable to scrape the interior, this is done by the aid of 

 a curette or Volkmann's spoon (Fig. 40). Frequently the 



