90 METHODS OF DIVIDING TISSUES. 



For holding the edges of wounds apart sharp hooks or retractors 

 are employed (Figs. 77 to 79). 



When operating in certain cases other methods of dividing tissues 

 are sometimes resorted to, such as tearing, blunt dissection, linear 

 crushing by the ecraseur, the use of the elastic ligature, and the 

 cautery. 



Tearing is chiefly used in removing sharply defined tumours 

 which are only slightly adherent to neighbouring tissues. The skin 

 having been incised the growth is isolated by pushing aside or tearing 

 through the surrounding tissues with the fingers, or by a combination 

 of these methods. Although valuable on account of not endangering 

 important vessels or nerve trunks, this method gives very acute 

 pain where the parts are richly supplied with nerves, and is inapplic- 

 able to such new growths as spread by the lymphatics, inasmuch as 

 extirpation is incomplete and secondary tumours soon grow. 



When larger tracts of tissue are in question the fingers of both 

 hands may be employed. Although wounds so made are really 

 torn wounds, they bleed relatively little, and often heal very rapidly. 



Fig. 101.— Director. 



For blunt dissection the end of a director or a small spatula may 

 be used. The movement is of a stabbing or thrusting character, 

 the point tearing through the connective tissue and isolating the 

 part without danger of haemorrhage. This method is excellent when 

 operating in dangerous regions. It is particularly useful for isolating 

 vessels, as in ligaturing the jugular vein or carotid artery. The 

 wounds produced by blunt dissection heal almost as quickly as those 

 made with the knife. 



The Ecraseur. The ecraseur (Figs. 102 to 104), is still much 

 employed in veterinary practice. It crushes soft tissues, though to 

 some extent it also acts like a saw. Mucous membranes, connective 

 and fibrous tissues, muscles, vessels, neoplasms, are all cut without 

 haemorrhage if the instrument is worked sufficiently slowly. Its 

 action is especially remarkable in vessels : the middle and internal 

 coats rupture and retract whilst the external coat is stretched and 

 twisted in such a way as to effect almost complete closure. Pain, 

 which is very severe as compression begins, diminishes with com- 

 mencing section. As a rule the surface of section cicatrises less 



