4 SURGICAL APPLIED ANATOMY. ichap. i. 



to illustrate this fact in the person of an infant. A 

 midwife attending a woman in labour mistook the 

 scalp of the infant for the membranes, and gashed it 

 with a pair of scissors. Labour pains came on and the 

 head was protruded through the scalp wound, so that 

 the whole vault of the skull was peeled like an orange. 

 The scalp being firmly stretched over the hard 

 cranium beneath, it follows that contused wounds 

 often appear as cleanly cut as are those that have 

 been made by an incision. Such wounds may be 

 compared to the clean cut that may be made in a kid 

 glove when it is tightly stretched over the knuckles, 

 and those parts are sharply rapped. 



The scalp is extremely vascular, and presents there- 

 fore a great resistance to sloughing and gangrenous 

 conditions. Large flaps of a lacerated scalp, even 

 when extensively separated and almost cut off from 

 the rest of the head, are more prone to live than to 

 die. A like flap of skin, separated from other parts 

 of the surface, would most probably perish ; but the 

 scalp has this advantage, that the vessels run practi- 

 cally in the skin itself, or are, at least, in the tissue 

 beyond the aponeurosis (Fig. 1). Thus, when a scalp 

 flap is torn up, it still carries with it a very copious 

 blood supply. Bleeding from these wounds is usually 

 very free, and often difficult to arrest. This depends, not 

 so much upon the number of vessels in the part, as 

 upon the density of the tissue through which these 

 vessels run, the adherence of the outer arterial wall to 

 the scalp structure, and the inability, therefore, of the 

 artery to properly retract when divided. 



For the same reason it is almost impossible to 

 pick up an artery divided in a scalp wound. The 

 bleeding is checked by a hare-lip pin or by pressure. 



In all parts of the body where a dense bone is 

 covered by a comparatively thin layer of soft tissues, 

 sloughing of those tissues is apt to be induced by 



