ABDOMINAL INCISIONS. 1409 



falx inguinalis, as well as from the fascia transversalis ; if through the lateral part 

 of the triangle, the lateral- edge of the falx inguinalis curves round the medial 

 side of the neck of the sac. To relieve the constriction at the neck of the sac, 

 in the case of an oblique inguinal hernia, the edge of the knife is directed 

 superiorly and laterally to avoid the inferior epigastric artery, while in a direct 

 hernia the artery is avoided by dividing the constriction in a superior and medial 

 direction. In an oblique inguinal hernia the sac lies within the internal spermatic 

 fascia (fascia propria of the hernia), whereas in a direct hernia the fascia propria 

 is derived froml the fascia transversalis of Hesselbach's triangle. The extra- 

 peritoneal fat which covers the outer surface of the hernial sac is sometimes 

 hypertrophied to such an extent as to amount to a fatty tumour. 



In a large proportion of children, at birth, the vaginal process of peritoneum, 

 which connects the tunica vaginalis testis with the abdominal peritoneum, is still 

 patent, especially on the right side. Should the bowel force its way along the 

 patent process a congenital inguinal hernia arises. In the majority of the cases 

 of congenital inguinal hernia it will be found that the tunica vaginalis testis has 

 been shut off by closure of the lower part of the vaginal process, only the superior 

 part remaining patent and forming the sac of the hernia. 



In the child the persistence of a patent vaginal process can almost invariably 

 be detected by rolling the cord between the finger and thumb ; after the ductus 

 deferens and spermatic vessels have slipped away from one's grasp the edge of the 

 sac can be felt to follow them. In regard to the operation for the cure of inguinal 

 hernia, it should be borne in mind that in the acquired form the hernia produces 

 the sac, whereas in the congenital variety the sac is the cause of the hernia ; it 

 follows, therefore, that in the operation for acquired hernia the closure of the canal 

 is as important as the removal or obliteration of the sac, while in a congenital 

 hernia the most essentia*! part of the operation is the closure of the neck of the 

 sac, and as the muscular and fascial apparatus forming the walls of the canal are 

 often well developed (especially in children), they should be interfered with as 

 little as possible. A patent vaginal process may persist during adult life 

 without any bowel descending into it ; on the other hand, years after birth, bowel 

 may suddenly enter it. In practically all oblique inguinal hernise, which develop 

 suddenly in children as well as in adolescents and young adults, the sac is of 

 congenital origin. 



In the ordinary form of hydrocele the fluid is confined to the tunica vaginalis testis, 

 but when the vaginal portion of the processus vaginalis remains patent, the hydrocele 

 may extend upwards into the inguinal canal, and may or may not communicate with the 

 general peritoneal cavity. In the condition known as encysted hydrocele of the cord the 

 patent funicular process is shut off both from the tunica vaginalis testis and from the 

 peritoneal cavity. 



ABDOMINAL INCISIONS. 



Before proceeding to deal with the abdominal cavity reference must be made 

 to some anatomical points connected with the more typical incisions made by 

 surgeons in opening the abdomen. 



Incisions in the Median Plane. Median line incisions through the linea alba 

 have the advantage of being comparatively bloodless and rapid of execution, of 

 dividing no motor nerves, and of enabling the surgeon to expose a wide area of 

 the abdomen. Unless special precautions are taken, however, they are more liable 

 to be followed by a ventral hernia. 



Above the umbilicus the linea alba is comparatively broad, so that the edges of 

 the recti are separated by a distinct interval, which may be of considerable width 

 1 in obese subjects and multiparous women. Deep to the linea alba is the trans- 

 versalis fascia, which is so thin and adherent that the two structures form 

 practically a single layer. The extraperitoneal fat, which forms a comparatively 

 thick stratum, must not be mistaken for omentum. The peritoneum presents itself 

 as a thin, bluish, semi- transparent membrane. If it is necessary to prolong the incision 

 downwards below the level of the umbilicus, it should skirt its left margin so as to 



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