The sac of the hernia usually lies above and in front of the cord.
Running closely connected with the cord are the veins which go to make up the pampiniform plexus. These veins being close to the cord and the cord itself quite susceptible to pressure it is advisable to pass the needle along near the roof of the inguinal canal and to attain this
end it is well to locate definitely the external ring and to have a distinct knowledge of the exact situation of the upper margin of the ring.
Considerable cellular tissue is found in the inguinal canal so that in passing the needle through the canal should it meet with considerable resistance it has no doubt missed the canal and entered some of the more resistant tissues making up its walls.
The cellular tissue in the canal is to receive the injection of the operator and it will be his object to facilitate the diffusion of the various materials injected so that an extensive formation of connective tissue will be promoted. The plug action of the injection is not alone to be considered for the operator is then likely to throw too much into the canal and with the development of the connective tissue the canal is unduly crowded.
The ill consequences of hyperinjection should not be forgotten. It is the error to which the beginner is most liable.
WHERE THE INJECTION SHOULD BE PLACED.
Some operators have been content to insert a needle over the approximate site of the internal ring and then to force it downward until it lies as close to the internal ring as they can approximate and then to throw in a mass of paraffin sufficient to occlude the canal at this point.
If the needle is inserted about half an inch above the middle of Poupart's ligament it will be over the site of the normal internal ring. After the needle passes through the subcutaneous fat it will be felt to strike the firm fibrinous layers of the external wall of the inguinal canal. After the needle has passed through this firm layer it will enter the loose cellular tissue in the neighborhood of the internal ring. If the injection is diffused over an area of an inch or