THE KIDNEYS. 429 



the erector spinse muscle and passes downward and forward almost or quite parallel 

 to the twelfth rib, toward the anterior extremity of the crest of the ilium. Mayo 

 Robson {Lancet, May 14, 1898) made an incision from the inner edge of the anterior 

 superior spine of the ilium to the tip of the last rib. The fibres of the external 

 oblique were then split and retracted. Then the fibres of the internal oblique and 

 transversalis were split, and retracted in the opposite direction. For this method it 

 is claimed that no muscles, nerves, or vessels are divided, and the patient can be 

 operated on while lying" on the back. (Consult the Lumbar Muscles, page 392 ; 

 Fascia, page 393; and Incisions, page 395). 



Nerves. The nerves to be avoided in making lumbar incisions are the last 

 thoracic, the iliohypogastric, and the ilio-inguinal. The last thoracic nerve, ac- 

 companied by the first lumbar artery, runs parallel to the last rib a short distance 

 below 1.25 cm. ($4 in.) and thence pursues a direct course toward a midpoint 

 between the umbilicus and top of the pubes. It emerges from beneath the external 

 arcuate ligament about the middle of the kidney, crossing the quadratus lumborum, 

 pierces the tendon of the transversalis muscle and runs between it and the internal 

 oblique to pierce the sheath of the rectus and be distributed to the skin midway 

 between the umbilicus and top of pubes and supply the pyramidalis muscle. This 

 portion of the nerve will be injured only if the incision is carried up to the twelfth 

 rib. When it is about opposite the tip of the eleventh rib it gives off a lateral (or 

 iliac) branch which goes downward and slightly forward to pierce the internal and 

 external oblique muscles above the crest of the ilium, about 5 cm. (2 in.) posterior 

 to the anterior superior spine. This branch will be cut in making the incision, but 

 it is only a sensory nerve, not a motor. 



The iliohypogastric and iUo-inguinal nerves, from the first lumbar, come out 

 together from beneath the psoas muscle opposite the lower third of the kidney, 

 cross the quadratus lumborum, and pass downward and forward toward the crest of 

 the ilium a little in front of its middle. The iliohypogastric is above the ilio-inguinal, 

 and, piercing the transversalis muscle, divides into the hypogastric and iliac branches. 

 The former pierces the external oblique 2. 5 cm. ( i in. ) above and a little to the 

 outer side of the external inguinal ring. The latter goes over the crest of the ilium 

 to the gluteal region. The ilio-inguinal pierces the transversalis and enters the 

 inguinal canal to go to the genitals and anterior inner portion of the thigh. 



These nerves will probably be seen in making the longitudinal incision, toward 

 its upper portion, they should be pulled aside. In. the oblique incision they will be 

 posterior and not visible. 



Pleura. The pleura reaches the lower border of the posterior portion of the 

 twelfth rib; it crosses the rib posterior to its middle, if the rib is of normal length, to 

 pass to the eleventh rib. Therefore, to avoid the pleura the incision must not touch 

 the twelfth rib posterior to its middle. One must not forget that the ribs are irregular 

 in number and especially in length. It is necessary to identify the twelfth rib, this 

 may be extremely difficult, and unless the greatest care is used a mistake is liable to 

 occur. If the eleventh rib is mistaken for the twelfth the pleura comes so much 

 farther forward that it is almost certain to be wounded, as has once occurred, produc- 

 ing a fatal result. The ribs may be counted down from the second at the angle of 

 the sternum (Ludwig), remembering the possibility of there being, as we have seen, 

 fourteen ribs on a side, or thirteen, or only eleven. The twelfth rib is frequently so 

 short as to be completely concealed by the muscles; in that case only one floating rib 

 would be seen. 



If it is necessary to excise a rib, begin at its anterior extremity, where it is not 

 in contact with the pleura, and scrape off the periosteum from before backward. 



Delivering the Kidney. After getting through the abdominal wall one 

 comes down on the fat surrounding the kidney and its capsules. The kidney is to 

 be felt inward and backward toward the spine. Having been located by touch the 

 perirenal fascia and the fatty capsule are to be opened and the kidney pushed and 

 lifted into the wound. Do not go anterior, because there the colon or peritoneum 

 may bulge forward. Once freed from its fatty capsule the normal-sized kidney is 

 sufficiently movable to be lifted clear out of the wound onto the surface. If it is too 

 large the wound must be enlarged downward. Incisions into the kidney substance 



