118 EXERCISE XIX 



III. Operation. The operation resembles somewhat that of exerc. XVIII. 

 The same structures on the front and at the back of the thigh are exposed in 

 both, but in the present exercise the femoral nerve, instead of being cut as 

 a whole, has its branch to the quadriceps femoris muscle left uncut, while 

 conversely, instead of the peroneal division of the sciatic nerve being 

 separated and left uncut, the whole sciatic trunk, with its combined peroneal 

 and popliteal divisions, is cut and treated as one nerve. In this exercise, as in 

 the last, the hamstring branch of the sciatic is severed . 



a. Expose the left femoral nerve at its exit from psoas as in the previous 

 exercise (XVIII, 3, see PI. IX, fig. 6). Follow the nerve up into the psoas, 

 also for a short distance below that muscle. The nerve will be seen to consist 

 of three divisions (PL IX, fig. 6), a small lateral one which branches off to 

 supply the sartorius muscle, a medial one which is the saphenous nerve, and 

 a large main division between the other two ; this last is the nerve of 

 quadriceps extensor. Sever the two former and leave the latter intact. 

 Sever the ilio-psoas muscle completely across ; to do so use the small scissors, 

 snipping it through piecemeal about the level of Poupart's ligament. 



[Repeat the same operation on the right femoral region.] 



h. Lay the preparation on its left side and expose the sciatic nerve by 

 the same procedure as in the last exercise (PI. IX, figs. 1, 2) but not carrying 

 the exposure so far down the limb. Sever the hamstring division of the 

 sciatic near its origin above. Ligate as a single trunk the rest of the sciatic 

 (peroneal and tibial nerves together) low down and sever it distal to the 

 ligature. Dissect it up carefully for about 4 cm. 



c. Place the preparation on its right side and similarly prepare, ligate 

 and sever the left sciatic after severing its hamstring nerve. 



d. Pass a packing-needle (with thread-hole near its point, exerc. IV, 

 PI. I, fig. 2) armed with strong string through the skin and superficial part of 

 the calf-muscles of the left leg, about half-way between knee and ankle ; 

 withdrawing the needle, tie the string as tightly as possible round the leg, so 

 as to include the whole circumference of the limb. Amputate the leg about 

 2 cm. distal to this ligature, cutting the bones with the strong bone-pliers. 

 Transfix the pretibial skin and muscles near the end of the amputation-stump 

 with a strong needle, leaving the ends of the needle projecting. 



Drill a drill-pin into and through the condyles of the left femur, 

 inserting from the median side (PI. IX, fig. 8) and leaving the drill-pin in the 

 bone, as exerc. XVIII. Attach the drill-pin to the brass screw-holder and 

 clamp the latter to a vertical standard. 



e. Keeping the fore-quarters and head-stump of the preparation turned 

 on right side, so arrange the standard and clamped drill-rod that the left thigh 



