416 



BRANCHES OF THE LUMBAR PLEXUS. 





borum muscle to the crest of the ilium. It 

 then pierces the transversalis muscle, winds 

 along the crest of the ilium between the trans- 

 versalis and internal oblique, and divides into 

 two branches, abdominal and scrotal. The 

 abdominal branch, is continued forwards par- 

 allel with the last intercostal muscle to the 

 rectus muscle, to which it is distributed, send- 

 ing a branch forwards to the integument of 

 the abdomen. The scrotal branch opposite 

 the anterior superior spinous process of the 

 ilium, communicates with the inferior mus- 

 culo-cutaneous nerve, and escapes at the ex- 

 ternal abdominal ring, -with the spermatic 

 cord in the male, and with the round liga- 

 ment in the female. It is distributed to the 

 integument of the front of the os pubis and of 

 the groin, to the scrotum in the male and to 

 the greater labium in the female. The infe- 

 rior musculo-eutaneous nerve also^ arises^ from 

 the first lumbar nerve. 'Jt v is much smaller 

 than the preceding, crosses the quadratus 

 lumborum below it, and takes the same course 

 along the crest of the ilium. It terminates, 

 either by communicating, with the superior 

 nerve, or by. escaping with itUhrqug% the. Ex- 

 ternal abdominal ring and following the same 

 distribution. 



The External cutaneous nerve (inguino-cu- 

 taneous) proceeds from the second lumbar 

 nerve. It pierces the posterior fibres of the 

 psoas muscle; and crossing the iliacus ob- 

 liquely, lying beneath the iliac fascia to the 

 anterior superior spinous process of the ilium, 

 passes into the thigh beneath Poupart's liga- 

 ment. It then pierces the fascia lata at about 

 two inches below the anterior superior spine 



* A diagram showing the lumbar and sacral plexuses, with the nerves of the lower 

 extremity. 1. The five lumbar nerves ; which, with a branch from the last dorsal, 

 constitute the lumbar plexus. 2. The four upper sacral nerves ; which, with the last 

 lumbar, form the sacral plexus. 3. The two musculo-cutaneous nerves, branches of the 

 first lumbar nerve. 4. The external-cutaneous nerve. 5. The genilo-crural nerve. 6. 

 The crural or femoral nerve. 7. Its muscular branches. 8. Its cutaneous branches, 

 middle cutaneous. 9. Its descending or saphenous branches. 10. The short saphenous 

 nerve. 11. The long or internal saphenous. 12. The obturator nerve. 13. The gluteal 

 nerve ; a branch of the lumbo-sacral nerve. 14. The internal pudic nerve. 15. The 

 lesser ischiatic nerve. 16. The greater ischiatic nerve. 1 7. The popliteal nerve. 18. 

 The peroneal nerve. 19. The muscular branches of the popliteal. 20. The posterior 

 tibial nerve ; dividing at 21, into the two plantar nerves. 22. The external saphenous 

 nerve, formed by the union of the communicans poplitei and communicans peronei. 

 23. The anterior tibial nerve. 24. The musculo-cutaneous nerve, piercing the deep 

 fascia, and dividing into two cutaneous branches, for the supply of the dorsum of the 

 foot. 



