634 



ABDOMINAL SPINAL NERVES. 



FIG. 204. 



and divide into external and internal branches. The for- 

 mer supply the longissimus dorsi, sacro-lumbalis, trape- 

 zius, rhomboid, latissimus dorsi, and adjacent integu- 

 ment. The internal supply the multifidus spinae, the long 

 muscles of the back, and can likewise be traced to the 

 integuments. 



The abdominal spinal, or lumbar nerves. These consist 



of five pairs, and are 

 larger than the dorsal. 

 They pass through the 

 intervertebral foramina, 

 the first pair between 

 the first and second 

 lumbar vertebras the 

 fifth between the last 

 vertebra and the sa- 

 crum. Like the dorsal, 

 these nerves consist of 

 anterior and posterior 

 branches. The anterior 

 are the largest, and pass 

 through and behind the 

 psoas magnus, uniting 

 with each other to con- 

 stitute the lumbar plexus. 

 The first lumbar unites 

 with the last dorsal. 



The lumbar plexus is concealed by the psoas magnus 

 muscle, and is situated upon the sides of the lumbar verte- 

 brae in front of their transverse processes. 



The branches of this plexus are divided into the super- 

 ficial and terminal. The superficial are again divided into 

 the abdomino-crural and genito-crural, and consist, accord- 



FIG. 204 represents the Lumbar and Ischiatic Plexuses, a Lumbar plexus. 

 . 6 Ischiatic plexus, c c Abdominal crural nerves, d External cutaneous 

 nerve, e f g Cutaneous branches from h Anterior crural nerve, i Genito- 

 crural. j j Termination of the sympathetic, k Iliacus internus muscle. I 

 Broad muscles of the abdomen, m Psoas magnus. n Bodies of lumbar verte- 

 bra, o Quadratus lumborum. p Diaphragm, q Sartorius muscle. 



