ABDOMINAL SPINAL NERVES. 503 



its sheath and are ramified upon the integuments of the front of 

 the abdomen. 



The Twelfth Subcostal Branch of the Dorsal Nerves, sends 

 first a branch downwards, which joins with the first lumbar 

 nerve. It then crosses in front of the quadratus lumborum 

 muscle, to which it gives filaments as well as to the adjoining 

 portion of the diaphragm. It afterwards divides into two 

 branches, the superior of which goes for some distance between 

 the two oblique muscles of the abdomen, detaching filaments 

 to them, and finally terminates on the integuments of the ab- 

 domen : the other branch goes between the transversalis and 

 the internal oblique, and is extended to the lower part of the 

 rectus, and to the pyramidalis muscle, to all of which it distri- 

 butes filaments. 



SECT. III. OF THE ABDOMINAL SPINAL NERVES. 



There are five lumbar, and five sometimes six sacral nerves 

 on each side; the first of them passes out of the intervertebral 

 foramen, between the first and the second lumbar vertebra; and 

 the remaining lumbar and sacral nerves go, successively, 

 through the foramina in the loins and in the sacrum. 



The anterior fasciculi of these nerves form a plexus which 

 extends from the upper part of the loins to the lower part of 

 the sacrum; it is designated under the general term of Plexus 

 Cruralis. The posterior fasciculi are much smaller. Those of 

 the loins go backwards between the transverse processes, and 

 are distributed upon the sacro-lumbalis, the longissimus dorsi, 

 the multifidus spinse, and the corresponding integuments. The 

 posterior fasciculi of the sacral nerves are not so large, gene- 

 rally, as those of the lumbar: they get out through the foramina, 

 on the posterior face of the sacrum, are distributed to the same 

 muscles; to the origin of the glutaeus magnus, and to the inte- 

 guments of the sacrum, and of the adjoining portion of the but- 

 tocks. 



The Plexus Cruralis, for the purpose of description, has been 

 divided by anatomists into the Plexus Lumbalis, formed by the 

 four superior lumbar nerves, and the Plexus Ischiadicus, formed 

 by the last lumbar and the sacral nerves. 



