822 



NERVOUS SYSTEM OF THE HORSE 



THE LUMBAR NERVES 



There are six pairs of lumbar nerves (Nn. lumbales) in the horse, the last of 

 which emerge between the last lumlDar vertebra and the sacrum. The anterior two 

 or three are about the same size as the thoracic nerves, but the others are much 

 larger. 



Their dorsal branches are small in comparison with the ventral ones. They 

 are distributed to the muscles and skin of the loins and croup in a fashion similar 

 to those of the thoracic nerves. 



The ventral branches are connected with the sympathetic by small rami 

 communicantes, and give branches to the sublumbar muscles. Those of the first 

 two nerves are arranged in a manner analogous to the corresponding branch of the 

 last thoracic nerve. 



The ventral branch of the first lumbar nerve is termed the ilio-hypogastric 

 nerve (N. iliohypogastricus). It passes outward between the quadratus lum- 



Crura of 



Diaph 



Last thorn 



lie 



Ilio-hypogastric 

 nerve - 

 Ilio-inguinat nerve 

 External spermatic 

 nerve 

 External culaneo 



nerve 



Splanchnic nerve 

 Last intercostal arteries 

 First lumbar arteries 



Attachments of psoas major 

 Z,,k~~ Body of vertebra 



'-—External spermatic nerve 



Trunk of lumbar arteries 



Sixth lumbar artery 



Sympathetic 

 trunks 



Insertion of quad- 

 ratus lumboruni~^'~---?^ 



Anterior part of f 

 lumbosacral plexus [ZII^- 

 Obturator nerve 

 Femoral nerve 



Fig. 656.- — Lumbar Nerve9 of Horse; Ventral View. (After Schmaltz, Atlas d. Anat. d. Pferdeg.) 



Ventral sacro-iliac 

 ligament 



borum and the psoas major, and divides at the lateral border of the latter into a 

 superficial and deep branch. The superficial or cutaneous branch passes over the 

 dorsal edge of the internal oblique, descends between that muscle and the external 

 oblique, perforates the latter, and runs do^vnward and backward and ramifies 

 under the skin of the posterior part of the flank and the lateral surface of the thigh. 

 It gives branches to the transversus and obliquus externus abdominis. The deep 

 (or muscular) branch is smaller; it runs downward and backward beneath the 

 peritoneum to the lateral border of the rectus abdominis, gives branches to the 

 internal oblique, and terminates in the rectus abdominis. 



The ventral branch of the second lumbar nerve is usually connected by an 

 anastomotic branch with that of the third nerve. It gives off a large branch to the 

 psoas major and is continued as the ilio-inguinal nerve (N. ilioinguinalis). This 

 divides like the Uio-hypogastric into superficial and deep branches. Its superfi- 

 cial branch perforates the external oblique muscle a little in front of the point of 

 the hip, runs downward on the front of the thigh and the lateral surface of the 

 stifle, and gives off cutaneous branches. The deep branch runs behind and parallel 

 with that of the ilio-hypogastricus and detaches branches to the abdominal muscles. 



