MAMMALIA. 



157 



those in man consists in a smaller size, a more direct course, and a less distribution on 

 the abdominal muscles, and by those at the lower part of the chest being covered by 

 an extension of the origin of the psoas muscle ; and in the anterior cutaneous branches 

 supplying the different portions of the mamma in the female dog as well as the skin : 

 the posterior trunks, after supplying the muscles connected with the spine, and the 

 sacro-lumbar and longest muscles of the back, send a branch between fibres of these 

 and the broadest muscle of the back to the skin. The anterior trunks of the lumbar 

 id sacral nerves supply principally the parts connected with the lower extremity, the 

 Bladder and rectum ; the two superior of the posterior trunks of the lumbar supply the 

 skin as well as the sacro-lumbar and other muscles connected with the posterior part of 

 ae lumbar vertebrae ; the lower five the muscles only ; the posterior sacral supply the 

 luscles connected with the posterior part of the tail. The nerves are not very 

 different from those in man except in their number, and consequently in their conjunc- 

 tion a little higher or lower for forming the nerves of the lower extremity. The 

 anterior trunks of the three first lumbar nerves give filaments to the psoas muscle, and 

 then pass forward to terminate in the abdominal muscles and skin. The fourth gives 

 filaments to the psoas and internal iliac muscles, and sends a branch to join one from 

 the third to form the external spermatic on the external iliac artery, which passes 

 through the external ring to the spermatic cord ; in a female dog this was distributed 

 on the last division of the mamma ; it sends off another branch which gives a filament 

 to the external iliac artery and then joins the fifth, the rest of the fourth passes down 

 on the exterior of the thigh to the skin, and forms the external cutaneous nerve. The 

 fifth receives a branch from the fourth, gives filaments to the internal iliac muscle, part 

 of it is then joined by a large branch from the sixth to form the anterior crural nerve ; 

 the other part after receiving a large and small branch from the sixth becomes the 

 obturator nerve. The sixth having given off the preceding branches joins the seventh 

 and the first sacral, and a branch of the second for forming the sciatic nerve. The 

 junction of the seventh lumbar and first sacral, gives a branch to the pyriform muscle, 

 and a larger one to pass out at the ischiatic notch to supply the gluteal muscles and 

 the tensor of the fascia of the thigh. Some branches derived from the first and second 



