NEUROLOGY. 135 
_ Pl. 188, fig. 4, brachial plexus unravelled: " ’, fifth and sixth cervical 
nerves; *, branch arising from the union of the two and dividing into ‘, the 
musculo-cutaneous nerve, and °, a connecting branch of the median nerve ; 
*7 eighth cervical and first dorsal nerve; °, their connexion, and °, their 
division into a branch going to the median nerve, the ulnar nerve ”, and 
the internal cutaneous nerve "; , small internal cutaneous nerve ; *, median 
nerve; ‘*™, radial nerve; “, posterior thoracic. /%g. 6, relations of the 
digital nerves or the palmar side: »’, digital nerves; *, plexus at the tip of 
the finger formed by the union of the two. yg. 7, relations of the digital 
nerves or the dorsal surface: ”’, dorsal nerves; *’, branch of the preceding 
nerves passing round to the dorsal surface. 
4. THe DorsaL NERVES are twelve in number on each side. The first 
pair passes between the two first dorsal vertebrze, the last pair between the. 
last dorsal and first lumbar vertebree ; the first is very large, the following 
diminish in size, but the two last again increase, and the twelfth is nearly 
equal to the first. These nerves are distributed to the parietes of the 
thorax and abdomen, also to the muscles and integuments on the posterior 
and lateral regions of the trunk; they are not connected together in any 
plexus like the cervical, lumbar, and sacral nerves, but are distributed 
separately. All their anterior branches, however, are united through the 
medium of the chain of the dorsal sympathetic ganglions, each of the former 
being connected by one or two filaments to one of the latter; the first 
dorsal also joins to the last cervical in the brachial- plexus, and the last 
dorsal is connected to the first lumbar; they all divide into a posterior and 
an anterior or intercostal branch. The posterior or dorsal branches are 
smaller than the anterior; they each pass backwards, accompanied by the 
posterior branch of the intercostal artery, through a foramen formed above 
and below by the spinous processes, internally by the bodies of two verte- 
bree, and externally by the anterior or great costo-transverse ligament ; 
they supply the muscles and integuments of the back and loins. 
The anterior dorsal nerves, excepting the first, are named the intercostals, 
and pass round the parietes of the thorax between the laminz of the inter- 
costal muscles, and inferior to the intercostal blood-vessels: the superior 
five or six are confined to the chest, and extend as far as the sternum; the 
anterior portions of the inferior five or six are placed in parallel lines 
between the abdominal muscles, and extend to the rectus. They supply 
the parietes, muscles, and integuments of the thorax and of the upper part 
of the abdomen. 
5. THE Lumbar Nerves. There are five pairs. They are larger than 
the dorsal, and increase in size downwards; the first escapes between the 
two first lumbar vertebree, the fifth between the last vertebrae and the 
sacrum; like the dorsal, they divide into posterior and anterior branches. 
The posterior pass between the transverse processes to the lumbo-spinal 
muscles, and each divides close to the multifidus spinz into an internal and 
external branch; the former is lost in the multifidus spine, inter-spinous, 
and inter-transverse muscles; the external branch is large and musculo- 
cutaneous, supplying the sacro-lumbalis and lumbar aponeurosis. The two 
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