410 



DR. 0. F. SONNTAG ON THE ANATOMY, 



on the extensor aspect of the forearm. Finally it sends a long, 

 fine nerve to the wrist joint. 



The internal cutaneous and lesser internal cutaneous nerves arise 

 from the conjoined median and ulnar nerves in the brachial 

 plexus. They are distributed as in Man. 



The intercosto-humeral nerve is as in Man. 



The Lumhar and Sacral Plexuses (text-fig. 49). 



The lumbar plexus is formed by the anterior primary divisions 

 of the four lumbar nerves, the sacral plexus is formed by the 



Text-figure 49. 



G.S.N 



The lumbo-sacral plexus. DXIII-S2: nerves forming the plexus proper; S3 and 

 S4, not shown in the diagram, supply pelvic muscles; Pyr : nerves to pyri- 

 formis ; H.M. and Q.F : nerves to the hamstring muscles and quadratus 

 femoris. Other letters in text. 



anterior primary divisions of the four sacral nerves, The two 

 plexuses are connected by the lumbo-sacral cord from the third 

 and fourth lumbar nerves. Hepburn (24) gives the cord as coming 

 from the fourth lumbar, Champneys (11) records a totally 

 different formation of the plexuses, but does not mention the 

 cord. Bolk (7) showed that thei-e are slight variations in 

 different animals. 



The following table shows the origins of the nerves as observed 

 by myself and others : — 



