THE NERVOUS SYSTEM IN BIRDS. 897 



The inferior maxillary furnishes two bi*anches : one passes through the dental 

 canal, and arrives at the extremity of the Lower mandible ; the other is spread in 

 the subcorneus integuments of the same. 



Facial nerve. — This is small in Birds. " It is distributed to the muscles 

 of the jaws and the small muscles which erect the feathers of the crest" 

 (Cuvier). 



Glosso-pharyngeal nerve. — This calls for no remark. 



Pneumogastric nerve. — There are few differences observed in this ; it is as 

 extensive as in Mammals, and its anastomoses and relations are nearly the same. 

 It is not entirely formed at its exit from the cranium, and always offers two or 

 three constituent filaments that join it, and are confounded at some distance 

 from the point of emergence. The recurrents furnish ramuscules to the crop. 



Spinal accessory nerve. — This likewise has a medullary root that appears at 

 the third cervical vertebra ; it runs along with the vagus nerve to become 

 superficial. 



Hypoglossal nerve. — The same origin as in Quadrupeds. Where it crosses the 

 pneumogastric, it detaches a long filament that passes along with the jugular 

 vein towards the chest. On the sides of the larynx it bifurcates ; one branch 

 proceeds forward beneath the tongue, the other follows in the same direction, but 

 on the upper surface of that organ. 



Spinal Nekves. — We need only notice the nerves of the wing and pelvic 

 limb, the others being disposed in a similar manner to those above described. 



Brachial plexus. — Three principal branches — the last cervical and first two 

 dorsal — form this plexus in Palmipeds ; in the Gallinaceae there are four — 

 the last three cervical and first dorsal. These branches anastomose beneath the 

 deep face of the scapulo-humeral articulation. When fully constituted, the 

 plexus gives off some collateral ramuscules, and terminates by two fasciculi of 

 branches. The first collateral goes to the deep pectoral muscle ; another is dis- 

 tributed to the muscles surrounding the head of the humerus, as well as to the 

 articular capsule. The fascicuh of terminal branches may be distinguished, 

 after their situation, as anterior and posterior. The latter represents the internal 

 brachial, cutaneous, and radial nerves ; it gives off muscular and cutaneous ramus- 

 cules that extend to the digits at the extremity of the wing. The anterior 

 fasciculus is larger, and is also extended to the whole of the limb, being expended 

 in motor and sensitive filaments ; near its origin it furnishes ramuscules to the 

 superficial pectoral muscle. This fasciculus represents the median, ulnar, and 

 anterior brachial, or musculo-cutaneous of Mammals. 



Lumbo-sacrcd plexus. — Two lumbar and four sacral nerves constitute this 

 plexus. In the Fowl it is distinctly divisible into two portions, an anterior and 

 posterior, considerably wide apart. 



The anterior portion is composed of the lumbar branches and a portion of the 

 first sacral ; their fusion takes place on the salient bony ridge that separates the 

 lumbar from the sacral regions. It gives origin to four or five branches, among 

 which are clearly discernible : 1. A. filament to the tensor fascia lata muscle. 2. 

 A crural or femoral nerve. 3. An internal saphenic nerve that descends to the 

 leg. 4. An obturator nerve. The latter is very slender, and directed down- 

 wards and backwards, passing into the muscle that closes the obturator 

 foramen. 



The posterior portion comprises a portion of the first sacral, and the whole of 

 the three succeeding nerves. These are directed outwards, towards the sciatic 



