THE NERVOUS SYSTEM IN BIRDS. 791 



Common motores oculorum. Pathetici. External motores oculorum. There is nothing 

 particular to be cited respecting these. 



Trigeminal nerve. This nerve divides into three principal branches, as in the 

 domesticated animals. The ophthalmic branch has a nasal ramuscule that becomes 

 superficial, and extends to the extremity of the beak ; as well as a third filament that 

 is lost around the inferior orifice of the nasal cavities 



The superior maxillary issues from the cranium fey the opening through which the 

 lower maxillary nerve passes, creeps below the orbit, traverses the maxillary bone, and 

 terminates on the sides of the beak by filaments that resemble the infra-orbital 

 ramuscules of the Horse. 



The inferior maxillary furnishes two branches : one passes through the dental canal 

 and arrives at the extremity of the lower mandible ; the other is spread in the sub- 

 corneus 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 en- 

 tirely 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 \\ ith the vagus nerve to become superficial. 



Hypoglossal nerve. The same origin as in quadrupeds. Where it crosses the pneu- 

 mogastrio, 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 NERVES. 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 Gallinacese 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 col- 

 lateral ramuscules, and terminates by two fasciculi of branches. The first collateral 

 goes to the deep pectoral muscle : another is distributed to the muscles surrounding the 

 head of the humerus, as well as to the articular capsule. The fasciculi of terminal 

 branches may be distinguished, after their situation, as anterior and posterior. The 

 latter represents the internal cutaneous and radial nerve ; it gives off muscular and 

 cutaneous ramuscules 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 ex- 

 pended 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-sacral plexus. Two lumbar and four sacral nerves constitute this plexus. 

 In the Fowl it is distinctly divisible into two poitions, 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 fascia lata muscle ; 2, A crural or femoral nerve ,- 

 3, An internal saphenous nerve that descends to the leg ; 4, An obturator nerve. The 

 latter is very slender, and directed downwards and backwards, passing into the muscle 

 that closes the obturator foramen. 



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

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

 they unite ; during their course in the interior of the pelvis, they are surrounded by the 

 tissue of the kidney. The distribution of this portion of the plexus resembles that of 

 the Horse. Thus, in leaving the sciatic notch, it gives off the anterior and posterior 

 gluteal nerves, then two long branches that lie together as far as the gemelli ; these 

 branches are : 1, The great sciatic, with a ramuscule for the gemelli and the posterior 

 tibial muscles ; 2, The external popliteal, which, outside the superior extremity of the 

 leg, divides into the musculo-cutaneous and anterior tibial nevre 



