262 GENERAL ORNITHOLOGY part ii 



motor root simple. This nerve has three divisions, whence its 

 name ; 5rt, ophthalmic division, the most distinct ; exit from cranial 

 into orbital cavity by separate foramen above and to outer side of 

 optic foramen ; grooves orbital wall in passing ; ciliary ganglion ; 

 distribution mainly to lacrymal and nasal parts ; traceable to end of 

 upper mandible ; bh, superior maxillary ; exit by foramen ovale, in 

 alisphenoid or between that and prootic centre ; distribution to side 

 of upper jaw ; Meckelian ganglion ; Sc, inferior maxillary, derived 

 ■chieHy from motor root ; exit same as 5/^ ; distribution to lower 

 jaw (muscles, substance of bone, integument) ; no special sense (gus- 

 tatory) function ; no otic ganglion. 7, facial or portio dura, motor ; 

 origin from myelencephalon ; enters periotic bone, escapes from ear 

 behind quadrate bone, by what corresponds to stylomastoid fora- 

 men of mammals ; communicates with 5c by chorda tympani nerve, 

 with 9, 10, 12, and sympathetic system; distribution to skin- 

 muscles and others of lower jaw and tongue, etc. 8, auditory or 

 jjortio mollis, nerve of special sense (hearing) ; origin Avith 7 ; no 

 exit from skull ; enters meatus auditorius internus of periotic bone ; 

 forms auditory apparatus in labyrinth of ear. 9, glossopharyngecd, 

 mixed nerve, sensorimotor and gustatory (taste) ; origin myelence- 

 phalon ; exit by foramen in exoccipital bone, behind basitemporal, 

 near lower border of tympanic recess ; distribution to muscles and 

 membranes of gullet, throat, tongue, etc. \0, pneiimogastric, sensori- 

 motor ; origin and exit next to 9 ; distribution to windpipe, lungs, 

 gullet, stomach, heart, etc. ; has recurrent syringeal to vocal organs. 

 11, spincd accessm-y, sensorimotor; origin upper part of spinal cord ; 

 exit with 9, 1 ; distribution to these nerves and to muscles of 

 neck. 9, 10, 11, are intimately connected with one another, and 

 with other nerves, especially 10 with sympathetic. The several 

 foramina in a bird's skull, which may be seen in the place indicated 

 at 8, Figs. 69, 70, are for the divisions of this composite vagus or 

 " wandering " nerve of respiration, circulation, digestion, etc. ; they 

 represent morphologically a foramen lacerum posterius, between ex- 

 occipital and opisthotic centres. 1 2, hypoglossal, motor nerve of the 

 tongue ; origin from myelencephalon ; exit by anterior condyloid 

 foramen in front of the occipital condyle. Thus the plan of the 

 cranial nerves of birds is nearly coincident with that of mammals. 



The Spinal Nerves, in pairs, correspond in a general way to 

 the vertebree, between which they pass out by intervertebral fora- 

 mina, to supply the body at large. They are sensorimotor ; arise 

 from the spinal cord by anterior motor and posterior sensory 

 (ganglionated) roots which unite before leaving the spinal canal ; in 

 the sacral region the main branches leave by separate foramina. 

 They form plexuses or interlacements. The principal of these is the 

 brachial plexus ; constituted by several lower cervical nerves, and 



