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AVES. 



which is analogous to the ulnar nerve, and the 

 other soon divides again into nerves which are 

 similar to the median and musculo-cutaneous. 

 The median dips down amongst the muscles on 

 the middle of the fore-arm, to which it gives 

 branches, and afterwards runs along the inter- 

 osseous space, passes under the annular ligament 

 of the carpus, and is distributed to the short 

 muscles of the digiti. The branch analogous to 

 the musculo-cutaneous nerve, is expanded upon 

 the muscles on the upper edge of the radius. 



11 The ulnar nerve, although it appears to be 

 incorporated with the median on the upper arm, 

 can be easily separated from it, and traced to its 

 proper origin in the brachial plexus. After this 

 nerve leaves the median, it turns over the end 

 of the foramen to get upon the edge of the 

 ulna. It gives filaments to the muscles in this 

 situation; but its chief branch runs down 

 superficially upon the ligaments of the quills in 

 company with a vein, and goes ultimately to 

 be lost upon the ulnar edge of the hand. 



" The third cord furnished by the brachial 

 plexus, supplies the place of the radial nerve. 

 It detaches several filaments to the muscles on 

 the inside and back of the scapula. It gives 

 off also the articular nerve, and then winds 

 round the humerus between the extensor mus- 

 cles, to which it furnishes some large filaments. 

 On coming to the outside of the humerus, it 

 sends a branch between the integuments of the 

 fold of the wing. The nerve now turns round 

 the neck of the radius, beneath the muscles, 

 and forms two branches ; of which one passes 

 under the muscles to the outer side of the ulna, 

 along which it runs superficially to the hand ; 

 the other branch passes on the radial side, but 

 more deeply amongst the muscles, goes under 

 the annular ligament of the carpus, proceeds 

 between the branches of the metacarpus, and is 

 finally lost on the back of the digiti." The same 

 anatomist describes the course of the nerves of the 

 posterior extremities as follows. 



" Although Cuvier has given a more accurate 

 description of the nerves of the lower extremity 

 than those of the wing, it nevertheless needs 

 correction in several particulars. 



" The obturator and femoral nerves arise 

 from the same plexus which is formed by the 

 two last lumbar nerves, by a communicating 

 branch from the first sacral pair. The obtu- 

 rator nerve passes through the upper part of the 

 foramen ovale, and is distributed to the muscles 

 around the hip-joint, especially the adductor. 

 The femoral nerve passes out of the pelvis in 

 company with the artery, over the upper edge 

 of the ilium. It divides into three branches, 

 which are dispersed among the muscles and 

 integuments on the anterior and inner part of 

 the thigh. Some of these filaments are long, 

 and descend superficially for a considerable 

 way upon the limb. 



" The ischiatic nerve is composed of the five 

 superior sacral nerves ; and as soon as it de- 

 parts from the plexus, even within the pelvis, 

 is easily separable into its primary branches. 

 Immediately after it passes through the ischi- 

 adic foramen, it sends filaments to the muscles 

 on the outer part of the thigh ; it then proceeds 



under the biceps muscle, along the back of the 

 thigh, about the middle of which it becomes 

 divided into the tibiul and the peroneal nerves. 



" The tibial nerve, even before it arrives in 

 the ham, separates into several branches, which 

 pass on each side of the bloodvessels, and are 

 chiefly distributed to the muscles on the back 

 of the leg. Two of these branches, however, 

 are differently disposed of; the one accom- 

 panies the posterior tibial artery down the leg, 

 passes over the internal part of the pulley, and 

 is lost in small filaments and anastomoses, with 

 a branch of the peroneal nerve on the inner side 

 of the metatarsus ; the other branch runs down 

 on the peroneal side of the leg, along the deep- 

 seated flexors of the toes, passes in a sheath 

 formed for it on the outer edge of the moveable 

 pulley of the heel, and proceeds under the 

 flexor tendons along the metatarsal bone, to be 

 distributed to the internal part of the two ex- 

 ternal toes. 



" The peroneal nerve is directed to the outer 

 part of the leg ; it dips above the gastrocnemii 

 muscles, and runs through the same liga- 

 mentous pulley that transmits the tendon of the 

 biceps muscle; it then detaches some large 

 filaments to the muscles on the anterior part 

 of the leg, under which it divides into two 

 branches, which proceed close together, in com- 

 pany with the anterior tibial artery to the fore 

 part of the ankle-joint, at which place they 

 separate ; one passes superficially over the 

 outer part of the joint, the other goes first 

 under the transverse ligament which binds 

 down the tendon of the tibialis anticus muscle 

 on the tibia, and then over the inner part of the 

 joint, below which it divides into two branches, 

 the one is distributed to the inner side of the 

 metatarsus and the tibial side of the pollex, 

 and to the next toe ; the other turns towards 

 the centre of the metatarsal bone, and pene- 

 trates the tendon of the tibialis anticus just 

 at its insertion, and then rejoins the branch 

 of the peroneal nerve it accompanied down the 

 leg. They continue'their course together again 

 in the anterior furrow of the metatarsal bone ; 

 and at the root of the toes, separate once more, 

 and proceed to the interspaces of the three 

 anterior toes, and each divides into two fila- 

 ments, which run along the sides of the toes to 

 the nail." Rees' Cyclopedia, Art. Birds. 



The great sympathetic nerve of birds resem- 

 bles, in many particulars, that of mammals. 

 It enters the cranium by the same orifice as 

 that by which the nervus vagus and the glosso- 

 pharyngeal make their exit; it there unites 

 with the fifth and sixth pair of nerves. At the 

 base of the cranium the first ganglion, or su- 

 perior cervical, is of a lenticular form, and 

 communicates at once with the ninth and eighth 

 pairs of nerves, so as to seem as if it were 

 blended with them. The remainder of the 

 chain of cervical ganglions are very remarkably 

 situated, being lodged on either side in the 

 canal of the vertebral artery formed by the trans- 

 verse processes ; into which it passes, or from 

 which it escapes above, at the third cervical 

 vertebra, while below the sympathetic again 

 becomes conspicuous at the commencement of 



