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The rtmain Jlt of the vertebral artery is continued Upwards 

 in the canal formi-d in the tranfverfc proccflos of the cervical 

 vcrtcbi-x, diminifhing: gradually in confequence of branches 

 it fends off between each vertebra to the fpinal marrow and 

 the mnfcles of tlie neck. Near the head, the artery is found 

 confiderably reduced ; and within the lall foramen in the 

 tranfverfe proceffcs. terminates entjrely by inofcubtion with 

 the rcfleaed branch of the carotid, as before noticed. 



The extraordinary anaftomofc* and the plexules which are 

 to be obfcrved in the arteries of the head in birds are not 

 eafily accounted fi.r. It ftems pofTilde that they may be re- 

 quired in confequence of tlie great length of the neck in 

 thcfe animals ; il bcinpr well knowa that frcqnct-.t communi- 

 cation amjngft the \<:i^.h, ahhouj^h it dimiiiifiics the impe- 

 tus of the circ:J.ition, infures a free and uninterrupted mo- 

 tion of the blood. 



After the common trunk of the carotid and vertebral is 

 detached from the artcria innominata, this veffel may atTume 

 the name of th-- fuh/.tvian. ^V■hile paffnig under the cla- 

 viel-, it fends off iome important branches : the fnil: might be 

 called a /'f(73ni/ flc/f/-)', it proceeds upwards upov. the inter- 

 nal furface of the peftoralis minimus mufcle, which it lup- 

 phes ; and tlicn dividing into two branches, one pafles over 

 the anterior edge of the clavicle, and under the peftoralis 

 medius, between which and the fternum it runs, detaching 

 its branches to the mnfcle ; the other fends firll along the 

 under fide of the clavicle a branch which is again fnbdivided 

 and dillributed to the outfide of the Ihonlder joint and to 

 the deltoid mufclo, in which it inofculates with the articular 

 arterv. The vclfel then paffes between the clavicle and the 

 fork-fliaped bone, and on a ligament which connefts the 

 head of the clavicle to that of the fcapula, and difperfcs its 

 branches upon the upper part of the fhoulder joint forming 

 anaftomofes with the neighbouring arteries. 



The next branch of the fubclavian is the humeral artery ; 

 it arifes from the upper fide of the vtffel, and makes a (light 

 curve to reach its fituation on the infidc of the arm, in order 

 to difpenfe its branches in the manner hereafter defcribed. 



The internal mammary artery is given oif juft as the fub- 

 clavian leaves the chell. It divides into three branches, 

 one ramifies upon the inner furface of the llernum ; another 

 upon the fternal ribs, and the intercoflal mufcles ; and the 

 third runs along the anterior extremities of the vertebral 

 ribs, fupplying the intercollal mufcles, &c. 



The chief peculiarity of the arteries of the fuperior ex- 

 tremity in bird?, coniills in the great magnitude of the 

 velfcls which fupply the pecloral mufcles ; thcfe, inllead 

 of being ineoiifiderable branches of the axillary artery, are 

 the continuations of the trunk of the fubclavian, of which 

 the humeral is only a branch. 



The great petloral or thoracic artery palTts out of the 

 cliell over the firll rib, and clofe to tiie llernum, and iin- 

 inediacely divides into two branches. One of them ramifies 

 in the fuperior part of the p-ftoralis major, and the otlier is 

 exhau.led in the lo.ver part of the mufcle, and fends off a 

 branch analogous to the long thoracic artery of mammaha. 



The humeral artery, while within the axilla, gives a fmall 

 branch backwards to the mufcles, under the fc.ipula, and 

 upon reaching tlie infide of tlie arm produces an artery, that 

 foon divides into tlie articular and the profunda humeri. 

 The articular artery paffes round the head of the humerus, 

 underneath the extenfors ; its branches penetrate the deltoid 

 mufcle, and anallomofe with the other fmall arteries around 

 the joint. 



The profunda humeri as ufual turns under the extenfor 



. mufcles, to reach the back of tiie bone, at which place, in 



birds, it feparates into two branches, of whicli oue dcfcends 



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upon the infide, and the other upon the outfide of the artJ- 

 culation of the humerus with the radius and ulna, and there 

 inofculate with the recurrent branches of the arteries of tha 

 fore arm. 



After the humeral artery has fent off" the profunda, it de- 

 fcends along the inner edge of the biceps mufcle, detaching 

 fome branches to the neighbouring parts ; upon arriving at 

 the fold of the wing it divides into tvn branches, one of 

 thefe is analogous to'the ulnar artery, and the other from its 

 pofition deferves to be called rather the ir.teroffeous than the 

 radial artery. 



At the place where the humeral produces the two arteries 

 of the fore arm a fmall branch is fent oft", which is loft upon 

 the fore part of the joint, and in anaftomofes with the recur- 

 rent cf the ulnar, and the profunda hun-.eri. 



The ulnar artery is the principal divifion of the humeral ; , 

 it proceeds fuperficially over the mufcles which are ana- 

 lai'uus to the pro.iator, fends a large recurrent branch under 

 the flexor ulnaris to tlie back of the joint upon which it 

 ramifies and forms anaftomofes with the profunda humeri. 

 The artery then proceeds along the inner edge of the ulnar 

 mufcles, to which it diftributes branches. It is afterwards 

 fecn pafiing over the carpal bone of the ulnar fide, and under 

 the annular ligament, at which place it fends off fome 

 branches which fpread upon the joint and inofculate with 

 fimilar ones of the interolfcous artery. "Very foon after the 

 ulnar artery gets upon the metacarpus it dips in between 

 the bones and re-appears upon the oppofite fide lying under 

 the roots of the quills, to each of which it fends an artery ; 

 it preftrves this fituation to the end of the metacarpal bones, 

 where it paffes between the Ilyle analogous to the httle finger 

 and the principal or fore finger, and purfues its courfe 

 along the edge of the latter, to the extremity of the wing, 

 fupplying each of the true quills with an artei-y and fending 

 at each joint of the finger, a crofs branch to communicate 

 with the anaftomofing branches on the oppofite fide. 



The inlcrij/fesus artery detaches firft a branch of fome fizc 

 to the membrane which is fpread in the fold of the wing,, 

 upon which it forms fcveral ramifications. After this the 

 artery dips down behind the pronator ^ufcles to get into 

 the fpace between the ulna and radius. It here gives a 

 branch backwards to communicate with the others about the 

 joint, and proceeds in the interoffeous fpace as far as the 

 carpal joint, duiing which courfe tiiey become much dimi- 

 iiilhed ftom giving off feveral brandies which are diftributed 

 to the integuments and the quills placed upon the outfide 

 of tlie ulna. The remainder of the interoffeous artery is ex- 

 pended in fmall branches upon the back of the carpal jui:it, 

 the bartard quills, and along the radial edge of the meta- 

 carpus and bones of the fore finger, where it forms communi- 

 cations witii the crofs branches of the ulnar artery already 

 mentioned. 



From this defcription it will be perceived, that no artery 

 exifts in birds (tritlly analogous to the radiil ; that there are 

 no palmar arches ; and t:;at the fize of the interoffeous 

 artery, and the courfe of the ulnar along the outfide of the 

 n'etacarpus are peculiarities v.-hich arife from tho neccffity of 

 affording a large fupply of blood to the quills during their 

 growth. 



The (Icfccnding aorta makes a curve round the right auricle 

 in order to get upon the polterior furface of the heart, after 

 which its courfe is clofe along the fpine, in which fituation 

 it is bound down by cellular fubftance, and the ftrong mem- 

 brane or aponeurofis, which covers the lungs on their an- 

 terior part. The firll branches which this veffel appears to 

 fend off are bronchial arteries ; they arife from the fore part 

 of the aorta jult when it arrives upon the fpine j and having 



entered 



