B I R 



The /^ mora! arfery is a fmall trunk which takes its origin 

 from the fide; of the aorta, oppofite to the notch in the bones 

 of the pelvis immediately under the lail rib. This notch is 

 formed into a round liole in the recent fibjefi, by a h'ga- 

 mcnt which is extended from it to the rib; ar.d it is through 

 this hole that the femoral artery makes its exit from the 

 pelvis; jull before it pafles out upon the thish, it fends off 

 a long branch which runs backwards the whole length of 

 the margin of the pelvis difpenfrng arteries to the abdo- 

 minal mufcles on one lide, and the obturator internus on 

 the other. This branch alfo appears to fupply one to 

 the oviduiS. The femora! artery, immediately after leav- 

 ing the pelvis, feparates into two branches ; one goes up- 

 wards and outwards, ramifying amongft the mufcles in 

 that fituation ; the other turns downwards, andisdidributed 

 to the flexors of the hmb, and round the joint, and lenda an 

 arteiy to the edge of tiie vailus internus, which can be 

 traced as far as the knee. The kidnics appear to derive 

 fome irregular inconfiderablc branches from the femoral ar- 

 tery while it is witliin the pelvis. 



The ifchiadk artery is the principal tnink of the lower ex- 

 tremity, exceeding very much in iize the femoral. When 

 it is produced by the aoita, it appears to be the conti- 

 nuation of that trunk ; the remni:;ing part of the aorta be- 

 comes fo much and fo fuddcnly diminifhed, and fcems as it 

 were to proceed as a branch from the back part of the vcflTel. 



The ifchiadic artery, while in the pelvi?, is concealed by 

 the kidnics, in which lituation it gives a branch from its 

 lower rule, wh.ich dindes into three others that are diflri- 

 buted to the fubllance of the kidnies ; one of thcfe on the 

 left fide is continued out of the kidney to be lofl; upon the 

 oviduft. The artery leaves the pelvis by the ifchiadic fora- 

 men, in company with the great nerve ; while within the 

 foramen, it gives a branch obliquely downwards under the 

 biceps to the mufcles lying on the pelvis ; and as it pafles 

 over the addudlor, it fends off another along the lower edge 

 of that mufcle, which is chiefly loll in the femimembranofus. 

 It then detaches feveral fmall brandies to the mufcles on 

 the outer and fore part of the thigh, fom.e of which anafto- 

 mofe round the j;)iat with the branches of the femoral arte- 

 ry. Jull as the ifchiadic arrives in the ham, it furnilhes a 

 Tery large branch downwards, which divides into two ; one 

 goes under the gaftrocnemiuj, to which and the deep feated 

 flexors its branches are dillributed as far as the heel ; the 

 other is analogous to the peroneal artery ; it goes to the out- 

 fide of the leg, fupplits the peroneal mufcles pofteriorly, 

 and pafTes along the outer edg»^ of the flexors of the toes to 

 the heel, above which, and behind the flexor tendon, it di- 

 vides, running on each lide of the heel, and forming feve- 

 ral articular arteries around the joint, and communicating 

 •with the other branch, and with the anterior tibial, and the 

 metatarfal branch of the plantar artery. 



The articular arteries go off next from the artery in the 

 'ham ; the two principal ones are deep feated. One pro- 

 ceeds under the vailus internus to the external part of the 

 joint ; the other is large, and fituated upon the infide. It 

 ■forms two veflels, one is the true articular artery, and 

 fpreads upon the ligaments of the joint, the other is diftri- 

 buted in the fubftance of the flexor of the heel, which is 

 placed upon the infide and fore part of the leg, and comes 

 out upon the edge of this mufcle to be loil in the inte- 

 guments. 



The pojlcrior tibial artery is extremely fmall; it only fup- 

 plies mufcular branches to the internal head of the gaftroc.^e- 

 mius, and fome of the flexors of tiie toes ; it is loll on the 

 infide of the heel in analloinofes with the peroneal artery, 

 and other fmall fuperficial branches. 3 



B I R 



The tnink of the artery of the leg now gets upon the- 

 pofterior furf;ice of the tibia, and fends off through the defi- 

 ciency left between the tibia and fibula at the fupsrrior part, 

 a branch, which is dillributed to all the mufcles upon the 

 fore part of the leg. The artery then creeps along the back 

 of the bones for fome way, and paffmg between them above, 

 wiiere the fibula is anchylofed with the tibia, it re-appears on 

 the anterior part of the kg in the fituation of the anterior ti- 

 liiil artery ; at this- place it detaches fome very fmall branches, 

 which frequently divide and unite again, to produce a motl 

 Angular reticiilation or plexus of veflels, which clofely ad- 

 heres to the trunk of the artery, and is continued with it as 

 far as the articulation of the tibia with the metatarfal bone, 

 where it difappears without feeming to anfwer any ufefu! de- 

 fign. Tliis plexus refembles in appearance exaAly the divi- 

 fion of the arteries of the extremities, which has been de- 

 fcribed by Mr. Carlile in the tardigrade quadrupeds, but 

 differs from it in this circumilance, that the trunk of the 

 artery is prefer\^ed behind it, without fuffcring any material 

 diminution of its fize. 



The anterior tibial artery furnifhes no branch of any im- 

 portance during the time it is proceeding along the fore part 

 of the leg. It palfes under the ftrong ligament which binds 

 down the tendons of the anterior mufcles of the leg, and 

 over the fore part of the joint on the infide ot the tendon of 

 the tibialis amicus ; at which place it dillributes fome 

 branches which inofculate with the other arteries round the 

 joint ; it then purfues its courfe in the groove along the an- 

 terior furface of the metatarfal bone, and covered by the 

 tendon of the fl^-xor digitorum. On coming near the foot, 

 it fends off an artery, which divides, behind the joint of the 

 internal toe, into two branches ; one goes between the in- 

 ternal and middle toes, ramifies upon both their joints, and 

 unites with the artery in the fole of the foot ; the other is 

 dillributed between tlie internal toe and the poUex or toe 

 which occupies the place of the great toe ; the main artery 

 now pafles to the fole of the foot through a hole in the 

 metatarfal bone left for the purpofe, when the original parts 

 of this bone were united by ofllfication. In this fituation 

 the artery might receive the name of the plantar. It has 

 fcarcely paffed through the bone, when it divides into fix 

 branches ; three of thefe are diftributed to the tendons and 

 ligaments, &c. on the outfide of the foot and the back of 

 the mctataiTus, anaftomoling with the defcending branches 

 of the peroneal artery ; tb.e fourth branch fupplies the pol- 

 lex, and alfo fends a branch upon the metatarfus. The re- 

 maining branches are defigned fur the three principal toes ; 

 one dips in between the internal and middle toe, unites with 

 the anterior branch of the metatarfal artery, and is diftri- 

 buted to the fides of thefe toes as far as their extremity. 

 The other divides, between the external and middle toe, into 

 two branches, which run upon the oppofite fide of each of 

 thcfe toes to the end. 



When the feet are webbed, the digital arteries fend off 

 numerous branches, which, ramifying in the membrane be- 

 tween the toes, eilablifh a communication with each other. 

 The prefent defcription has been taken from birds which pof- 

 fefs three principal toes, and the back toe, or poUex ; but no 

 material difference can be expeded in thofc with a greater 

 number of toes. 



After the trunk of the aorta has detached the ifchiadic 

 arteries, it is continued along ttie Ipine, fending fmall 

 branches analogous to the lumbar arteries, one of which 

 afcends upon the reftum, fupplies the place of the inferior 

 mejhileric, and unites with the fupcrior mefi.;-.teric, as 

 already mentioned. The aoita feparates above the coxy- 

 geal vertebre into three branches; two of thefe proceed 



late- 



