AOR
A P A
Imperforate Akus. — Children are fomctimes born without an Anus ; and it is very difficult to hie on the right part for milk- ing a perforation into the rectum of children thus born ; be- caufe the extremity of the gut is generally formed into a knot. For performing fuch a perforation Mr. Petit recommends a trocar, the canula and circular plate of which are fa flit open, as to ferve as a groove for a biftoury to be run in, to en- large the aperture after the trocar has been pufhed into the gut. See Mem. de L'Acad. de Chirurg. Tom. i. Anus of the Brain is properly the pcfterior orifice of the ca- nal called aquezduStus fylvii. Hcijl. Comp. Anat. n. 270. See Aqujeduct.
The appellation Anus was probably occafioned by this, that the prominent medullary parts between which this canal paffes, are on account of their figure called nates, and tejles j whence it was natural enough to give tins aperture between them the title of Anus, as that of vulva was given to the oppjfite, or anterior orifice. Burggr. Lex. Med. in voc. AORIST {Cycl.) — Critics are divided as to the proper and primary import of the Greek Aorijis. Some take them for mere variations of the prreterperfeft tenfe, introduced only for copia fake without any peculiar fignification ; but it is certain the antient grammarians of that nation allowed a dif- ference between the Aorijis and praetcr tenfes. According to them, the prreterpcrfect tenfe expreffes a thing juft now or lately compleated ; whereas the Aorijl denotes it paft, but indeterminately without regarding whether it were lately or long ago. This diftinftion however is rejected by Gretfer, who produces inflanccs among the antients, where the two are ufed indifferently. Urfinus* alfo allows this promifcuous ufe, ; but looks deeper into the origin and reafn of the Aorijl. According to this writer, an Aorijl is then properly ufed
- ofirwr, as an Aorijl, when it does not denote any certain
or definite time, but in reality comprehends all times. That this is the primitive ufage of the Aorijl, he fhews by a great number of inflanccs. This appears a peculiarity in the Greek tongue, unknown in any other language, to have a tenfe merely indefinite, yet comprehending all the other tenfes h — [ a in Epift. ad Aveman. ap. Ejufd. Onomaft. German- Graec. in fine. b Aft. Erud. Lipf. 1690. p. 47 t.] The Greeks ufually diilinguifh two Aorijis. Some however will not allow of any fecond Aorijl, maintaining that what grammarians call the fecond Aorijl is the fame tenfe with the firft, only under a little difference of termination. Bibl. Anc. Mod. T. 5. p. 250. AORISTIA, Aofirta, in the fceptic philofophy, denotes that ftate of the mind wherein we neither afiert nor deny any thing pofitively, but only fpeak of things as fecming or appearing to us in fuch a manner. Sext. Empir. Pyrrhon. Hypot. I. 1. c. 26. Stanl Hilt. Philof. P. 12. c. 26. p. 788. The Aorijlia is one of the great points or terms of fcepti- cifm, to which the philofophcrs of that denomination had continual recourfe by way of explication, or fubterfuge. Their adverfaries the Dogmatics charged them with dogmatizing, and afferting the principles and pofitions of their feft to be true and certain. AORTA {Cycl. )— Anatomifls treat of the ftrufture of the Aorta, compreffion of the Aorta, valves, coats, ramifications, £sSV. of the Aorta. Vieuflens^ alfo fpeaks of a kind of vehicular glands in the parietcs of the Aorta. Dr. Keil b gives a com- putation of the velocity of the blood in the Aorta, — [* Aft. Emd. Lipf. 1705. p. 459. ^Fouv. Rep. Lett. T. 35. p. 214. b EfT. on Anim, CEcon. p. 138.]
The Aorta (filling from the heart by one only trunk, is furnifhed with three femi-lunar valves to prevent the blood's regurgitat- ing : immediately above tliefe it fends out to the heart two ar- teries called Coronaria ; and afterwards bending down in form of a bow, divides itfelf into what they call its afcending and de- fending parts. Heijl. Comp. Anat. n. 293. Keil, Anat, c. 7. Seft. 5. Drake, in Anthrop. 1. 3. c. 15. gives a fine figure of the Aorta. See alfo Phil. Tranf. N°. 280. p. 11 88- Afcending Aorta, or rather trunks of the Aorta, are thofe which take their courfe towards the upper and lateral parts of the body. Such are the two carotids, the fubclavian, cer- vical, fcapular, upper intercoftal, mediaftinal, upper diaphrag- matic, mammary, axillary, and brachial arteries. Defending Aorta, or trunk of the Aorta, fometimes alfo called fimply Aorta, is that which takes its courfe downwards thro' the thorax and abdomen to the os Jacrum, From this arife Ruyfch's bronchial artery, the lower inter corrals, sfo- phageous, lower diaphragmatic, cseliac, epiploic, emulgent, fpermatic, mefenteric, and hypogaffric arteries. The divifion of the Aorta into afcending and defcending trunks, tho* generally received by anatomifls is excepted to by Heiiter as lefs natural ; and fuited rather to the flrufture of quadrupeds, as dogs, calves, and the like, from which it feems to have been originally taken, than to that of the human body. In reality the afcending Aorta is not one fingle trunk as the name fliould import, but confifls of three large branches or trunks in fome inftances there have even been four obferved, fcarce . ever only two, and never one j which however is ufually the cafe in quadrupeds.
The flexure of the Aorta after its quitting the heart, and before its divifion into afcending branches, is noted by Dr. Lower as
an inftance of the wifdom of the creator ; to effeft a more equable and gentle diitribution of the blood to the feveral parts of the body. For whereas the orifice of the heart opens right upwards, if the Aorta, which receives the firft impulfe, were continued in a ftraight line up to the region of the head, the blood would be poured too fwiftly and plentifully on the brain, and the inferior parts be defrauded of their vital li- quor. To obviate this the Aorta is fo difpofed that the blood does not run directly into the afcending branches, the axillaries and carotids, but fetches as it were a compafs by means of the flexure, which fuftains the firft effort of the ejefted blood, and directs the greateft torrent towards the defcending trunk. Ray, Wifd: of God in Great. P. 2. 356.
The Difpofition of the Aorta is varied according to the kinds of animals, their different poftures, and other occafions : in man, by reafon of his erect fituation, the blood tends to flow fafter and more plentifully by the defcending than by the af- cending trunks j in brutes, which bend downwards, the con- trary ; in both, proper provifions are made for an equable dii- tribution. In the male fex of our fpecies, Dr. Pitcairn allures us, the defcending Aorta has fewer ramifications, and confe- 1 quently the blood will flow flower proportionably than in that of the female fex, where there are more ramifica- tions, and confequcntly the blood finding lefs refiftance will flow more largely to the lower parts of women than men, from which caufe arife the menfes. Jour, des Scav, T. 56.
P, 53°-
I he defcending Aorta is liable to compreflionj from the ftomach and intellinal tube, and that either ordinarily or extraordinarily. The firft happens whenever the ftomach, &c. is full j the fecond, when it is dilated beyond mea- fure by the plethora and ebullition excited in fevers. The effect in either cafe will be an interruption or diminution of the flux of blood to the lower parts of the body ; and an increafe of that to the head, and higher parts. The ordinary,' according to Dr. Woodward, is neceflary to fupply the bufi- nefs of cogitation, furnifh matter for animal fpirits,Vc*. The extraordinary ferves M. Silva b to account for the violent head- achs, deliriums, and other fymptoms of fevers. — [ a Jour, des Scav. T. 69. p. 592. b Id. T. 89. p. 457.3 The Aorta is found in divers flares, natural, morbid, oflificd, cartilaginous, aneuryfmatical, polypofe, calculofe, &c. Some will have oflifications of the Aorta one of the great caufes of fudden deaths. Hift. Acad. Scienc. 1701.P.35. feq. In an old man who died at the age of 130, Dr. Keil found the Aorta in the abdomen and fliacs to be for the greateft part cartilaginous, which apparently was one caufe of his death. Phil. Tranf. N". 306. p. 2248. feq.
The academifls naturae curioii give an inftance of fix nail-like ftones, or calculi, found in a prominence of the Aorta, under the kidneys of a perfon who had died of a mofl acute pain in the region of the loins. At each puliation of the artery, thefe would be driven againft the membranous fibrillae of the coat of the veflel, and hence thofe fhooting pains ; the caufe of concretion is attributed to the too frequent ufe of the vipe- rine powder, taken for an ulcerated breaft. V. Ephem. Acad. N. C. Cent. 9. App. Obf. 1. For the finus's of the Aorta, fee Sinus. APiEDEUSIA, A7t«i3Wi«, denotes ignorance or unfkilfulncfs in what relates to learning and the fciences. Hence alfo perfons uninftrufted and illiterate are called Apa- deutee.
The term Ap<zdeuice was particularly ufed among the French in the time of Huet ; when the men of wit at Paris were divided into two factions, one called by way of reproach Apts- deutee and the others Eruditi.
The Aptsdeuta: are reprefented by Huet, as perfons who finding themfelves cither incapable or unwilling to un- dergo a fevere courfe of ftudy, in order to become truly learned, confpired to decry learning and turn the knowledge of antiquity into ridicule, thus making a merit of their own incapacity. Vid. Mem. de Trev. An. 1722. p. 1310. feq. The Apadeutte in effect were the men of pleafure. The Eruditi the men of ftudy. The Ap<zdeut& in every thing preferred the modern writers to the antient, to fuperfede the neceflity of ftudying the latter. The Eruditi decried the moderns, and valued themfelves wholly on their acquaint- ance with the antients. APAGMA {Cycl.) is more properly ufed for a fracture of a bone, at or near the part whereby it is articulated with ano- ther. Cajl. Lex. Med. p. 59. APAGOGE, Avayuy,,, {Cycl.) in the Athenian law, the car- rying a criminal taken in the fact, to the magiftrate. If the accufer was not able to bring him to the magiftrate, it was ufual to take the magiftrate along with him to the houfe where the criminal lay concealed, or defended himfelf, Vid. Pott. Archaeol. Grsec. I. 1. c. 23. Apagoge, in mathematics, is fometimes ufed to denote a pro- grefs or paflage from one propofition to another ; when the firft having been once demonftrated, is afterwards employed in the proving of others. MUrcel. Lex. Phil. p. 143. APALACHINE, in botany, a name given by fome authors to the fhrub, called Caffine vera fioridanorum by other writers. Ind, Med. p. n.
APAN-
