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 277 Part VI. A N A T O M Y. In general, thefe arches are very confiderable in Thefe parts are the heart, pericardium', trunk of the young perfons; become gradually more fuperficial in aorta, a portion of theafpera arteria and of the oefophamarried women, and are quite loft in time of delivery. gus, the dudus ladeus or thoracicus, the lungs, ire. The inner or pofterior extremity of this great canal The hard parts, which form the fides of the cavity of furrounds the orifice of the uterus, a little obliquely, in the thorax, are the twelve vertebras of the back, all the inch a manner, as that the upper fide of the canal lies ribs, and the fternum. The foft parts, which complete Very near the orifice, and the lower fide at a greater the fides, are the membrane called pleura, which lines diftance from it, and this makes the extremity of the u- the cavity, and the mufculiinter-coftales, fterno-coftales, terus appear to advance mere into the canal on the lower and diaphragma. All thefe hard and foft parts taken together reprefent than on the upper part. The exterior or anterior extremity of the great canal a kind of cage, in fome meafure of a conical figure, flatin virgins, and efpecially before the firft eruption of the ted on the forefide, depreffed on the backfide, and in a 'jnenfes, is commonly bordered by a circular membranous manner divided into two nooks by the figure of the vertefold, of different breadths, more or lefs fmooth, and bra? of the back, and terminated below by a broad arched fometimes femilunar, which in fome fubjedb leaves but a bafis inclined backward. The intercoftal mufcles fill up very fmall opening, in others a large opening, and in all the interftices betwixt the ribs, and fo complete the renders the external orifice narrower than the reft of the fides of the cavity; the bafis is the diaphragm, and the cavity. This fold, called hymen, is formed by the union pleura not only covers the whole inner lurface of the ca'of the internal membrane of the great canal with that on vity, but, by forming the mediaftinum, divides it into the infide of the alae, and reprefents a membranous circle two, one on the right hand, the other on the left. of different breadths, and fometimes uneven. This membranous circle is commonly ruptured after M A M M jE. the confummation of marriage; is ouite loft in delivery; and afterwards only fome irregular portions of it remain, The name of mamma?, or breafts, is given to two emiwhich, from their funpofed refemblance to myrtle leaves, more or lefs round, fituated in the anterior and a have been termed earunculae myftiformes. This circle nences the lateral parts of the thorax. may likewife fuffer fome diforder by too great a flux of littleThetoward of the mammae is partly glandular, and partthe menfes, by imprudence, levity, and other particular ly madebody up of fat; or it is a glandular fubftance mixed accidents. portions of the membrana adipoftl, the -cellulous Each fide of the anterior portion of the great canal is with pelliculse of which fupport a great many blood-veffels, covered exteriorly by a thin broad cavernous and vafsu- lymphatics, and ferous or ladtiferous dudts, together lar plexus, called the plexus reriformis of that canal. with fmall glandular molleculae which depend on the forThefe two planes run down on each fide of the clitoris mer ; all of them being clofely furrounded by two membehind the nymphae, and likewife cover the urethra like branes continued from the pelliculas. a collar, before they are fpread on the great canal. The innermoft of thefe two membranes, which is in This plexus is ftridlly united to the mufcular portions a manner the bafis of the body of the mammal is thick commonly taken for accelerators or conftriftors, lying be- and almoft flat, adhering to the mufculus peftoralis matween thefe portions and the lateral parts of the urethra jor. The fecond or external membrane is thinner, formand of the great canal. ing a particular integument for the body of the mam • ma, more or lefs convex, and adhering clofely to the Ikin. Sect. III. Of the Thorax. , The corpus adipofum of the mamma in particular, is a By the thorax, we commonly underftahd all that part fpungy clufter, more or lefs interlarded with fat, or a of the body which anfwers to the extent of the fternum, colle&ion of membranous pellioulae, which, by the partiribs, and vertebras of the back, bpth outwardly and in- cular difpofition of their outer fides, form a kind of memwardly. brane in ihape of a bag, in which all the reft of the corThe thorax is divided into the anterior part called pus adipofum is contained. The anterior or outer por- : commonly the breaft, the pofterior part called the back, tion of this bag, or that which touches the Ikin, is veand the lateral parts called the right and left fides. ry thin ; but that fide next the peftoralis major, is thicks The external parts of the thorax, befides the Ikin and The glandular body contains a white mafs, which is membrana adipofa, are principally the mammae, and the merely a colledtion of membranous du<5ts, narrow at their mufcles which cover the ribs and fill the fpaces between origin, broad in the middle, and which contra# again as • them. In the mammae we fee the papillae or nipples, they approach the papilla, near which they form a kind and a fmall coloured circle, which furrounds them. of circle of communication. They are named dudhis The internal parts of the thorax are contained in the ladliferi. large cavjty of that portion of the trunk, called the The coloured circle or diik is formed by the Ikin, the middle venter, or cavity of the breaft. This cavity inner furface of which fuftains a great number of fmall is lined by a membrane named pleura, and divided glandular ■moHecube. They appear very plainly all over into two lateral cavities by a membranous feptum named the areola, even on the oetfide, where they form little mediaftinum, which is a produdion or duplicature of the flat heights or eminences at different diftances quite reuni pleura. j the circle. . Vcl. I. Numb. 12. 3 4A The