| XXX | (262) | XXX |
-A 262 ANATOM Y. Part VI. It contains a great number of fingl or folitary glands; infertion. is in the middle tendon of the tranfverfalis ureand it is always moiftened by a mucus of different eon- thrae; and they have likewife fome connexions, to other fiftences.difcharged by thefe glands or follicuii. Near the extremity of this inteftine, the rugs or mufcles of the urethra. ani are broad, thin, mufcular portion*, folds become in a manner longitudinal; and at laft, to- fixed1 hebylevatores one extremity of their flefhy fibres round the wards the circumference of the inner margin 0/ the anus, concave fide of the inferior portion of the pelvis, from they form little bags or femilunar lacunae, the openings the fymphyfis of the offa pubis, beyond the fpine of the of which are turned upward, toward the cavity of the The other extremity of thefe fibres runs inteftine. Thele lacunae are fomething like thofe at the ifehium. down on each fide behind, and under the curvature of lower extremity of the cefophagus, or .upper orifice of the end of the re&um, where they meet together, and the ftomach. unite from the bafis of the os coccygis all the way to the At length the extremity of the return contracts, and margin of the anus. terminates by a narrow orifice called the anus, the Tides We ought likewife to remark, that the margin or edge of which are difpofed in clofe folds or gathers. This of the anus is formed by the union of the Ikin and epiextremity of the inteftine has feveral mul'cles belonging dermis wfth the internal coat of the rectum ; fo that the to it, fome of which furround it like ffphindters, the reit moft fuperficial portion of that coat feems to be a contiare broad flelhy planes inferted in it, and which being nuation of the epidermis. likewife fixed to other parts, fuftain it in its natural fituation, and reflores it to that fituation when difiurbed MESENTERIUM & MESOCOLON. by the force neceffary for the exclufion of the faeces. Thefe latter mufcles are.termed levatores ani, the firfl This great bundle of inteftines is not left to move at go by the general name of fphin&ers. random in the cavity of the abdomen; but artfully bound Thefe fphindtcrs are three in number, one intefKnal down by a membranous web, which prevents the inteftior orbicular, and two cutaneous or oval; whereof one is nal convolutions from being intangled in each other, and large, fuperior, and internal; the other final], inferi- from being twifted or compreffed in all their different ways or, and external. of meeting; and yet allows them a gentle floating, but The intehinal or orbicular fphindter of the anus, con- limited motion. fills merely in an augmentation of the inferior portion This web is diftinguiihed into two portions; one of of the flelhy fibres of the extremity of the redtum. which, being very broad and very much plaited, connects The cutaneous ligament goes out anteriorly, from the fmall inteftines ; the other, which is long and incurthe extremity of the cs coccygis. It is very fiender, vated, does the fame office to the greater imeftines. and divides into two portions at the orifice of the anus, Thefe two portions are in reality only , one and the which run into the mernbrana adipofa, and are inferted fame continuation of the membranous lamina of the periin the Ikin on each fide of the anus, by a kind of expan- tonteum doubled back upon itfelf, and they are diftinfion ; and continuing to divaricate, they are loft on the guiffied only by their breadth. Taken both together, two fides of the peritonaeum. they form a kind of fpiral roll, more or lefs plaited in The interoffeous ligament of the offa pubis is a very its circumference. The firft portion has retained the ftrong triangular membrane, fixed by two of its edges in name of mefentery, the other is termed mefocolon. the inferior rami of thefe bones, all the way up to their The mefentery begins at the laft incurvation of the common fymphyfis. The third edge, which is the loweft, duodenum, and runs obliquely from left to right, along is loofe ; and this whole membrane, the middle of which the vertebra? of the loins. In this fpace, the membrais perforated by a particular hole, is ftretched very tight nous portion of the peritonaeum is detached on both between the two bones, and under their cartilaginous hands, produces a duplicature by two elongations or arch, to which it adheres very clofely. particular lamina? applied to each other, and thu,s forms At the lower part of this interoffeous ligament, along the mefentery. its whole lower or loofe edge, lies a digaftric mufcle, It is narrow at its upper and lower parts, but chiefly fixed by its two extremities in the rami of the offa pubis, at the upper. The middle portion is very broad, and its middle tendon lying on the middle of the edge of the the edge of it next the inteftines is every where very ligament. much plaited. Thefe plaits or folds are only waving inThe cutaneous fphin&ers have each an anterior and flexions, fuch as may be obferved in the edge of a piece pofterior infertion, ending both ways in a kind of point, of ffiamoy, which has been often drawn through the finand comprehending the orifice of the anus between their gers. They make this edge of the mefentery very long, middle portions. and they run through about one third of its breadth. They are diftinguifhed from each other by their fitua- The two laminae are joined together by a cejlular fubtion, by their fize, ami by a kind of white cellular line. ftance, which contains 'glands, veflels, and nerves; and The greateft of the two appears to be double, and the in fome fubje&s a great quantity of fat, which keeps the fmalleft lies neareft the Ikin, and adheres moft clofely two lamina: a diftance from each other. to it. Along the whole circumference of the mefentery, the They are inferted backward, partly in the apex of the two laminae are naturally feparated, and applied to the os coccygis, and partly in the contiguous portion of the two fides of the final! inteftines, which they inveft by cutaneous ligament of that bone. Forward their chief their union, or rather reciprocal continuation on th» great curvature
