INTEGUMENTS. 



as the mufcles do ; and they are of the fame nature with 

 .what we obferve in mucous furfaces, particularly in the 

 ftomach, when the contiguous mufcular plane is contraftcd. 

 Hence their diredion is always perpendicular to that of the 

 fubjacent mufcles, whofc fibies they cut at right angles. 

 As the motions of thefe parts in the human countenance are 

 much influenced by the pafficns, the wrinkles and irre- 

 gularities in the fnce are highly important in a phyfiognomical 

 point of view. The repeated aftions of particular mufcles, 

 under the habitual impreflion of particular paffions, pro- 

 duce permanent lines, which give the character of the in- 

 dividual. 



2. Other wrinkles arife from the motions of parts, but not 

 from thofe of the fubjacent mufcles : fuch are thofe of the 

 palm and fole. Here there is no fub-cutaneous mr.fcle ad- 

 hering to tiie flcin, except the palmaris brevis, which has no 

 fliare in producing the folds, where the flcin is habitually 

 modified by the flexion of the organ. To this clafs belong 

 the imprefiions at the articulations of the phalanges. In 

 the palm there are three principal ones : at the balis of the 

 thumb, produced by the motion of oppofition of that or- 

 gan, at the front of the palm, by the flexion of the iingers, 

 and in the middle of the palm. The cutis forms folds in 

 thefe dcprefled lines when the palm is rendered hollow. 

 Numerous other fmall folds, correfponding to lefa marked 

 and frequent motions, cut the former at various angles. 



In the back of the foot and hand we obferve numerous 

 wrinkles at each articulation of the phalanges, when they 

 are extended : they difappear on flexion, and arife from the 

 fkin being loofer and more copious in thefe parts to accom- 

 modate the motions. There are analogous folds at moft of 

 the articulations, but they are lefs ftrongly marked, be- 

 caufe the ik'm is lefs adherent to the neighbouring organs. 

 Over the whole trunk, on the arm and fore-arm, the leg 

 and thigh, no depreflions are obferved except thofe produced 

 by mufcular prominences. 



3. A third kind of wrinkles, or rather of cutaneous im- 

 prefiions, which are very ineonfiderable, occurs particularly 

 in the fole and palm, where they are eaiily dillinguillied 

 from the foregoing. They indicate the rows of papillae : 

 and nothing of the kind occurs on the furface of the trunk. 



4. Laftly, there are the wrinkles of old age, the nature 

 of which is quite different. When the fub-cutaneous fat has 

 begun to difappear, the fl<in is too large for the parts which 

 It covers : it lofes its contratlility by age, and cannot there- 

 fore accommodate itfelf to the altered bulk of parts. Thus, 

 where there was moll fat, as in the face, tlie wrinkles are 

 TOoft ftrongly marked. When young perfons are fuddenly 

 emaciated, the fkin contradls, and no wrinkles eniue. 



The internal furface of the flcin correfponds every where 

 to the cellular tilTue, which is loofe on the trunk, the thighs, 

 arms, &c. and more denfe on the cranium, hand, &c. In 

 mod animals, a mufcular plane, named panniculus carnofus, 

 and analogous in its form to that which is every where 

 connefted to the mucous membranes in man, feparates the 

 (ki[i from the other organs, and imparts to it various motions. 

 Traces of fuch a llrutture occur in a few inftances in man, 

 as in the latifiimus colli, the cpicranius, and the mufcles of 

 the face. 



The cellular tilTue connefts the cutis to mufcles almoft 

 univerfally in the trunk ; but it has nothing to do with the 

 motions of thefe mufcles, and receives from them no fen- 

 fible influence. It ie fcparatcd from the mufcles in the 

 limbs by aponeurofes. Many vcflcls purfue their courfe 

 under it : large veins may be obferved through its fubftance; 

 numerous arterial ramifications are dillributed on its fur- 

 face ; and nerves arc found among thefe. 

 7 



Orgainzaiton oftht Dermoid Syfiae. 

 I. Proper Tifue of this S_}Jlem.—Thk comprehends, 

 ift, thecorion; 2dly, the rete mucofum ; and, 3dly, the 

 papilla: or villi. The corion is the elTential part, which de- 

 termines the thicknefs and form of the flcin : the rete mu- 

 cofum is not very difl.ind from it ; and the papilla; manifeftly 

 grow out of it. 



The corion is always white in the human fubjeft. Its 

 thicknefs varies coufidcrably. In the head it polTefTes op- 

 pofite charafters on the cranium and the face : in the former 

 it is very thick and denfe in its texture, in confequence of 

 the numerous hairs which traverfe it : in the latter it is every 

 where thin and delicate, but more particularly in the eyelids 

 and lips. On the poilerior part of the trunk, and efpe- 

 cially along the back, its thicknefs is nearly double that 

 which it has in front, where it is nearly uniform in the 

 neck, chefl;, and abdomen. We mull except, however, the 

 penis, fcrotum, labia, and breafls, where its texture is much 

 thinner. The corion is nearly of equal thicknefs in the 

 flioulder, arm, and fore -arm ; in the hand its thicknefs is ra- 

 ther increafed, and more fo in the palm than on the back. It it 

 generally much thicker on the .thigh and leg, where there 

 are more bulky mufcles than in the arm and fore-arm. It 

 grows thicker in the foot, but lefs fo in the dorfal than in 

 the plantar region, which is the thickeft part of the fyftem. 

 The relation of its fundlioas to the various degrees of 

 thicknefs obferved in the hand, foot, and cranium, may be 

 eafily underllood ; but in other parts we do not clearly fee 

 the reafon of thefe differences. 



It is generally thinner in v.omen than in men, fo as to 

 prefent a fenlible difference when the two are contrailed in 

 any region of the body. 



In order to examine the interior ftruclure of the corion, 

 it fliould be carefully feparated from the cellular and adipous 

 tiffue, to which the inner furface adheres more or lefa clofely ; 

 we (hall then find that furface differently difpofed in the dif- 

 ferent regions. 



1. In the fole and palm we fee an infinite number of 

 whitifli fibres, fliining hke thofe of an aponeurotic nature, 

 detached from the inner furface of the flcin, decuffating each 

 other in every direftion, leaving, particularly towards the 

 heel, numerous areolte of different fi/.es filled with fat, and 

 gradually loll in the fub-cutaneous tiffue. Hence there is 

 not the fame mobility of the flcin over the covered parts, 

 on thefe furfaces, as in mod other fituations ; an arrange- 

 ment well fuited to the fundlions of prehcnfion and fupport 

 belonging to thefe parts. 



2. The cutis of other parts of the body has thefe fibres 

 much lefs diflind, not interwoven with the cellular tiffue, 

 and feparated by fmaller areola : hence it is much loofer, 

 and more eafily diffeclcd from the fubjacent parts. The 

 areola; reprcfent a vail number of openings placed irre- 

 gularly by the fide of each other, and lodging fmall maffe* 

 of fat : when thefe are carefully removed very fenfible 

 vacuities are left. The fibres, which form them, are fuffi- 

 ciently clofe to give the appearance of an uniform ftrufture 

 perforated by numerous apertures. Thefe areola; arc very 

 favourable to the adlion of the tanning principle, which is 

 introduced through them to the corion much more ef- 

 feftually than it can penetrate on the oppofite fide. Bichat 

 afcertained this point by a dired experiment on the human 

 flcin. Cliaptal has obferved that the epidermis is a real ob- 

 ftacle to the aAion of tanning, and that its removal, with 

 that of the hair, is an cflential prehminary for this reafon : 

 but that the hide, even when thus prepared, is affetted much 

 more eaiily on the inner than on the outer fide. 



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