PARTURITION. 
a. But deficiency of fpace in the apertures of the peivis 
occurs much more frequently than excefs. 
A general explanation of the fliape and fituation of the 
pelvis has been given under the article Anatomy, vol. 
5 . p. 54.83 9, 561, 617, 646, 7. And thus, by a know¬ 
ledge of the parts where, and the manner in which, the 
bones of the pelvis are connefted together, we are ena¬ 
bled to explain many uneafy fenfations which women 
have, and many infirmities to which they are liable, at 
the time of pregnancy and after their delivery. It was 
for many centuries a received opinion, that thefe bones, 
though joined together in fuch a manner as fcarcely to 
afford any fufpicion of a reparation, were always feparated 
at the time of parturition ; or that there was a difpofition 
tofeparate, and an aiStual reparation, if the necellity of 
any particular cafe required that enlargement of the ca¬ 
vity of the pelvis which was confequent to it. The de¬ 
gree of feparation was alfo fuppofed to be proportionate 
to fuch neceflity; and if it did not take place, or not in 
fuch a degree as was required, diftending inftruments 
were contrived and ufed to produce or increafe it: and 
upon the fame principle the fedfion of the fymphyfis of 
the ofta pubis, of which we fhall hereafter fpeak, has been 
lately recommended. This opinion ought probably to 
be affigned as. one reafon for the fuperficial notice taken 
by the early writers in midwifery, of thofe difficulties 
which are fometimes found to occur at the time of par¬ 
turition, from the fmallnefs or deformity of the pel vis. 
But this opinion has been controverted by many writers, 
who afiert, that there was neither a feparation nor a dif¬ 
pofition to feparate ; but that, when either of them did 
happen, they were not to be elieemed as common effedts 
attendant on the parturient ftate, but as diieafes of the 
connedling parts. The difputants on each fide have ap¬ 
pealed to prefumptive arguments, and to faffs, proved 
by the examination of the bodies of thofe who have died 
in child-bed, in juftification of their feveral opinions. 
But, though we are not authorized, by the experience 
of the prefent time, to fay that a feparation, or a difpo¬ 
fition to feparate, prevails univerfaliy at the latter part 
of pregnancy or at the time of labour; yet that thefe ef- 
fedls are often, if not generally, produced, may be ga¬ 
thered from the pain and weaknefs at the parts where the 
bones of the pelvis are joined to each other, before and 
after delivery. In fome cafes pregnant women are alfo 
fenfible of a motion at the jundlion of the bones, efpe- 
ciallv at the fymphyfis of the cfla pubis, and the noife 
which accompanies it may be fometimes heard by an at¬ 
tentive by-ftander. We may, however, leave thequeftion 
to be completely fettled by future obfervations. To in¬ 
fill either that the changes occur in every cafe, or that 
they never occur, feems an attempt to fupport opinions 
repugnant to daily experience. For no perfon, who has 
been converfant in the diffedlion of women who have 
died in childbed, can have wanted opportunities of feeing 
every intermediate ftate of thefe parts ; from a feparation 
in which the furfaces of the bones were loofened, and at 
a confiderable diftance from each other, to that in which 
there was not the leaft difpofition to feparate. Thus it 
appears, that the degrees of feparation at the junctions of 
the bones of the pelvis to each other may be very diffe¬ 
rent ; and that, when it takes place beyond a certain de¬ 
gree, it is to be confidered as morbid. “Several cafes of 
this kind, which have occurred in my own praftice,’’ 
fays Dr. Denman, “and many for which I have been 
confulted, have laid me under the neceffity of confider- 
ing this fubjeifl with the mod ferious attention ; and I 
prefume that it may be produced by two caufes ; firlt, 
a fpontaneous difpofition of the connecting parts ; 
fecondly, the violence with which the head of the child 
may be protruded through the peivis.” Of a feparation 
from each of thefe caufes the dodlor then gives an ex¬ 
ample, to prove the fad, and to ffiow its confequences. 
Thefe cafes, however, we fhall not tranfcribe ; becaufe 
we are of opinion that, if the part does yield during par- 
691 
turition, it is in a very final 1 degree, and foon recovers 
itfelf by reft; or, if it yield more confiderably, it is at¬ 
tended either with fatal confequences or with incurable 
lamenefs. We (hall therefore proceed to confider the 
pelvis according to its (unyielding) dimenfions. v 
The form of the fuperior aperture of the pelvis has 
been defcribed by fome as triangular, and by others as 
oval, with the wideft part from one fide to the other. 
But the inferior aperture, independent of the ligaments 
and foft parts, cannot be laid to refemble any known or 
general form, on account of its irregularity, though the 
wideft part is from the inferior edge of the fymphyfis to 
the point of the os coccygis, allowing for the regreffive 
motion of that bone. The dimenfions of the fuperior 
aperture of the pelvis, from the upper part of the facrum 
to the upper edge of the fymphyfis, are generally Hated 
to be rather more than four inches; and between the two 
fides they fomewlnat exceed five. Of the dimenfions of 
the inferior aperture it is difficult to form a judgment ; 
but, if the ligaments are preferved, it may be faid that 
the proportions are reverfed, the narrowed part being on 
each fide. But in the form and dimenfions of the pel¬ 
vis, in different women, there is an endlefs variety, not 
depending upon any alteration which may be produced 
by difeafe. The depth of the pelvis, from the upper 
part of the facrum to the point of the os coccygis, is 
about five inches ; but this will be increafed when the 
latter bone is prefled backwards. From the margin of 
the pelvis to the inferior part of the obtufe procelies of 
the ifchia the depth is about three inches, and at the fym- 
phifis about one and a half. It appears that the depth 
of the pelvis, at the pofterior part, is rather more than 
three times the depth at the anterior; and that there is a 
gradual change between the two extremes, if we admit 
the ligaments to make a part of the outline of the infe¬ 
rior aperture. 
Of the diftortion of the peivis there are two general 
caufes. The firlt is that difeafe incident to children in 
the very early part of their lives, known by the term ra¬ 
chitis, rickets, which preventing the bones from acqui¬ 
ring their due ftrength or fufficient firmnefs to fupport 
the weight of the l'uperincumbent body, they bend in 
different directions and degrees, according to their weak¬ 
nefs and the weight impofed upon them. The fecond is 
a difeafe which may occur at any period of life, and from 
its effedl is called ojleqfarcojis , or mollifies ojjium, foftnefs of 
the bones. It is far lei's frequent than the rachitis, but 
more dreadful in its confequences; which no medicine 
hitherto tried has had fufficient efficacy to prevent or to 
cute. In this difeafe the offific matter is not thought to 
be diffolved or altered, but to be re-abforbed from the 
bones into the conftitution, and carried out of the body 
by fome common emundlories ; or depofited upon fome 
other part where it is ufelefs or prejudicial. The bones, 
thus lofing the principle of their liability, become loft, 
according to the degree and continuance of the difeafe ; 
are unable to fuftain the weight of the body, and change 
their natural forms, in proportion to their weaknefs ; fo 
that in fome inftances the moll dillorted and frightful ap¬ 
pearance of the whole body hath been exhibited. The 
effedl of either of thefe difeafes is not indeed confined to 
the pelvis ; yet it is fcarcely poffible that either of them 
Ihould exift for any length of time without producing 
their influence upon it. 
The pelvis is more commonly dillorted at the fuperior 
aperture than at any other part. This is particularly oc- 
cafioned by the natural projedlion of the upper part of 
the facrum, and the lowed of the lumbar vertebras ; 
though, in very bad cafes, a confiderable deviation from 
their natural pofition is given to leverai of the vertebras. 
Should a difeafe exift in the conftitution which is capable 
of weakening the bones, it will not appear extraordinary 
that the facrum Ihould be dillorted, if we recolledl, that 
its texture is originally fpongy ; that it fupports, both 
in the eredt and fedentary pofition, a great part of the 
4 weight 
