208 



PELVIS. 



sial surfaces forwards, by the action of 

 the adductors and obturator externus. The 

 lateral curvature of the sacrum is consider- 

 ably flattened out, and also the cotylo-sa- 

 cral rib of the ilium. The sacro-iliac joints 

 are each opened in front, for the space of about 

 half an inch, stretching the anterior ligaments. 

 The great space between the pubes is evidently 

 obtained by the flattening of the linea inno- 

 minata, as well as by the shortening of the 

 innominate bones, in breadth, and their abnor- 

 mal vertical or wall-sided position. The 

 resulting diameters are ; antero-posterior, 

 from the sacral promontory to the inter-pubic 

 ligament, 4- inches ; the inter- cotyloid, 6 

 inches ; and between the sciatic tuberosities, 

 6^ inches. This condition, according to Meckel, 

 is rarely met with without an analogous con- 

 genital fissure in the bladder and walls of the 

 abdomen. Walter, however, mentions one 

 case. * 



Other congenital abnormalities of the pelvic 

 bones are mentioned by Otto and Rokitansky. 

 In the siren formation, the coccyx and lower 

 extremities are entirely wanting, and the 

 lateral parts of the pelvic bones are fused 

 together, the outlet of the pelvis being nearly 

 completely closed, and the parts presenting 

 the appearance of the pelvis as we have seen 

 it in the Cetaceans and Fishes. Their deve- 

 lopment seems to have been arrested at 

 that period of foetal life in which this condi- 

 tion is normally, though transitorily, present. 

 In some monstrosities, the sacrum also is 

 wanting, or one or both the innominate bones, 

 with the correspondig lower extremities ; or 

 these parts may be stunted or coalesced. 



Influence of hip-joint disease upon the pelvis. 

 Caries and necrosis of the pelvic bones, 

 although sometimes resulting idiopathically, or 

 from bedsores and abscesses in the muscular 

 sheaths or lymphatics, } r et chiefly occur as the 

 consequences of coxa/gia, and have a tubercu- 

 lar origin. The formation of false acetabula 

 and the other pathological results of this di- 

 sease or accidental malposition belong more 

 especially to the pathology of the Hip-joint. 



A preparation of one of these in the Hun- 

 terian Museum may be, however, appropriately 

 described in this place, inasmuch as it would 

 produce, if occurring in a parturient female, an 

 obstruction to the foetal head, analogous to an 

 exostosis. The head of the femur has become 

 displaced into the obturator foramen, and 

 about it an osseous deposit has taken place, 

 apparently in the obturator membrane, which 

 forms a smooth dome-like projection into the 

 pelvic cavity, corresponding in size to the head 

 of the femur. The subject is a male one, and 

 the carious and light condition of the bones 

 and the irregular ossific projections, indicate 

 the results of disease. 



An interesting change in the position of the 

 pelvic bones after hip-joint disease, is de- 

 scribed by Rokitansky. f 



* Von der Spaltung der Schambeine. Berlin, 

 1782. 



f Pathological Anatomy, p. 259. Sydenham 

 Society's translation. 



The dislocation of the femur upwards, which 

 is commonly the result of coxalgia, is followed 

 by a wasting of the innominate bones, especi- 

 ally of the ilium. They assume a more ver- 

 tical direction, and, at the same time, their 

 inclination to the spine, as well as the lumbar 

 curve, is considerably increased. 



If this condition be present on both sides, 

 there is general enlargement of the pelvic 

 cavity, due partly to a general attenuation 

 of the bones, causing the disappearance of 

 the projections at the pectineal eminences, 

 the sacro-iliac joints and the cotyloid walls, 

 and partly to a flattening out of the linea in- 

 nominate. The ischia become dragged out- 

 wards and separated, the pelvic cavity shal- 

 lower, and the sub-pubic angle more obtuse. 



The last result is attributed by Hiilshof to 

 the dragging of the rotator muscles, from the 

 displaced femur on the sciatic tuberosities, upon 

 which the support of the trunk mainly falls in 

 this condition of the joint. In the pelvis of a 

 woman mentioned by Dr. Hull, however, in 

 whom both the femurs had been dislocated 

 backwards, the transverse diameter of the brim 

 was diminished to 4 inches, and the antero- 

 posterior diameter of the outlet was diminished 

 to only 2 inches, from the tilting forward of 

 the lower part of the sacrum, or rather pro- 

 bably, from the turning of the lower part of 

 the innominate bones backward by the dis- 

 placed femurs, acting on the axis of the sacro- 

 iliac joints. 



If the disease be one-sided only, as is most 

 commonly the case, and the diseased joint 

 be much used, the tuber isc/iii of that side 

 becomes everted, the innominate bone bent 

 outwards, the distance from the pubic sym- 

 physis to the anterior superior iliac spine 

 lessened, and that side of the pelvic cavity 

 enlarged. The pelvic cavity is, on the other 

 hand, contracted on the sound side, towards 

 which also the spinal curvature inclines, from 

 the principal support of the body falling on 

 that side. When ankylosis has taken place, 

 the innominate bone is bent outward at the 

 acetabulum, in the osseous cicatrix ; the ilium 

 is placed more inwards and forwards, and the 

 ischium inwards and backwards ; and while 

 the pubic symphysis is drawn towards the 

 diseased side, the sacral promontory is turned 

 to the healthy side of the pelvis. In some 

 instances, the pelvic inclination is less, instead 

 of greater, on the diseased side, which is also 

 raised higher than the other. This variation 

 is attributed by Guerin to the action of the 

 psoas and iliacus muscles, which sometimes 

 in these cases impress a deep furrow upon 

 the iliac wings, over the edge of which they 

 play. There is no doubt, that the posture to 

 which the patient may have been most ac- 

 customed, has a great effect in producing such 

 differences, as already explained in the fore- 

 going pages. 



FRACTURF.S AND DISLOCATIONS ofthepelvic 

 bones. The sacrum, according to Boyer,is less 

 frequently found fractured than the other 

 pelvic bones, because of its .thickness, strength, 



