116 



PELVIS. 



line of an irregular curvaarre, commencing 

 posteriorly at the centre of the great sciatic 

 notch, and, passing upwards and forwards, 

 terminates in the crest a little posterior to the 

 anterior superior spine. This is the superior 

 curved line (2) (posterior of Cruveilhier). 

 Below this is another line of a like character, 

 the inferior curved line (3) (the anterior of 

 Cruveilhier); which, commencing an inch be- 

 low the'other in the sciatic notch, gradually 

 diverges from it, and terminates anteriorly at 

 the inferior spinous process of the ilium. The 

 surface presents numerous small circular open- 

 ings for the admission of the nutritious vessels 

 of the bone, all of which have a direction 

 downwards towards the articular surface?. 



About an inch and a half below the inferior 

 curved line is a large articular cavity for the 

 reception of the head of the thigh bone, which 

 is named the acetabulum, or cotyloid cavity, 

 KorvXn, a cup ; and dcoc., like (4). This is a 

 perfectly hemispherical excavation of about two 

 inches diameter in the full grown male, and cir- 

 cumscribed by a rough irregularly raised brim 

 or circular border, to which is attached the 

 circumferential fibro-cartilage or cotyloid liga- 

 ment of the hip-joint. When the bone is pro- 

 perly placed, as in the articulated skeleton, the 

 axis of this cavity is directed outwards and 

 a little downwards for the better adaptation of 

 the femur ; and to this end the posterior part 

 of its circumference is much thicker and more 

 prominently elevated than the anterior. Su- 

 periorly it is still more evidently prolonged 

 outwards at the point where the before men- 

 tioned thick vertical ridge of the ilium springs 

 from it. Inferiorly the border is interrupted 

 for the space of an inch by the cotyloid notch 

 (5), to the edges of which are attached the 

 transverse and interarticular ligaments of the 

 hip-joint, and which is continued into the cen- 

 tre of the cavity by a rough depression or fossa, 

 for the reception of some lubricating glands 

 and the interarticular ligament connected with 

 the femur. The bottom of the notch is on 

 the same plane as that of the depression, and 

 affords an entrance for the vessels and nerves 

 supplying the joints. The remainder of the 

 cavity is a smooth and even surface, uniformly 

 concave and circular, which is covered in the 

 fresh state by a cartilage of a semilunar shape. 

 The broadest part of this surface is above 

 where the superior border projects. The pos- 

 terior extremity is prolonged into a lip which 

 a little overhangs the notch posteriorly, and 

 terminates exactly opposite to the broadest 

 part of the overhanging superior margin. The 

 anterior extremity is the narrowest, being 

 notched slightly by the groove below the an- 

 terior inferior iliac spine on the anterior bor- 

 der of the bone before mentioned. At the 

 bottom of the cotyloid fossa may be traced 

 two lines arranged in the shape of a T, the 

 lower limb of which divides the cotyloid 

 notch into nearly equal portions. These mark 

 the foetal division of the bone into three por- 

 tions, of which the ilium contributes the two 

 superior fifths, the ischium the infeuor pos- 

 terior two fifths, and the pubis the remaining 



anterior inferior fifth, to the formation of the 

 cotyloid cavity. Externally, the brim of the ace- 

 tabidum is convex, rounded, rough, and marked 

 above and behind by the attachment of the 

 capsular ligament of the hip-joint ( 6). It 

 is here perforated by numerous foramina 

 for the admission of nutritive vessels. It is 

 much better pronounced above and behind, 

 where it presents a broad, thick, convex sur- 

 face, than in front where it is shallow, thin, 

 and slightly depressed. The points where 

 this difference is indicated are, the inferior 

 spine of the ilium above, and the cotyloid 

 notch below. 



Springing from the cotyloid cavity are two 

 branches of bone ; one from the inferior part, 

 thick, massive, directed downwards and back- 

 wards called the descending ranntx or body of the 

 ischium(p} ; and the other, from the anterior 

 part, slighter in structure, and directed obli- 

 quely downwards, forwards, and inwards in the 

 same plane with the ilium, called the horizontal 

 ramus or body of (he pubis (7). These are each 

 prolonged at their further extremities into 

 flattened tapering processes, which, alter- 

 ing the original direction of their respective 

 portions of bone, one ascends obliquely in- 

 wards, and the other descends obliquely out- 

 wards, to unite with each other midway, at a 

 point marked by a slight transverse line. They 

 are named respectively the ascending ramus of 

 the ischium (r), and the descending ramus of the 

 pubis (*).* Together they form the inferior 

 border of the innominate bone, and complete 

 the formation of a large oval opening, situated 

 immediately below, and a little internal to the 

 cotyloid cavity, having its long axis directed 

 obliquely downwards and outwards, and called 

 the obturator or thyroid foramen (o) Su/oeoc, a 

 shield; and d$oq, like. The edges of this 

 opening are thin, bevilled off, and rough, for 

 the attachment of a fascial ligament which 

 closes the opening, and are formed entirely by 

 the ischium and pubes. The external edge, 

 instead of meeting the internal superiorly, is 

 continued inwards in front of it, along the 

 superior ramus to the spine of the pubes 

 before described, forming a prominent rib of 

 bone of a triangular shape (</), its base abut- 

 ting on the cotyloid cavity. This rib is con- 

 vex vertically, and concave laterally. Between 

 it and the internal edge of the thyroid fora- 

 men is left a groove, called the sub-pubic or 

 obturator groove (/), for the passage of a nerve 

 and vessels, and which has a direction down- 

 wards and inwards. The junction of the 

 horizontal and descending rami of the pubis 

 is called the angle of the pubis, and it is hol- 



* There has been much confusion in the applica- 

 tion of names to these bones, the term body of the 

 pubis is applied by some to the angle, and by others 

 to the cotyloid portion only. The term body is 

 confined also by some to the acetabular part of the 

 ischium. The expressions horizontal and descending 

 rami of the pubis and ascending ramus of the 

 ischium were applied before a true knowledge of the 

 pelvic obliquity was obtained. The former would 

 probably be well superseded by the words superior 

 and inferior, and those applied to the ischial rami 

 by anterior and posterior, or greater and lesser. 



