24 OF THE PELVIS. 



37. The abdominal basin constitutes part of the belly. Of an 

 elliptical form, largely notched in front, where it corresponds to the 

 hypogastrium, notched also behind, in order to receive the lower end 

 of the spine, this cavity is composed of the tMro internal iliac fossae, 

 which belong to the coxal bones, as well as to the lesser wings of 

 the sacrum, and which are occupied by the sigmoid flexure of the 

 colon on the left, the crecum on the right, and by some folds of the 

 small intestines on both sides. 



38. The lesser basin may be considered as part of a canal larger 

 in the middle than at its two extremities, curved anteriorly, and des- 

 tined to contain the internal genito-urinary organs, the rectum, and 

 the hypogastric and sacral vessels and nerves. In order to obtain 

 a clearer idea of it, it is well to follow the advice of M. Chaussier, 

 that is to say, to remove the greater basin by a horizontal section 

 with a saw. Like the external surface, it may be divided into four 

 regions, and circumscribed in the same way, always excepting the 

 lateral regions, which leave the internal face of the ilium above 

 them. 



39. The anterior region of the lesser basin, very greatly notched 

 below by the pubic arch, slightly convex from above downwards, 

 and concave transversely, comprises the posterior face or the bodies 

 of the pubes, of the ischio-pubal rami, and of the obturator mem- 

 branes. We may remark, 1. On the median line a perpendicular 

 crest, more or less salient, formed by the posterior part of the sym- 

 physis pubis; 2. Outwardly, the internal obturator fossa, surmounted 

 by a canal, (and not a simple hole,) oblique from behind forwards, 

 and from without inwards; through this, which is called the sub-pu- 

 bal or obturator canal, the obturator vessels and nerves proceed from 

 the interior of the pelvis to the inner side of the thigh. 



40. The posterior region, very much excavated, is represented by 

 the anterior surface of the sacrum, of the coccyx, and of the root of 

 the sacro-ischiatic ligaments. 



41. The lateral regions, formed in front by the internal face of 

 the cotyloid portion and the rest of the ischium, behind by the inner 

 face of the sacro-ischiatic ligaments, are largely opened by the two 

 sciatic holes. Of these two openings, one, superior and the largest, 

 is of an oval shape, and gives passage from within the pelvis, 1. To 

 the pyramidal muscle, which is inserted into the great trochanter; 

 2. To the great sciatic nerve, which proceeds to be distributed on 

 the back part of the thigh, the outer and back part of the leg, and 

 to the whole foot; 3. To the gluteal artery, and to the internal pubic 

 vessels and nerves: the other, inferior, much smaller, of a triangular 

 shape, is filled by the internal obturator muscle, which proceeds to 



