470 



THE PELVIS. 



SECTION III. 

 THE PELVIS. 



The pelvis is situated at the lower portion of the trunk, 

 and is composed of four bones the sacrum, coccyx, and 

 two ossa innominata. The two former have been examined 

 along with the spine. It only remains, therefore, to speak 

 of the latter. 



Os-innominatum. This bone is situated at the lateral 

 and anterior portions of the pelvis, and in the adult is 

 A FIG. 142. B composed of a sin- 



gle piece ; but in 

 the young subject 

 consists of three : 

 the ilium, iscliium, 

 and pubis. 



The ilium is sit- 

 uated at the su- 

 perior and outer 

 portion of the pel- 

 vis, and is the 

 largest of the 

 three bones composing the innominatum. This bone is com- 

 monly called the hip, or haunch bone. It is somewhat triangu- 

 lar, broad and flat. It is divided into a body, ala, and. pro- 

 cesses. The body is the lower narrow portion, forming the 

 upper and outer part of the acetabulum. It has, anteriorly, a 



FIG. 142, A represents an exterior view of the Os-innominatum. 1 Crest 

 of Ilium. 2 Anterior superior spinous process. 4 Anterior inferior spi- 

 nous process. 5 Notch for the psoas-magnus, and iliacus internus. 6 Ileo- 

 pubic spine. 8 Obturator foramen. 9 Angle of pubis. 11 Descending ramus 

 of pubis. 12 Tuberosity of ischium. 13 Lesser sciatic notch. 14 Spine of 

 the ischium. 15 16 Greater sciatic notch. 17 Posterior inferior spinous pro- 

 cesses of ilium. 18 Rough surface. 19 Posterior superior spinous process. 

 21 Dorsum of the ilium. 



FIG. 142, B represents an inner view of the innominatum. The figures 2 4 

 8 9 11 12 13 14 16 correspond to similar points as in Fig. A. 3 Groove for 

 obturator vessels and nerves. 20 Posterior superior spinous process. 23 

 Posterior inferior spinous process. 22 Fissure between posterior processes. 

 21 Venter of ilium. 24 Svmphysis pubis. 



