v.] SKELETON OP LOWER LIMB. 179 



strongly marked prominence called the posterior inferior 

 spinous process, beneath which the border is deeply excavated 

 and concave. 



The inner surface of the ilium is concave, forming the iliac 

 fossa, and at its hinder part is a rough irregular space for 

 articulation with the sacrum. The ilium forms about the 

 upper third of the socket for the thigh-bone. 



sy 



FIG. 153. INNER SIDE OF RIGHT Os INXO.MINATUM OF MAN. 

 at, anterior inferior spinous process ; as, anterior superior spinous process ; an, 

 auricular surface ; c, crest ; i, ischium ; il, iliac fossa ; p, pubis its horizontal 

 ramus ; pi, posterior inferior spinous process ; ps, posterior superior spinous 

 process ; s, spine of the ischium ; sy, part of the pubis which abuts against its 

 fellow of the opposite side to form the pubic symphysis. 



$, or pubic bone, forms the inner part of the thigh- 

 socket, joining the ilium above, and at its junction con- 

 tributing to form the ilio-pectineal eminence. It thence pro- 

 ceeds horizontally inwards (as a band of bone flattened from 

 without inwards, called the horizontal ramus) till it meets with 

 its fellow of the opposite side, when it turns sharply down- 

 wards. The junction of the two pubes is termed the sym- 

 physis, and the part of each pubis next the symphysis is 

 sometimes called the body / thence the pubis runs outwards 

 and downwards (as a flattened band, similar to the horizontal 

 ramus, with which it forms an acute angle) till it meets the 

 ascending ramus of the ischium. 



The ischium forms the outer and lower part of the thigh- 

 socket, and indeed of the whole t)s innominatum. The body 

 of the ischium forms about two-fifths of the socket for the 

 thigh, which cavity is situated on its outer side. The body is 

 broad, and sends from its posterior outer margin a large sharp 



N 2 



