SYMPHYSIS PELVIS — OBTURATOR MEMBRANE 



191 



quadrilateral sheet which completes the lateral pelvic wall. Its upper border is 

 attached to the border of the sacrum and the transverse processes of the first and 

 second coccygeal vertebrae. Its lower border is attached to the superior ischiatic 

 spine and tuber ischii. Between these it bridges over the ext(n-nal border of the 

 ischium and completes the lesser sciatic foramen. The anterior border is concave, 

 and completes the greater sciatic foramen. The posterior border is fused with the 

 vertebral head of the semimembranosus muscle. 



The ilio-lumbar ligament (Ligamentum ilio-lumbale) is a triangular sheet which 

 attaches the ends of the lumbar transverse ])rocesses to the ventral surface of the 

 ilium below the attachment of the longissimus muscle (Fig. 184). 



enlral s(icro-ih(i( iK/dmcnt 



1 E.rtmuil angle 

 of ilium 



Sdcro-iliac articidntion 



Ilio-peciineal 

 eminence 



Depression for origin of inner tendon of 

 hiccps femoris 



Posterior part of trochanter mojor 

 Anterior part of trochanter 

 maj(fr 

 X 



Trochanter minor 



Fig. 153. — Left Os Cox.e and Adjacent Parts of Sacrum and Femur of Horse. (After Schmaltz, Atlas 



d. Aiiat. d. Pferdes.) 



SYMPHYSIS PELVIS 

 The symphysis pelvis is formed l)y the junction of the two ossa coxarum at 

 the ventral median line. In the young subject the l)ones are united by a layer of 

 cartilage; in the adult the latter is gradually replaced by bone, the process beginning 

 in the pubic portion and extending backward. The union is strengthened by white 

 fibrous tissue above and below, and a transverse band also covers the anterior border 

 of the pubis (pecten). No appreciable movement occurs even before synostosis 

 takes place. 



OBTURATOR MEMBRANE 

 This (Membrana ol^turatoria) is a thin Xslyqv of fibrous tissue which covers the 

 obturator foramen, leaving, however, a passage (Canalis obturatorius) for the 

 obturator vessels and nerve. 



