. / A' /'/I 7V./ '//( ).\S. /./<;. M/A'.V AS 



457 



(lstc<>/t>gicti/ ( : nits.- Tlu: s.icruni and ilium. 



I'tirts. Auricular surfaces (if the sacrum and ilium. 

 '/r. Superior gluteal, sacral plexus, first and second sacral . 



mood-supply. (lluieal, ilio-lumbar, and lateral sacral artei 



Morphologically, -elicit is tliat part of the sacrum that articulates ;,.//// the 

 auricular part of the ilium f 



It is the result of a peculiar modification of the costal elements of tin first 

 three sacral vertebra . 



A T ai>ic anii locate lite ligaments of this articulation. 



(i) Anterior sacro-iliac, from pelvic brim to greater sacro-sciatic foramen ; 

 (2) posterior sacro-iliac, from back of sacrum to iliac crest ; (3) superior sacro- 

 iliac, from sacral base to iliac fossa; (4) inferior sacro-iliac, from sacrum to \< 

 terior iliac spine ; (5) interosseous ligament is between the two spines. 



The function of the sacro-iliac ligaments is to bind the sacrum to the ilium. 



Posterior or great sacro- 

 sciatic ligament 



Anterior or email sacro- 

 solatlo ligament 



Falciform process of the 

 great ligament 



. Tendon of biceps muscle, continuous with 

 the great sacro-aciatic ligament 



FIG. 328. SACRO-SCIATIC LIGAMENTS. (Posterior view.) 



They are purely of periosteal derivation. The plate of cartilage between the 

 bones may become ossified, just as the ligaments of the vertebral column some- 

 times do. Occasionally, a distinct synovial cavity is found in the center of this 

 cartilage. 



Sacro-ischiatic Ligaments : 



Hmv many ligaments unite the sacrum, and iscliium ? (Fig. 328.) 



Two ; the common name for these is sacro-sciatic, which is a contraction of 

 the true word for purposes of euphony. The common names are : (i) Greater 

 or posterior sacro-sciatic ligament; (2) lesser or anterior sacro-sciatic ligament. 



Locate the greater ligament. 



The greater or posterior sacro-sciatic ligament is attached above to the mar- 

 gin of the sacrum and coccyx and to the posterior inferior iliac spine ; below to 

 the inner margin of the tuber of the ischium and ascending ramus of the ischium 

 for about two inches. 

 3 



