94 THE BONES. 



Angles. — The external, also named the cotyloid angle, is the thickest of the 

 liiree. To it chiefly belongs the rugged depressed surface that constitutes 

 the bottom of the cotyloid cavity. The internal unites with the analogous 

 angle of the opposite pubis. The posterior is consolidated at an early period 

 with the antero-intemal angle of the ischium, to inclose, inwardly, the oval 

 foramen. 



Ischium. — This is the mean, in volume, of the three pieces of the coxa. 

 Situated behind the pubis and ilium, it is flattened above and below, and of 

 a quadrilateral form. It offers for study : two faces, four borders, and four 

 angles. 



Faces. — The superior is smooth and nearly plane, and forms part of the 

 floor of the pelvic cavity. It has a small nutritious foramen directed out- 

 wards. The inferior presents some rugosities clustered particularly about 

 the symphysis. 



Fig. 60. 



PELVIS; LATERAL VIEW. 



1, Crest of the ilium ; 2 Angle of the croup ; 3, Shaft of the ilium ; 4, Cotyloid 



cavity, or acetabulum ; 6, Ischial spine. 



Borders.— The anterior, thick and concave, circumscribes the oval foramen 

 posteriorly. The posterior, straight and directed obliquely forwards and 

 inwards, forms, w;ith the analogous border of the opposite bone a laree 

 notch named the ischiatic arch. It exhibits, throughout its extent, a rugged 

 depressed lip (the spine), arising from the side of the inferior face The ea;- 

 ternal, thick and concave, constitutes the lesser ischiatic notch The internal 

 18 joined to the ischium of the other side to constitute a portion of the nelvic 

 symphysis. i'ci.j»y 



Angles.— The antero-external or eoiyloidean is the most voluminous of the 

 four and affords forstudy : 1, An excavated diarthrodial facet mS part 

 cres' iSefbTI^' ^'/he posterior extremity of the super-c^S^oid'ean 

 crest, limited by a small transverse fissure which separates it from the 

 external border of the bone. The antero-intemal angle is consolidated with 

 tchi!tTfT T^'^t- '^' ^f''- ^^'^ Po^terolternal angle ^jTe 



Za t ^"^r"* •^•i, ^^'' 1? ^ '^-T P"''°''*'*' P''"'^^^ ^^^0^ looks upwards! 

 and IS prolonged by a salient ridge, elongated from before to beHnd with 

 Its sharp border turned outwards and dowLards. The poLro-^iS an^e 



