: ////. 



Angles. Tho external, also named tin". ootyloidcmgbjiB the thickest of tin- 

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

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

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

 with the antero-interual 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. Tho superior is smooth and nearly plane, and forms part of tlie 

 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 VIKW. 



1, Crest of the ilium ; 2, Angle of the croup ; .'{, Shaft of the ilium ; 4, 

 cavity, or ncetnbulum ; 6, Ischial spine. 



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

 posteriorly. The posterior, straight and directed obliquely forwards and 

 inwards, forms, with the analogous border of the opposite bone, a large; 

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

 depressed lip (the spine), arising from the side of the inferior face. Tho ex- 

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

 is joined to the ischium of the other side to constitute a portion of the pelvic 

 symphysis. 



Angles. Tho antero-external or cotyloidean is the most voluminous of the 

 four, and affords for study : 1, An excavated diarthrodial facet, making part 

 of the cotyloid cavity; 2, The posterior extremity of the supor-cotyloid. an 

 crest, limited by a small transverse fissure which separates it from tin.- 

 external border of the bone. The antero-internal angle is consolidated \\ith 

 the posterior angle of the pubis. Tho poster o- external angle forms the 

 ischiatic tulterosity. This is a largo prismatic process which looks upwards, 

 and is prolonged by a salient ridge, elongated from before to behind, with 

 its sharp border turned outwards and downwards. Tho postero-inlcrnal <nnjl<' 



