44 THE SURGICAL ANATOMY OF THE HORSE 



gluteal and sacral surfaces we have the ischiatic edge. This edge 

 is thin and sharp, and for the greater part of its extent it presents a 

 greater degree of curvature than the cotyloid edge, the concavity 

 being directed upwards and backwards. Towards its middle third this 

 edge forms the anterior boundary of the greater sacro-sciatic foramen. 

 Above the foramen it gives attachment to the inferior ilio-sacral 

 ligament. A small but well-defined tubercle, which is placed towards the 

 inner aspect of the bone indicates the inferior limit of the ligamentous 

 attachment. The inferior portion of this edge is raised into a prominent 

 ridge which is placed above the cotyloid cavity. This ridge forms part 

 of the superior ischiatic spine. On its outer aspect it is roughened and 

 affords attachment to the great sacro-sciatic ligament. 



The remaining edge separates the iliac and pelvic surfaces. This 

 is the pubic edge, and is so named because it conducts inferiorly to the 

 pubic bone. Superiorly it will be observed that the iliac and pelvic 

 surfaces are blended with one another for the upper portion of the pubic 

 edge is obliterated. The ilio-pectineal eminence will be found in the 

 inferior third of this edge. To the eminence the tendon of the psoas 

 parvus muscle is attached. The pubic edge is also termed the ilio- 

 pectineal line. 



The ilium possesses three angles which, according to their position, 

 may be termed the antero-internal, antero-external, and inferior. The 

 antero-external angle, or the angle of the haunch, forms the most 

 prominent landmark in the living subject in this region, and to it 

 attention has already been drawn in our superficial examination. It is 

 now seen to be very massive and to be made up of two pairs of 

 roughened tuberosities, one pair being placed above and the other 

 below. Several muscles are attached to this angle, including the oblique 

 muscles of the abdomen, the tensor vaginas femoris, &c. The antero- 

 internal angle, or angle of the croup, is that portion of the ilium 

 which is placed above and rests upon the sacrum. The angle itself is 

 acute and is formed between the crest and the ischiatic border. The 



