-ANATOMY OT THE HORSE. 
113 
or appendices to them. The border itself is called the cristei 
ilei. It affords attachment to the longissirnus dorsi, obliqui 
abdominis, externus et internus, and transversalis abdominis.. 
Posterior Border —Having its anterior third thick and scab¬ 
rous, where it is united through the intervention of fibrous car¬ 
tilage with its fellow, forming the symphysis pubis ; posteriorly 
to this, it grows thin, which part has also a ligamentous connec¬ 
tion wdth the opposite bone, and afterwards recedes from its 
fellow, terminating outwardly in a thick, oblong, waving, rough¬ 
ened prominence, called the tuberosity of the ischium, to which 
are attached the adductor magnus, biceps femoris, and abduc¬ 
tor tibialis, and also the sacro-sciatic ligaments. 
The Superior Border —Extending from the posterior iliac spine 
to the ischiatic tuberosity, is waving in its course, forming an ir¬ 
regular semi-circle, and presents along its anterior two-thirds a 
sharp edge, which opposite to the acetabulum is roughened by 
the implantation of the sacro-sciatic ligaments ; after this if is 
rounded by the play over it of the obturator internus and ge- 
melli, and at length ends insensibly in the tuberosity.—There is 
a lesser superior border'which runs from the tuberosity to the 
acetabulum: the posterior half is prominent, very sharp, and 
irregular, forming the ischiatic spine. 
The Inferior Border —Describes a sigmoid flexure : it extends 
from the anterior iliac spine to the symphysis pubis. Its ante¬ 
rior third is sharp; about its middle is a medullary hole run¬ 
ning backward ; here it gives rise to two borders : one obtuse 
and smooth, ending at the edge of the acetabulum; the other, 
more prominent and sharp, is the linea ilio-pectinea, or brim or 
boundary of the cavity of the pelvis, running onward to the 
symphysis. Upon its anterior part is a rough place, the ilio- 
pectineal eminence, marking the insertion of the psoas parvus ; 
posteriorly are two rough eminences, with a groove between 
them wherein run the united tendons of the psoas magnus and 
iliacus: to the outer one, the pubic spine, is fixed the external 
chord of the abdominal ring. 
Connection,, Anteriorly and inferiorly with the sacrum; pos¬ 
teriorly and inferiorly and in the middle with each other; out¬ 
wardly wdth the femoral bones. 
Development, In the foetus this bone is separable into three 
distinctly formed pieces :—the ileum, the largest division, the 
triangular plate in front; the ischium, the part projecting back¬ 
wards ; and the pubes, the inferior and middle portion. They 
all contribute to the formation of the acetabulum ; the ischium 
and pubes alone form the obturator foramen. These parts 
speedily complete their bony union after birth ; and the ischium 
and pubes the soonest. 
VoL. I.—No. 4. 
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