304 
ANATOMY OF THE HORSE. 
quarters remain stationary and fixed points, it will produce that 
appearance, by flexing the spine, called “ roach-back,” or 
u sticking up the back/ 7 
i li a c u s.— Ileo-trocliantineus. 
0 
Situation. —Occupying the iliac fossa, and thence extended 
along the internal part of the haunch. 
Form. —Thick; triangular; base turned forwards. 
Attachment. —Anteriorly and superiorly, to that part of the 
crista of the ileum which has no bearing upon the sacrum; and 
to the anterior spinous process, venter, and inferior edge of the 
bone: posteriorly and inferiorly, to the small internal trochanter, 
along with the psoas magnus. 
Relations. —Inferiorly, with the crural arch; superiorly, with 
the psoas magnus and sartorius; on the outer side, with the iliac 
fossa, tensor vaginae, rectus, and ileo-femoral articulation ; on the 
inner, with the iliac faschia and peritoneum. The anterior crural 
nerve and profunda artery and vein cross its lower termination. 
Structure. —Enveloped entirely internally, and in part exter¬ 
nally, by a faschia derived from the crural arch. It is altogether 
fleshy excepting its lower part, which joins in inseparable union 
with the tendon of the psoas magnus. 
Action. —To flex or advance the haunch. 
psoas parvus. — Sub-lumbo-pubialis. 
Situation. —Along the inner side of the preceding muscle. 
Figure. —Elongated, slender, fusiform. 
Attachment. —Anteriorly, to the heads of the 16th, 17th, and 
18th ribs; to the bodies of the three posterior dorsal, and to those 
of all the lumbar vertebra ; posteriorly, to the brim of the pelvis, 
midway between the anterior spine and the symphysis pubis. 
Relations. —Anteriorly, with the diaphragm and the renal 
vessels; on the inner side, with the crus of the diaphragm, ante¬ 
rior aorta, and vena cava, and the iliac vessels; on the outer side, 
with the iliacus. 
F)irection. —Longitudinal. 
Structure. —Anterior attachments, fleshy; with tendinous 
chords intermixed : posterior half, a long flattened tendon, which 
arises out of the middle of the fleshy parts and broadens in its 
passage backwards. 
Action. —To draw the pelvis forwards. When one acts by 
itself, the same pail will be inclined to one side. Or, the pelvis 
being made a fixture, it will have effect in arching or flexing the 
spine. 
[To be continued.] 
