64 
ANATOMY OF THE HORSE. 
Attachments .—AVithin the pelvis, to the tranverse processes of 
the sacrum, and infero-internal part of the ileum: without the 
pelvis, to the hollow behind the trochanter major. 
Relations. —Superiorly and externally, with the,pelvis; in- 
feriorly and internally, with the peritoneum: along’ its inferior 
border run the obturator bloodvessels and nerves. 
Structure. —Composed of a fleshy belly, having* its superior 
border tendinous; which border, after the muscle has passed 
through the sciatic notch, gives origin to a slender tendon 
that insinuates itself between the gemini to gain the tro¬ 
chanter. 
Action. —To assist in the extension of the haunch. 
obturator externus. — Subpubio-tro chant erius Ext emus. 
Situation. —Deep-seated, in the supero-internal part of the 
thigh. 
Form .—Quadrilateral, and putting on the appearance of a 
double muscle. 
Attachments. —Internally, to the external border of the obtu¬ 
rator foramen, and to the external surface of the obturator liga¬ 
ment: externally, to the cavity behind the trochanter major, 
and to the upper portion of the ridge extending from the larger 
to the lesser trochanter. 
Relations. —Posteriorly, with the biceps abductor; superiorly, 
with the gemini and obturator internus; internally, with the 
adductor magnus. 
Direction. —Outward. 
Structure. —Attachments both tendinous and fleshy ; surfaces 
striped with apeneurotic tendon. 
Action. —To assist in the extension of the haunch ; and at the 
same time to rotate it outwards. 
obturator internus. — Subpubio-trochanterius Internus. 
Situation.— Upon the lower side of the pelvic cavity. 
Form.— Circular border, having radiating fibres converging 
towards one common centre. 
Attachments. —Internally, to the internal border of the ob¬ 
turator foramen, and to the inner surface of the obturator liga¬ 
ment : externally, to the root of the trochanter major. 
Relations. —Superiorly, with the peritoneum; inferiorJy, with 
the obturator ligament. 
Structure. —From the foramen the fleshy fibres converge 
and form a belly which passes between the tuberosity and 
