398 
ANATOMY OF THE HORSE. 
with the dilatator naris lateralis; internally, with the nasalis lon- 
gus labii superiors, pes anserinus, and the superior labial artery. 
Direction. —Rather oblique, from behind forwards inclining 
downwards. 
Structure. —Posteriorly, a broad and extended aponeurosis; 
anteriorly, fleshy. 
Use. —To assist in the retraction of the upper lip and angle of 
the mouth, and in the dilatation of both the true and false nostrils. 
Remark. —Stubbs describes the aponeurotic expansion of this 
muscle under the name of “ epicranius.” 
dilatator naris latlralis. — Super-maxillo-nasalis magnus. 
Situation. —Upon the side of the face. 
Figure. —Flat, pyramidal, base presented forwards. 
Attachments. —Posteriorly, to the fore end of the zygoma, and 
to the superior maxilla for a short space in front of it; anteriorly, 
it spreads upon the side of the nostril and the supero-lateral parts 
of the upper lip. 
Relations. —Externally, with the skin and the inferior division 
of the preceding muscle ; internally, with the superior division of 
the same muscle, the caninus, the superior maxillary bone, and 
the superior labial bloodvessels and nerves. 
Direction. —HorizonUT divergent as it proceeds forwards. 
Structure. —A slender tendon attaches it to the bone, below 
which it is fleshy. 
Use. —To dilate the nostril and retract the upper lip. 
nasalis lon g us labii superioris. — Super-maxillo-lahialis. 
Situation. —Upon the upper part of the side of the face. 
Fi gure. —Elongated, pyramidal, base turned backwards : ex¬ 
ternal surface, convex; internal, flat. 
Attachments. —Posteriorly, to a slight bony depression at the 
junction of the superior maxillary and malar bones, a short dis¬ 
tance from the lower margin of the orbit; anteriorly, along the 
middle of the anterior part of the upper lip. 
Relations. — Externally, with the skin and the levator labii su¬ 
perioris alasque nasi, and the angular vein; internally, with the 
superior maxilla, pes anserinus, and false nostrils: the united 
tendon crosses, in front, the dilatator naris anterior, and at the 
border of the lip enters the substance of the labial gland. 
Di rection. —Horizontal, the fleshy fibres gradually converging 
from their origin to their termination in the tendon. 
Structure. —It has a few tendinous fibres at its origin; other- 
