_a_, Levator labii superioris proprius; _b_, levator nasolabialis; _c_, mastoido-humeralis; _d_, sterno-cephalicus; _d′_, tendon of _d_; _e_, omo-hyoideus; _f_, dilatator naris lateralis; _g_, zygomaticus; _h_, buccinator; _i_, depressor labii inferioris; _k_, orbicularis oris; _l_, dilatator naris superior; _m_, masseter; _n_, parotido-auricularis; _o_, zygomatico-auricularis; _p_, interscutularis; _p′_, fronto-scutularis, pars temporalis; _q_, cervico-auricularis profundus major; _r_, cervico-auricularis superficialis; _s_, obliquus capitis anterior; _t_, splenius; v, stylo-maxillaris; _y_, mastoid tendon of mastoido-humeralis; _2_, posterior, _3_, anterior, border of external ear; _8_, scutiform cartilage; _9_, zygomatic arch; _10_, depression behind supraorbital process; _18_, temporo-mandibular articulation; _27_, facial crest; _30′_, angle of jaw; _37_, external maxillary vein; _38_, jugular vein; 39, facial vein; _40_, parotid duct; _41_, transverse facial vein; _42_, masseteric vein; _43_, facial nerve; _44_, parotid gland; _45_, chin; _x_, wing of atlas. (After Ellenberger-Baum, Anat. für Künstler.) ] 2. =Levator nasolabialis= (Levator labii superioris alæque nasi).—This thin muscle lies directly under the skin, and chiefly on the lateral surface of the nasal region. _Origin._—The frontal and nasal bones. _Insertion._—(1) The upper lip and the outer wing of the nostril; (2) the commissure of the lips. _Action._—(1) To elevate the upper lip and the commissure; (2) to dilate the nostril. _Structure._—The muscle arises by a thin aponeurosis. The belly is also thin, and divides into two branches, between which the lateral dilator of the nostril passes. The dorsal branch reaches the nostril and upper lip, blending with the lateral dilator; the ventral one is much smaller, and blends at the labial commissure with the orbicularis and buccinator. _Relations._—Superficially, the skin, fascia, and lateral dilator (in part); deeply, the levator labii superioris proprius, lateral dilator (in part), buccinator, branches of the facial vessels and nerve, and the infraorbital artery and nerve. _Blood-supply._—Facial and palato-labial arteries. _Nerve-supply._—Facial nerve. [Illustration: FIG. 173.—MUSCLES OF HEAD OF HORSE, DORSAL VIEW. THE PANNICULUS IS REMOVED.