Action.—Raises the upper lip.
M. myrtiformis (probably corresponds to a part of the human M. nasalis) ([Fig. 64], h).—A thin sheet of muscle-fibres lying craniad of the levator labii superioris alæque nasi and passing from the whiskers to the nose and upper lip. It is distinguishable from the alæque nasi by the direction of the fibres.
Origin from the pad upon which the whiskers rest. The fibres diverge and have their
Insertion upon the wing of the nose and into the skin of the upper lip near the median line.
Action.—Dilator of the nares and elevator of the upper lip.
M. “moustachier” (Str.-D.) (probably corresponds to one of the Mm. incisivi).—It lies on the upper lip near the median line.
Origin from the outer surface of the premaxilla near the suture along the ventral border of the narial opening. The fibres diverge and pass caudad into the upper lip within the superficial fibres of the orbicularis oris.
Insertion.—The skin of the upper lip just craniad of the whiskers. Some of the fibres pass into the pad on which the whiskers rest.
Action.—It carries the lip craniad.
M. quadratus labii inferioris.—A thin flat band extending almost the length of the lower lip.