Owing to the presence of the fibrous pad to which the whiskers are
attached, the facial muscles between the eye and the mouth differ in the
cat in some respects from those of related animals. This fibrous pad
interrupts the muscles, frequently breaking muscles which are elsewhere
single into two.
=M. zygomaticus minor=, or malaris (Fig. 64, _e_).--This muscle is not
always present; when it exists it forms a very thin flat band of fibres
passing from the ventral side of the eye toward the angle of the mouth.
_Origin_ among the fibres of the orbicularis oculi (_s_) in the lower
eyelid. The fibres pass ventrad; the insertion varies. In some specimens
the insertion is among the fibres of the orbicularis oris (_i_), at the
angle of the mouth, beneath the zygomaticus (_d_). In other cases this
muscle is said to be inserted into the pad on which the whiskers rest.
_Relations._--Outer surface with the integument and near its insertion
with the zygomaticus major (_d_). Inner surface with the malar bone and
the masseter muscle.
_Action._--Pulls the angle of the mouth (or the whiskers) dorsad.
=M. orbicularis oris= (Fig. 64, _i_).--This forms a very thin layer of
subcutaneous concentric fibres which surround the mouth, that of the
upper lip being thicker than that of the lower lip. The part of the
muscle in the lower lip has its fibres intermingled with those of the
platysma (_a′_). In the median line the fibres of the upper lip are
interrupted by a raphe, and caudad of this are intermingled with those
of the caninus.
=M. quadratus labii superioris= (Fig. 63, _p_ and _q_; Fig. 64, _f_ and
_g_).--This is a complex of muscle-fibres attached chiefly to the
fibrous pad on which the whiskers rest. In it two parts can be
distinguished more or less completely.
(1) =M. levator labii superioris alæque nasi= (Fig. 63, _p_; Fig. 64,
_g_) on the sides of the nose. This arises (_a_) as a continuation of
the frontal portion of the epicranius, and (_b_) in a small bundle (Fig.
63, _p_) from near the dorsal end of the frontal process of the
maxillary bone, in common with the next. The two slips thus formed
unite craniad and are inserted partly into the integument on the outer
side of the wing of the nose, partly into the skin of the upper lip,
lateroventrad of the nose, and partly into the pad on which the whiskers
are located, in connection with the next.
(2) The =angular= head (=caput angulare=), or =levator labii superioris
proprius= (Fig. 63, _q_; Fig. 64, _f_) is much larger than the last. It
takes origin from a small tubercle at the cranial border of the orbit,
close to the origin of the orbicularis oculi. The fibres diverge from
their origin to their insertion among the whiskers and in the fibrous
pad on which the whiskers rest.
_Action._--Erects the whiskers and raises the upper lip.
=M. caninus= or =levator anguli oris= (Fig. 64, _f′_).
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