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172 ANATOMY.

of the upper lip. It is thin and quadrilateral in outline, arising imme-
diately below the orbital cavity above the intraorbital foramen. Its
origin is chiefly confined to the superior maxilla, but a few of its fibres
extend from the malar bone. It passes downward and inward to be
inserted into the orbicularis oris and the integument of the superior lip.
It is situated on the same general plane as tlie levator labii snperioris
alteque nasi, and is connected with it throughout its lower third.
Relation)^.—By its superficial surface with the orbicularis palpebrarum
and the integument ; by its inner surface with the infraorbital nerve
and its accompanying vessels as they emerge from the infraorbital fora-
men, a portion of the levator anguli oris, and the origin of the com-
pressor nasi muscle.
The Depressor Labii Siq^erioris is a small muscle arising from the
lower portion of the incisive fossa of the superior maxilla and ihe
alveolar process immediately below the fossa. Its fibres pass upward
to the lower border of the nostrils and the partition of the nose. A
portion of the fibres of this muscle are attached to the integument cov-
ering the wing of the nose ; the balance pass downward and are inoscu-
lated with the fibres of the muscles of the upper lip. It, with its fellow
and the mucous membrane, forms the frifiuuni of the upper lip, and when
the alveolar process is absorbed after the loss of the teeth, it is often found
attached on the lower margin of the gum.
Re/ations.—Within the vestibule of the mouth it is covered by mucous
membrane ; above that portion it is covered with the muscles of the
upper lip ; its deep surface rests upon the bone, and the median border
joins with its fellow of the opposite side.
The Zyc/omaticus Minor is an extremely slender muscle arising from
the anterior inferior jx»rtion of the malar bone, just behind the malo-
maxillary suture. It passes downward and forward, its fibres becom-
ing lost in those of the special elevator muscle of the upper lip near the
angle of the mouth.
Rekdions.—By its superficial surface with the orbicularis palpebrarum
and the integument ; by its deep surface with the levator anguli oris.
The Zygomaticm Major is situated just external to the smaller muscle
of the same name. It arises from the malar bone in close proximity to
the zygomatic suture, and passes obliquely downward to the angle of the
mouth, where it is attached to the integument and becomes blended with
the fibres of the orbicularis oris and depressor anguli oris muscles.
Relations.— By its superficial surface with the subcutaneous adipose
tissue ; by its deep surface with the malar bone and the masseter and
buccinator muscles.
Variations.—The zygoraaticus minor is oflen absent, and occasionally
its fibres are lost in the integument before reaching the muscle of the lip.
At times also it arises in part or entirely from the orl)icularis palpebra-
rum muscle, and is blended with the zygomaticus major and the levator
labii su]>erioris. Occasionally it is separated into two muscles. The
zygomaticus major is also occasionally wanting, or it may be double,
and arises at times from the masseteric fascia.
The Levator Anr/ii/i Oris (canine muscle) arises from the canine fossa
immediately below the infraorbital foramen. It passes downward and