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AREOLAE TISSUE, TENDONS, AND MUSCLES. 171
aponeurosis, uniting- with the corresponding muscle of the op})osite side
and with the pyramidaHs nasi.
The Depressor Alee Nasi are short radiated muscles arising from the
incisive fossse of the superior maxillte, the fibres passing upward to be
inserted into the integument of the nasal septum and to the alee of the
nose.
Besides those just described, there are several other muscles, with
irregular and indistinct fasciculi, which assist in enlarging the opening
of the nose. Among these are the compressor narium minor and the
dilatores naris anterior and posterior.
The Oral Group (Fig. 89) consists of the orbicularis and those
muscles having their insertion into it.
The Orbicularis Oris is a thin layer of muscular fibres, forming the
sphincter of the mouth. It is elliptical in form, its fibres being con-
tinued from one lip to the other around the angles of the oral opening.
It is divided into two portions, labial and facial, the labial or marginal
circle or rim forming the red portion of the lij). Tlie iacial or external
portion blends with the muscles which converge toward the mouth,
its fibres being inserted into them, and acting antagonistically to them.
The portion of this muscle corresponding to the upper lip is composed
of four slips of muscular fibres, two situated on each side of the cen-
tral portion. The outer slips are thin and weak, ])ass downward, and
are attached to the superior maxilla in the incisor fossa below the ori-
gin of the depressor alse nasi. The inner two slips, thicker and stronger,
pass upward, and are inserted into the septum of the nose. At the
median line the space between these slips corresponds to the perpendic-
ular groove on the lip immediately below the nose. The two fasciculi
of the loAAcr lip arise in the incisor fossa of the inferior maxilla exter-
nal to the levator labii inferioris. They pass upward and outAvard
toward the angles of the mouth, their fibres interlacing with the other
muscles of the lip.
Relations.—By the inner margin of the superficial surface it is closely
connected with the integument, whilst superimposed between the outer
portion and the integument is a layer of fatty tissue ; by its deep surface
with the mucous membrane, labial glands, and coronary arch of vessels
of each lip. Its internal circumference is immediately beneath the integu-
ment, and forms the free margins of the lips, whilst the outer circum-
ference is blended with the several muscles that converge from various
portions of the face to this point or muscle.
The Levator Labii Superioris Alceque Nasi is a thin triangular muscle
situated along the side of the nose, extending from the inner angle of
the orbital cavity to the ujjper lip. It arises by a pointed extension
from the upper and outer part of the nasal ])rocess of the superior
maxilla, passes downward and outward, and divides into two portions.
The smaller of these is inserted into the ala of the nose, the other being
prolonged downward and blending with the orbicularis oris and the
special elevator muscle of the upper lip.
Belations.—By its superficial surface superiorly with the oi'bicularis
palpebrarum, and below with the integument.
The Levator Labii Superioris Propi'ius is the special elevator muscle