The =auricular muscles= may be subdivided into two sets, viz., (_a_)
extrinsic muscles, which arise on the head and adjacent part of the
neck, and move the external ear as a whole, and (_b_) intrinsic muscles,
which are confined to the auricula. In this connection the scutiform
cartilage may be regarded as a sesamoid cartilage intercalated in the
course of some of the muscles.
The =extrinsic muscles= are as follows:
1. The =scutularis= is a thin muscular sheet situated subcutaneously
over the temporalis muscle. Its fibers arise from the zygomatic arch and
the frontal and sagittal crests, and converge to the scutiform
cartilage. It consists of three parts.
(_a_) The =fronto-scutularis= comprises temporal and frontal parts,
which arise from the zygomatic arch and the frontal crest, and are
inserted into the outer and anterior borders of the scutiform cartilage
respectively.
(_b_) The =interscutularis= arises from the sagittal crest, over which
it is in part continuous with the muscle of the opposite side. Its
fibers converge to the inner border of the scutiform cartilage.
(_c_) The =cervico-scutularis= is not well defined from the preceding
muscle. It arises from the occipital crest and is inserted into the
inner border of the scutiform cartilage.
2. The =anterior auricular muscles= (Mm. auriculares nasales) are four
in number.
(_a_) The =zygomatico-auricularis= arises from the zygomatic arch and
the parotid fascia, and is inserted into the outer face of the base of
the conchal cartilage under cover of the parotido-auricularis.
(_b_) The =scutulo-auricularis superficialis inferior= arises on the
outer part of the superficial face of the scutiform cartilage and ends
on the base of the conchal cartilage with the preceding muscle.
(_c_) The =scutulo-auricularis superficialis medius= arises from the
posterior part of the deep surface of the scutiform cartilage and is
inserted into the dorsum of the conchal cartilage, close to the lower
part of its anterior border and above and behind the preceding muscle.
It receives a slip from the cervico-scutularis.
(_d_) The =scutulo-auricularis superficialis superior= is a thin slip
which is detached from the interscutularis over the inner border of the
scutiform cartilage. It ends on the anterior aspect of the lower part of
the dorsum of the conchal cartilage.
3. The =superior auricular muscles= (Mm. auriculares dorsales) are two
in number.
(_a_) The =scutulo-auricularis superficialis accessorius= is a narrow
band which is largely covered by the preceding muscle. It arises from
the posterior prolongation and the adjacent part of the superficial face
of the scutiform cartilage, and is inserted into the convex surface of
the conchal cartilage internal to the preceding muscle, the two crossing
each other at an acute angle.
(_b_) The =parieto-auricularis= is flat and triangular; it arises from
the sagittal crest under cover of the cervico-scutularis, runs outward
and a little backward, and is inserted by a flat tendon into the lower
part of the convex surface of the concha under cover of the
cervico-auricularis superficialis.
4. The =posterior auricular muscles= (Mm. auriculares caudales) are
three in number.
[Illustration: