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166 ANATOMY.

local injuries reduces the size and tonicity of muscles, and this atrophied
condition often remains persistent. Modern surgery, to avoid this and
other pathological sequences, attempts the adjustment and fixation of
the ends of fractured bones with as little loss of muscular exercise as
possible.
The Number of Muscles.—The whole number of muscles belong-
ing to the voluntary system is about 229 : those of the head, 52 ;
of the neck, 24, exclusive of those belonging to the vertebral column.
The muscles of the head are divided into four groups—those of the
face, auricle, orbit, and of mastication.
The facial muscles (Fig. 88) are subdivided into three sets, named,
according to their location, the fronto-palpebi'al, the nasal, and the oral.
The fronto-palpebral muscles are the occipito-frontalis, the pyra-
raidalis nasi, the orbicularis palpebrarum, and the corrugator supercilii.
The nasal muscles are the compressor nasi, the depressor ake nasi, the
dilator naris anterior, and the compressor narium minor.
The oral muscles are the orbicularis oris, the levator labii superioris
aheque nasi, the levator labii superioris proprius, the depressor labii
superioris, the zygomaticus minor, the zygomaticus major, the levator
anguli oris, the risorius, the de])ressor anguli oris, tlie depressor labii
inferioris, the levator labii inferioris, and the buccinator.
The muscles of the auricle consist of the attolens aurem, the attrahens
aurem, and the retrahens aurem.
The muscles of the orbit are the levator palpebrse, the rectus supe-
rioris, the rectus inferioris, the rectus internus, the rectus externus, the
obliquus superioris, and the obliquus inferioris.
The muscles of mastication are the masseter, the temporalis, the
pterygoideus externus, and the pterygoideus internus.
The muscles of the neck are the platysma myoides, sterno-cleido-
mastoideus, the depressors of the hyoid bone, the muscles of the supra-
hyoid space, those of the ])harynx and soft palate, the deep lateral, and
the prevertebrals.

The Facial Muscles.

The facial differ markedly from all other voluntary muscles of the
body. In the first place, some of them have no bony origin ; none
have bony insertions. That is to say, some of the facial muscles have
but one extremity attached tc; bone, the other being inserted into mus-
cles; while, again, several liave no osseous attachment whatever. Their
fibres are more delicate, and, having no investing sheath of perimysium,
merge one into the other.
The voluntary muscles of the face are not as wholly under the power
of the will as are the voluntary muscles of the limbs, and are often
aifected by mental impressions.
The Occipito-frontalis is in reality two muscles divided by an
aponeurosis. These are called the Occipitalis and the Frontalis.
The Occipitalis Muscle is thin and flat, arises from the outer two-
thirds of the superior semicircular line of the occipital bone and the
mastoid portion of the temporal bone above the attachment of the