Page 35 - My FlipBook

33
brane ; which arises by the semicircular ridge on the side of
the cranium, and is inserted into the upper margin of the
zygoma.
The temporal muscle arises from the inner face of this
fascia; from the whole length of the semicircular ridge on
the side of the os-frontis and parietale; and from the surface
of the cranium between this ridge and the zygoma, includ-
ing a part of the frontal bone of the parietal, and of the
squamous portion of the temporal. This muscle also re-
ceives accession of fleshy fibres from the internal face of the
zygoma.
From this extensive origin the fibres converge towards the
zygoma, and passing beneath it, are inserted tendinous into
the coronoid process of the lower jaw, so as to surround it
on every side ; some of the tendinous fibres go down in front
almost to the last dens molaris. It pulls the lower jaw direct-
ly upwards.
Pterygoideus Externus.
The external pterygoid muscle, so called from its position,
arises fleshy from the outer side of the external pterygoid
process of the sphenoid bone ; from the tuber of the upper
maxilla ; and from the under surface of the temporal process
of the sphenoid bone.
It passes outwards and backwards horizontally, and is in-
serted into the inner side of the neck of the inferior maxilla,
and into the capsular ligament of the articulation.
When the muscles of the opposite sides act together, they
draw the lower jaw forwards, but if alternately, they give it
a grinding motion.

Pterygoideus Internus.
The internal pterygoid muscle arises by tendinous and
fleshy fibres from the internal plate of the pterygoid process
5