Hooper, Robert [Editor]: The Anatomist's Vade-Mecum: Containing The Anatomy, Physiology, Morbid Appearances, &c. Of The Human Body ; The Art of making Anatomical Preparations, &c. To which are added Anatomical, Physiological, Medical, And Surgical Examinations For Students (London, 1811)

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MUSCLES OF THE INTERNAL EAR.

Laxator tympani.—Externus malleu-—This muscle arises
from the spinous process of tlie sphenoid bone, and proceeds
into the cavity of the tympanum, to be inserted into the
long process of the malleus. Its use is to draw the malleus
obliquely forwards towards its origin.

Tensor tympani.—Internum mallei.—Arises from the
cartilaginous extremity of the Eustachian tube, within the
tympanum, and is inserted into the manubrium of the malleus.
By contracting, this muscle pulls the malleus and membrana
tympani inwards.

Stapedius......This delicate muscle arises from a little ca-
vern in the tympanum, near the cells of the mastoid process,
and passes in a bony furrow to be inserted iuto the posterior
part of the head of the stapes, which, by contracting, it
draws upwards.

MUSCLES OF THE LOWER JAW.

Temporalis.—Temporo-maxillaris.-—This great muscle of
the lower jaw arises from a semicircular ridge in the lower
part of the parietal bone, and from the sphamoid, tem-
poral, and frontal bones in the hoHow behind the eye,
where they meet to form the squamous suture ; and from the
aponeurosis which covers it. Its fibres are bundled together,
and pass in a narrow compass under the zygoma, to be in-
serted all around the coronoid process of the lower jaw.
Its use is to pull the lower jaw upwards, which it does very
powerfully.

Spasm of this muscle constitutes trismus, or locked-jaw.