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198 ANAT03IY.

tendency to close the orifice of the tube by elevating the lower border.
The action of the levator palati can readily be studied in the living sub-
ject by the rhinal mirror. By such aid the course of the muscle, even
when at rest, can be seen corresponding to an oblique fold of mucous
membrane, which may receive the name of the salpingo-palatal fold.
The levator palati receives much attention in the improved operation
of staphylorrhaphy. Fergusson, having noticed the influence of this
muscle in widening the cleft in the soft palate, essays its division before
uniting the freshened edges. This procedure is now an established
antecedent to the operation.
" The actions of the levator palati and tensor palati muscles have been
the subject of controversy. Valsalva as long ago as 1742 described
both the above muscles as dilators of the tube. Toynbee^ in 1853
revived Valsalva's account, and later Riidinger and other German
writers have accepted this as the true action. Respecting the tensor
palati, Henle ^ is inclined to adopt the view that the muscle closes the
orifice.; while, as seen in another part of the same volume (p. 117), he
doubts the ability of the muscle to close the tube. His views upon the
function of the levator palati agree with those expressed in the text.
" The author has long taught that the contraction of the levator palati
narrows the plraryngoal orifice of the tube. This action can be readily
seen in the living subject by the aid of reflected light. Cleland^ studied
the action of the same muscles in a man who had lost the soft palate by
ulceration. He doubts the efficacy of the tensor palati in dilating the
tube, while he assigns to the levator palati its proper function, in assist-
ing to narrow the orifice. That the Eustachian tube (q. v.) is always
patulous in health, and that while certain muscles tend to narrow its
lumen none can obliterate it, seem to be fair deductions from its nature."*
The Azi/gos Uvuke is not a single muscle, as its name implies, but
consists of a pair of narrow fasciculi, arising, one on each side, from the
posterior palatine spine of the palate bone and the aponeurosis of the
soft palate, the fibres passing backward to be inserted into the uvula.
Kerves.—The muscle is controlled by the facial nerve.
Action.—To contract the uvula.

Mucous Membrane and its Glands.
Mucous membrane forms the lining of all cavities and canals having
an external opening, such as the respiratory tracts, the passages trans-
mitting fjod in its various forms, and all outlets for excretive and secre-
tive fluids. The surface of the membrane is soft and yielding, and is
covered by a thick glistening, tenacious, transparent fluid called mucus,
which is secreted by numerous small glands hereafter to be described.
The mucus protects the membrane beneath from any deleterious matter
contained in foods, either in a solid state or in the form of solution.
The nnicous membrane of tlie body can l)e divided int(j two great
systems— the genito-urinary and the gastro-pneumonic— each being
complete and continuous in itself.
^ Trans. Phil. Soc. LonrK, 1853. * Avn/nmie, i. 755.
3 JouvjKil of Anal, and Plii/s., iii., ]8G9, 97. * Allen's Iluman Anatomy, pp. 259. 260.