596 CONTRIBUTIONS TO ZOOLOGICAL ANATOMY. 
According to Gerdy*, it consists of four sets of fibres, — a trans- 
verse set, a vertical set, two deep sets, and a superficial lingual 
layer. The transverse lingual muscles are placed beneath the 
superficial layers ; they traverse all the breadth of the tongue, and, 
passing between the lateral fibres of the superficial lingualis, which 
they cross almost at right angles, attach themselves to the investing 
membrane under the edge of the organ. They are divided along 
the centre of the tongue by the fibro-cellular band, the linea albe- 
scens or worm of the tongue, and behind they become gradually 
more and more curved towards the base of the organ. The ver- 
tical set stretch from the inner surface of the membrane that covers 
the superior surface of the tongue to that which invests it below, 
over its entire extent, and mixes itself freely with the fibres of the 
transverse set, in the form of a warp. They become much curved 
and oblique towards the base of the organ. The deep set of fibres 
consist of two fasciculi placed on either side under the two poste- 
rior thirds of the tongue, between the hyo-glossi and genio-hyo- 
glossi muscles. In the ox their fibres are attached behind to the 
glosso-epiglottic yellow elastic tissue. 
The superficial set of fibres are the most important of the whole, 
and alone act on the surface of the tongue and its papillae. 
This muscle consists of two distinct lamellae of fibres, extending 
from the base to the tip of the organ, and separated from each 
other by the linea albescens. In their general outline and con- 
figuration they are slightly parabolic; their concavities looking 
towards each other along the median raphe, and their convexities 
to the margins of the tongue. Posteriorly they arise by means of 
the glosso-epiglottic elastic tissue from the upper surface of the 
os hyoides, and from thence proceed forwards to the different 
portions of the adherent surface of the investing membrane. The 
inner set of fibres are considerably the shortest ; but they gradually 
become more lengthened as they are examined near the margins. 
Their free or inserted extremities are into the whole of the lower 
surface of the investing membrane. This can be proved by two 
facts, — first, by the roughened appearance of the dissection after 
its most careful removal, this condition evidently depending on 
the severing of the muscular fibres from it in their transverse 
direction ; and, secondly, from our inability to trace, even by the 
aid of a glass, any of the muscular fibres forming this layer curv- 
ing downwards to the base of the organ — the general tendency of 
all the muscles of the tongue, the intrinsic and extrinsic, being 
towards its upper surface and tip. 
* Recherches, Discussions, et Propositions d’Anatomie, de Physiologie, 
de Pathologie, &c. p. 20, et seq. Paris, 1823. 
