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DIGASTRICUS. 29
becomes a little broader, makes a turn upwards, inwards, and
forwards, and gives origin to the anterior belly, which passes on
in the same direction, to the lower part of the Chin, where it is
inserted tendinous and fleshy, into a slight depression on the
under, and a little on the posterior part of the Lower-Jaw,
almost contiguous to its fellow. (/) Besides the attachment of the
middle tendon to the Os Hyoides, there is a ligamentous binding,
This is more
which serves, in some measure, as a pulley, (g)
marked in some subjects than in others ; and this depends on
the strength of the tendinous expansion, which binds the tendon
of the Digastricus to the Os Hyoides.
When we say that these parts are attached to the Os Hyoides,
we do not mean that they can be traced quite into it, like some
other tendons in the body ; but the Os Hyoides seems to be the
most fixt point of attachment. Very often we find two anterior
bellies to each Muscle ; the uncommon one, which is the smallest,
does not pass to the Chin, but joins with a similar portion of
the other side, in a middle tendon, which is often fixed to the
Os Hyoides. At other times, we find such a portion on one
side only ; in which case it is commonly fixed to the middle
tendon of the Mylo-Hyoidaeus.
The use of these Muscles with regard to the Lower-Jaw, is

(/) [The surface for insertion of the digastric varies in position in
Mammalia. In Carnivora it is attached for a varying distance to the
inferior border of the horizontal ramus. In the Cat it is inserted,
according to Cuvier, into the angle of the jaw. Straus-Durckheim,
however, describes it as reaching the anterior half of the lower border.
In the Rodents it is prolonged to the back part of the arch of the chin,
into which it is fixed ; in the Elephant it is attached to the posterior
border of the maxilla ; in the Horse the principal portion of the muscle
is inserted into the angle ; in the Ruminants it extends as far as the
mid-length of the ramus.] (1)
{g) [The existence of an apparatus analogous to the pulley was denied
by Monro primus {vide infra, note h). Many writers describe the
tendon of the digastricus as passing through' an aponeurotic sheath
lined by a synovial membrane. Such a structure, although in some
instances apparent enough, is by no means constant.
(1) Cuvier ; Straus-Durckheim, op. cit.