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125

The maxillary muscles

The maxillary muscles

126

The m. temporalis of the Elephant is of a very complicated
structure. It arises in a great measure fleshy from the bone; but
besides this numerous tendinous leaves, which also arise from
the temporal fossa, extend into the muscle and from these a large
part of the muscular fascicles take their origin; of these tendinous
leaves those which arise the farthest downwards from the fossa
are the stronger. Also from the tendinous sheet investing the
upper and posterior part of the muscle, and from tendinous leaves,
which from it extend into the muscle, numerous muscular bundles
take their origin. — Similar to the origin is also the insertion of
the muscle: a — smaller — part of the muscular bundles insert
themselves fleshy on the mandible, but most of them on strong
tendinous leaves, which are implanted on the mandible and extend
into the muscle or — anteriorly — spread over it. The fissures
, which (in PI. 3) are seen in the surface of the muscle, are
related to the tendinous leaves in it: from both sides of the fissure
muscular fascicles extend to a tendinous leaf which reaches the
bottom of the fissure.

The musculus digastricus is a long1, slender, rather sequi-
lateral muscle, which arises from the skull close laterally to and
a little in front of the occipital condyle. Some of its fibres are
very short and insert on the posterior processus of the stylohyal,
others take their origin from the same. The muscle inserts into
the rounded angle of the mandible. It is for the greater part
fleshy, but has a rather complicated structure: it is interwoven
with tendinous slips etc. The usual tendinous intersection is
apparently wanting, the muscle being fleshy in its whole length;
but a possible remnant of the tendinous intersection we have found
in the form of an oblique tendinous stripe in the interior of the
muscle, very nearly in the middle of its length, to and from
which a part of the fleshy bundles are extending; this tendinous
stripe is on both sides covered by a fleshy sheat, belonging to
that part of the muscle, which arises from the stylohyoid. We
think that this part of our digastricus is really the m. stylo-
hyoideus, which has fused with the digastricus2; the two fleshy
sheats, between which the tendinous stripe is concealed, are the
two branches between which in man etc. the digastricus passes.
The upper bundles of our digastricus which insert into the stylohyoid
may represent the m. jugulohyoideus of the veterinarians8.

The m. pterygoideus interims (PI. 39 figs. 1—2) has a
shape similar to that of the masseter externus and a position on
the inner side of the mandible somewhat similar to that of the
masseter externus on the outer side. But the pterygoideus is much
smaller, being of hardly half the breadth and length of the masseter
externus. The muscle is for the greater part fleshy. It arises
from the pterygoid process of the alisphenoid; on the medial side
there is a little tendinous plate at its origin. Its insertion is on
the inner side of the ramus of the mandible near the posterior
margin of the bone. The insertion is closely adjacent to the
insertion of the hindmost (upper) half of the masseter externus,
so much so that the two muscles apparently fuse at their posterior
end. The direction of the fibres is essentially from before
backwards and somewhat from within outwards.

The m. pterygoideus externus is a short, thick, fleshy
muscle, which arises from the upper part of the pterygoid process
of the alisphenoid and inserts on the medial side of the
ramus of the mandible between the condyle and the large inferior
dental foramen. The direction of the fascicles is almost
horizontal, from before backwards and from within outwards.

Of the above mentioned masticatory muscles the temporalis
is evidently the principal bearer and lifter of the huge and heavy
mandible; this work is so to say totally accomplished by that
muscle alone. To a slight extent it receives help in this function
from the masseter profundus and the anterior part of the masseter
superficialis. For the rest the masseter superficialis and the two
pterygoidei move the mandible from behind forwards; if working
only on one side the pterygoidei can also effect a movement

1 In Plate 2 only the upper end of the muscle is visible; the rest, almost two
thirds of the whole length, are concealed on the inner side of the mandible.

2 Cf. Miall & Greenwood, Anat. of the Indian Elephant in: Journ. of Anat. a. Phys.
Vol. 12, p. 391.

3 See for instance Ellenberger & Baum, Vergl. Anat. d. Haustiere, 14. Aufl., p. 379.

obliquely, from without inwards. The digastricus pulls the mandible
backwards.

B. FRAGMENTARY DESCRIPTION OF THE MUSCLES
ON THE CRANIAL PART OF THE NECK

The muscles of the neck we have only had an opportunity
to study in the young Elephant which we first received, and the
piece at our disposal for dissection was only the head and the
greater, cranial, part of the neck, whilst the chest and herewith
the origins of several muscles could not be examined any more.
A complete description of the muscles of the neck is therefore
not possible. On the other side we have not been able to look
totally away from them, because some of them are significant as
to the forming of the skull and the shape of the head. In the
following statements we particularly emphasize those points, that
are of interest in this respect.

Musculus splenius. As the posterior part of the muscle is
not present in the specimen we can only describe the cranial part
and the insertion. It is quite an enormous muscle, which is posteriorly
appended to the skull as a hood. It is composed of two
layers, a superficial and a deeper; the latter is only above covered
by the superficial layer, while laterally it stands freely out. The two
layers are totally separated and are really two independent muscles.

The superficial layer, m. splenius superficialis, has a fleshy
insertion, partly at the top of the occipital plane, partly in a tendinous
raphe dorsally in the median line of the neck. A little
behind the insertion the muscle presents a mighty swelling standing
out as a cushion; before and behind this place it is more
flattened. This muscular cushion, which is through a median
furrow separated from the corresponding cushion of the other
side, plays a singular part in the exterior of the Indian Elephant.
The fact is that in the live Elephant this pair of muscular cushions
make the impression as if they are a part of the skull,
although they are really situated quite behind the skull, and they
form that part of the „head", which rises the furthest dorsally;
they appear as a pair of rounded eminences. When the animal
lifts its head, these eminences become distinctly higher, more
pointed: the muscles contract and become thickened. — The anterior
part of the muscle unto the hind end of the cushion is
entirely fleshy and the muscular fascicles of it have a longitudinal
direction. But directly behind the cushion is seen the anterior
end of a strong tendinous band — evidently the tendon, through
which the muscle arises from the ligamentum nuchas1 —, to the
anterior end, lateral margin and inferior side of which the said
longitudinal fascicles attach themselves. Along the medial margin
of the said tendon numerous fleshy fascicles are attached, which
have posteriorly a transverse direction and gradually towards the
cushion become more and more oblique and at last extend alongside
the longitudinal fascicles of the cushion.

The deeper layer of the splenius, the m. splenius profundus,
is a mighty muscle, which posteriorly is of considerable thickness
, while anteriorly it becomes very thin. The fleshy fibres arise
from the median raphe mentioned above — from which also fibres
of the ligamentum nuchse take their origin —, make their way
obliquely forwards and somewhat outwards and insert themselves,
partly with numerous short tendinous slips, partly fleshy, on the
occipital plane below the splenius superficialis and far outwards
nearly unto the auricular orifice. On its inferior side it is partly
covered with a thick elastic blade, which is connected with the nuchal
ligament.

A similar form as the m. splen. profundus has the muse,
complexus, which is covered by it. The complexus is thickest
in its medial part, which is intimately connected with that of the
opposite side and here also is woven together with the dorsal
dispersed fibres of the nuchal ligament. The strong muscle inserts
fleshy and with thin tendinous leaves on a considerable part
of the occipital plane; the furthest upwards it reaches in its median
part. Laterally it does not reach nearly so far as splenius.

Of the short muscles on the cranial end of the neck the iiiu-
sculi recti postici major and minor are of particular interest
because of their uncommonly strong development. The m. r. p.

1 Miall & Greenwood, Anat. of the Ind. Eleph. in: Journ. Anat. Phys. Vol. 12,
1878, p. 396.